Tetrahedron Letters

Editorial Board ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5
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Advances in chemoselective and/or stereoselective semihydrogenation of alkynes ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): K.C. Kumara Swamy, Alla Siva Reddy, K. Sandeep, A. Kalyani The chemoselective semihydrogenation of alkynes is one of the most important reactions in synthetic organic chemistry. During the last decade or so, a multitude of innovative catalytic methods have been developed to address the selective hydrogenation of alkynes. This digest focuses on the recent developments in chemoselective semihydrogenation of alkynes to alkenes. Graphical abstract image
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Recent advance in transition-metal-catalyzed oxidant-free 4+1 annulation through C–H bond activation ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): Chuan Zhu, Cheng-Qiang Wang, Chao Feng 4+1 annulation based reaction offers a versatile tool for the synthesis of 5-membered carbo/heterocycles. Recent advances of 4+1 annulation through transition-metal-catalyzed C–H bond activation have provided straightforward and widely applicable alternatives to the traditional methods. In particular, the redox-neutral strategies emerged in the past 5 years overcome the inherent disadvantages caused by the external oxidant which are generally required in the early protocols to regenerate the active catalyst, such as limited substrate scope, harsh reaction conditions and generation of stoichiometric by-products. Progress in oxidant-free 4+1 annulations through transition-metal-catalyzed C–H bond activation are discussed in this review until September 2017. Graphical abstract image
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Transition metal mediated selective C vs N arylation of 2-aminonaphthoquinone and its application toward the synthesis of benzocarbazoledione ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): Polu Ashok, Andivelu Ilangovan Selective C vs N-arylation of 2-aminonaphthoquinone was achieved using different transition metal salts and arylboronic acids. Mn(OAc)3·2H2O provided C-arylated product whereas NiCl2·6H2O and Cu(OAc)2·H2O provided N-mono arylated and N,N-diarylated products respectively. Usefulness of the C and N arylated product was demonstrated by converting it into benzocarbazoledione. Graphical abstract image
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Synthesis of novel 1,2-dihydropyrrolo[1,2-a]pyrazin-1(2H)-one derivatives ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): Iryna O. Yaremchuk, Lyubov V. Muzychka, Oleg B. Smolii, Olexandr V. Kucher, Svitlana V. Shishkina The iodolactonization product obtained from methyl 7-allylpyrrolo[2,3-d]pyrimidine-6-carboxylate was used for the synthesis of novel 1,2-dihydropyrrolo[1,2-a]pyrazin-1(2H)-one derivatives, containing carboxamide- and methylamine-groups on the pyrrole ring of the heterocycle. Graphical abstract image
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Urea mediated 5-substituted-1H-tetrazole via [3 + 2] cycloaddition of nitriles and sodium azide ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): B. Yakambram, A. Jaya Shree, L. Srinivasula Reddy, T. Satyanarayana, P. Naveen, Rakeshwar Bandichhor A simple, new and convenient metal free procedure for the synthesis of 5-substituted 1H-tetrazoles using various nitriles and sodium azide in the presence of urea and acetic acid with good to high yields is developed. The reaction plausibly proceeds through in situ formation of urea azide active complex without toxic and/or expensive metal catalysts. Graphical abstract image
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Visible-light-activated selective synthesis of sulfoxides via thiol-ene/oxidation reaction cascade ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): Manjula Singh, Arvind K. Yadav, Lal Dhar S. Yadav, R.K.P. Singh A convenient, highly selective and metal-free synthesis of sulfoxides from alkenes and thiols using NHPI as an inexpensive and reusable organophotoredox catalyst is reported. The protocol involves radical thiol-ene/oxidation reaction cascade and utilizes visible light and air (O2) as inexpensive, readily available, non-toxic and eco-sustainable reagents to afford up to 96% yields of the product at room temperature. Graphical abstract image
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Studies towards the total synthesis of Phostriecin ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): Gavireddy Chaithanya Kumar, Katta Muralikrishna, Vavilapalli Satyanarayana, Chintakrinda Suresh Kumar, Jhillu Singh Yadav A synthetic approach toward the phostriecin, an antitumor natural product is described. The key features of the present synthesis are Wittig reaction, synthesis of homoallylic alcohol using Brown’s protocol (alkoxyallylboration) and RCM for the creation of unsaturated lactone moiety of phostriecin. Graphical abstract image
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Mannich Reaction of Indole with Cyclic Imines in Water ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): Liang-Hui Xie, Jie Cheng, Zi-Wei Luo, Gui Lu An efficient MsOH promoted direct Mannich reaction of indoles with α-nonsubstituted aliphatic cyclic imines has been developed. The reactions were performed in water and the obtained piperidin-2-yl-indoles act as a useful precursor for the synthesis of various alkaloid-like derivatives. Graphical abstract image
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Theoretical study on the reaction mechanism of Pd(OAc)2-catalyzed trifluoroethylation: Role of additive CF3COOH ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): Dimao Wen, Binfang Yuan, Rongxing He, Wei Shen, Ming Li The mechanism of Pd(OAc)2-catalyzed trifluoroethylation of aromatic systems is explored using the density function theory (DFT) computations. The calculation results indicate that the whole catalytic cycle involves a coordinated process of catalyst Pd(OAc)2 with acetanilide 1a, a C–H bond activation and a two-step migration of CF3CH2– group. The interesting role of additive (CF3COOH) is that it can react with substrate 2a (mesityl(trifluoroethyl)iodonium triflate) to form an active species mesityl(trifluoroethyl)iodonium trifluoroacetate 2a′. 2a′ can assist the C–H activation to decrease the rate-limiting free energy barrier of the catalytic reaction by changing the rate-limiting step from the transferring process of CF3CH2– group to the C–H bond activation. Graphical abstract image
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A new method of using supercritical carbon dioxide as a green solvent for synthesis and purification of 5,5‴-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2‴-quaterthiophene, which is one of n-type organic semiconducting materials ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5 Author(s): Ryuji Hirase, Koji Honda, Mari Ishihara, Hideki Yoshioka, Hirosato Monobe We have investigated synthesis as well as purification of 5,5‴-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2‴-quaterthiophene (BFH-4 T, n-type organic semiconducting material) using supercritical carbon dioxide (scCO2) as a green solvent. BFH-4T was obtained in good selectivity and high yield by TDAE/PdCl2-catalyzed reductive coupling reaction of 5-bromo-5′-(tridecafluorohexyl)-2,2′-bithiophene in scCO2. We have also successfully established purification of the reaction mixture by passing scCO2 in the reaction vessel. The product was yellow powder of BFH-4T with purity of more than 99% and Pd catalyst was not contained. Graphical abstract image
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Graphical abstract TOC continued ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5
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Graphical abstract TOC ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5
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Graphical abstract TOC ()
Publication date: 31 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 5
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Editorial Board ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4
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Application of arylsulfonium salts as arylation reagents ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Ze-Yu Tian, Yu-Tian Hu, Han-Bing Teng, Cheng-Pan Zhang Arylsulfonium salts are versatile arylation reagents for the synthesis of functional molecules. This digest focuses on the recent advances on the transition metal-mediated or -free arylation using the stable arylsulfonium salts or the metastable arylsulfonium intermediates as arylation agents. Graphical abstract image
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Chiral metal cluster and nanocluster complexes and their application in asymmetric catalysis ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Qiong-You Zhang, Liang Zhao Asymmetric catalysis has always been the focus of attention for synthetic chemistry. In this review, we summarize recent advances in the synthesis and asymmetric catalysis application of chiral metal clusters, nanoclusters and nanoparticles. Graphical abstract image
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Recent advances in mechanochemical C–H functionalization reactions ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Shujuan Zhao, Yipeng Li, Chao Liu, Yanchuan Zhao The mechanochemical synthesis has provided a greener alternative to solution-based approaches by eliminating the use of organic solvents and reducing the energy consumption. The C–H functionalization is among the most concise and economical synthetic strategies. The combination of the benefits from these two methods provides new opportunities to further increase the efficiency and sustainability of organic synthesis. In this digest, we aim to provide a brief overview of the recent advances in mechanochemical C–H functionalization reactions. Graphical abstract image
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Recent developments in peptide macrocyclization ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Jie Wu, Jian Tang, Hongfei Chen, Yadong He, Huan Wang, Hequan Yao Cyclic peptides have been widely applied in fields ranging from drug discovery to nanomaterials. After years of development, the preparation of peptide macrocycles, especially late-stage macrocyclization of peptides, remains challenging using traditional synthetic methods. This digest highlights recent developments in the synthesis of cyclic peptides. Graphical abstract image
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Functional nanomachines: Recent advances in synthetic molecular machinery ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): James A. Findlay, James D. Crowley A mini-review: As the top-down approach for miniaturisation of technology reaches its inherent limitations, robust strategies to build nanoscale machinery components, which have the ability to convert an input energy into motion, from the molecular level up, become increasingly important. Nature is certainly the most proficient in the control of molecular level motion; nevertheless, many successes have been enjoyed in the pursuit of mimicking key aspects of nature’s molecular machines, including two state switches, ion pumps, unidirectional rotary motors and molecular robots that can move molecular cargo. This mini-review outlines of some of the most impressive recent examples towards this end. Graphical abstract image
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Recent advances on catalytic asymmetric difunctionalization of 1,3-dienes ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Yang Xiong, Youwen Sun, Guozhu Zhang 1,3-Dienes and derivatives are either feedstock chemicals or easily available materials. Catalytic difunctionalization of 1,3-diene is one of the most powerful methods for carboncarbon bond formation with rapid increase of the molecular complexity and synthetic value in an atom economic way. By choosing proper metals and chiral ligands, a variety of catalytic asymmetric difunctionalization of conjugated dienes in a highly regioselective fashion have been reported. In this digest review, we will summarize recent advances on this topic based on different metals. We will also introduce unique phenomena that include reversal of regio- and diastereoselectivity. Graphical abstract image
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A novel highly selective ratiometric fluorescent sensor for relay recognition of Zn2+ and H2PO4− ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Kui Du, Shizhen Niu, Xinzhi Chen, Pengfei Zhang A novel fluorescent sensor (AQTF1) based on the N-(quinolin-8-yl) tetrahydrofuran-2-carboxamide was designed and synthesized. This new sensor demonstrated high selectivity for the Zn2+ without the interference from Cd2+. The detection limit of this probe was calculated to be 10.8nM for Zn2+. The in situ prepared AQTF1-Zn2+ complex was used for detection of H2PO4 − and displayed good selectivity from the common anions. Furthermore, the AQTF1 displayed good ratiometric response for the relay recognition for Zn2+ and H2PO4 −. Graphical abstract image
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Silver-catalyzed [3+2+1] annulation of aryl amidines with benzyl isocyanide ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Xiaodong Lu, Xiaoyi Xin, Boshun Wan A silver-catalyzed [3+2+1] annulation of amidines with benzyl isocyanide toward 2,4-diaryl-1,3,5-triazines was developed. A variety of symmetrical and unsymmetrical products were obtained in moderate to good yields. This work also features an oxidant-free approach to 2,4-disubstituted triazines. Graphical abstract image
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Chemoselective oxidation and deprotection of para-methoxybenzylic position with (diacetoxyiodo)benzene in acetic-trifluoroacetic acid ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Chun-Yu Lin, Ping-Shin Yang, Pang-Yu Chou, Chi Wi Ong (Diacetoxyiodo)benzene in the presence of acetic–trifluoroacetic acid in THF has been developed for the chemoselective para-methoxybenzylic CH bond oxidation to provide aryl carbonyl compounds at room temperature. The reaction condition is also applicable for the chemoselective deprotection of para-methoxybenzyl (PMB) ether in the presence of benzyl ether. Graphical abstract image
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Metal-free one-pot α-benzoxylation of benzylic alcohols with acids or aldehydes ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Yefu Zhu, Yong Zheng, Weibin Song, Bole Wei, Lijiang Xuan A metal-free strategy has been developed for α-benzoxylation of benzylic alcohols with acids or aldehydes. The reaction proceeds via sequential oxidation and α-benzoxylation in one pot. Importantly, the reactions are performed in metal-free condition and utilize cheap aqueous TBHP as an oxidant, affording α-benzoxy ketones in moderate to good yields. Graphical abstract image
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Efficient synthesis of chalcone-4′-sulfonyl chlorides and fluorides ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Dmitrii Semenok, Alexey Kletskov, Evgenij Dikusar, Vladimir Potkin, Oleg Lukin A library of 4′-chloro- and 4′-fluorosulfonyl-substituted chalcones was prepared via the aldol-type condensation reactions of 4-acetylbenzene-1-sulfonyl halides with various aromatic aldehydes, either in absolute ethanol or glacial acetic acid, in the presence of dry HCl. This represents the first examples of chalcone sulfonyl halides in which the phenone ring bears one of these functional groups. The reactivity of the chalcone sulfonyl halides were strongly dependent on the styrene ring substituents; sulfonyl chlorides reacted with most nucleophiles (e.g. amines, alcohols), while sulfonyl fluorides reacted only with charged nucleophiles (e.g. phenolates). Graphical abstract image
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Cyclopiane-type diterpenes from the deep-sea-derived fungus Penicillium commune MCCC 3A00940 ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Siwen Niu, Zuowang Fan, Xixiang Tang, Qingmei Liu, Zongze Shao, Guangming Liu, Xian-Wen Yang Three new cyclopiane diterpenes (1–3) and one rare spirocyclolide (5) were isolated from the deep-sea-derived fungus Penicillium commune MCCC 3A00940, along with 11 known compounds. The planar structures of the new compounds were determined by extensive analysis of their NMR and HRESIMS spectra, and the absolute configurations were established on the basis of specific rotation data in association with calculated ECD spectra. Four of the cyclopiane diterpenes (1–4), with a rigid 6/5/5/5 fused tetracyclic ring framework, are rarely found in Nature. Notably, conidiogenone J (1) is the first naturally occurring enantiomer of the cyclopiane diterpenes. Additionally, penijanthine B (6) and 3-hydroxy-5-methoxystilbene (14) exhibited moderate antiallergic effects with IC50 values of 30 and 33 μM, respectively. Graphical abstract image
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S,O-ligand-promoted palladium-catalyzed C–H olefination of arenes with allylic substrates ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Kananat Naksomboon, Yolanda Álvarez-Casao, Michiel Uiterweerd, Nick Westerveld, Beatriz Maciá, M. Ángeles Fernández-Ibáñez An efficient catalytic system for the C – H olefination of arenes with different allylic substrates is reported. The catalytic system is based on Pd(OAc)2 and a readily accessible bidentate S,O-ligand. The methodology shows high activity with a wide range of arenes, including bulky and, electron-rich and -poor arenes. The applicability of this catalyst is demonstrated in the late-stage functionalization of the complex molecule O-methylestrone. Graphical abstract image
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Laccase-catalyzed, aerobic oxidative coupling of 4-substituted urazoles with sodium arylsulfinates: Green and mild procedure for the synthesis of arylsulfonyl triazolidinediones ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Abdollah Rahimi, Davood Habibi, Amin Rostami, Mohammad Ali Zolfigol, Shadpour Mallakpour The direct aerobic oxidation of 4-substituted urazoles using the laccase enzyme from Trametes versicolor in a phosphate buffer solution at ambient temperature, and subsequent cross-coupling with sodium benzenesulfinates was investigated to afford arylsulfonyl-1,2,4-triazolidine-3,5-dione derivatives in good to high yields. Graphical abstract image
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Excited-state intramolecular proton transfer (ESIPT) fluorescence from 3-amidophthalimides displaying RGBY emission in the solid state ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Hideki Okamoto, Kazumasa Itani, Minoru Yamaji, Hiroyuki Konishi, Hiromi Ota Fluorescence properties of phthalimide derivatives (1) incorporating sulfonamide and acetamide functionalities at the 3-position were investigated both in solution and in the solid states to reveal the effects of the amide functionalities on the fluorescence properties. In the solid state, sulfonamides 1a and 1b, respectively, gave off red (λF max 595 nm) and green (λF max 537 nm) emission through an ESIPT process. Acetamides 1c and 1d, respectively displayed blue (λF max 432 nm) and yellow (λF max 560 nm) emission. Through simply modifying the amide functionality, phthalimide 1 displayed multicolor RGBY emission in the solid state. Graphical abstract image
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Base-catalyzed reactions enhanced by solid acids: Amine-catalyzed nitroaldol (Henry) reactions enhanced by silica gel or mesoporous silica SBA-15 ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Kiyoshi Tanemura, Tsuneo Suzuki The reactions of various aldehydes with CH3NO2 catalyzed by Et3N, n-C6H13NH2, and Me2N(CH2)2NH2 were accelerated by the addition of silica gel to give aromatic (aliphatic) β-nitroalcohols, aromatic nitroalkenes, and aromatic 1,3-dinitroalkanes, respectively. Mesoporous silica SBA-15 showed higher activity than silica gel for the synthesis of aromatic nitroalkenes by the reactions of the corresponding aldehydes with CH3NO2 catalyzed by n-C6H13NH2. Graphical abstract image
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A recyclable/reusable hydrotalcite supported copper nano catalyst for 1,4-disubstituted-1,2,3-triazole synthesis via click chemistry approach ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Mitali Chetia, Praveen Singh Gehlot, Arvind Kumar, Diganta Sarma Using hydrotalcite as solid support, copper nano particles were synthesized and used in azide-alkyne cycloaddition reaction en route to the synthesis of 1,4-disubstituted-1,2,3-triazoles. The catalyst is heterogeneous and can be recycled and reused easily. Room temperature reaction condition and the use of ethylene glycol as solvent make it an environment friendly system. Graphical abstract image
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Steric redirection of alkylation in 1H-pyrazole-3-carboxylate esters ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Stephen W. Wright, Eric P. Arnold, Xiaojing Yang The alkylation of ethyl 1H-pyrazole-3-carboxylate with a variety of alkylating agents in the presence of K2CO3 was found to largely favor the formation of ethyl 1-substituted pyrazole-3-carboxylates. The alkylation could be sterically redirected by the use of a triphenylsilyl group (ethyl 3-(triphenylsilyl)-1H-pyrazole-5-carboxylate) to provide synthetically useful yields of ethyl 1-substituted-3-(triphenylsilyl)-1H-pyrazole-5-carboxylates. The triphenylsilyl group could be removed with Bu4NF. Other triorganosilyl groups (TMS, TES, TBDMS) failed to provide significant redirection, while TIPS proved refractory to protodesilylation. Graphical abstract image
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Halohydrin dehalogenase-catalysed transformations of epifluorohydrin ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Maja Majerić Elenkov, Mirjana Čičak, Ana Smolko, Anamarija Knežević Biocatalytic ring-opening of epifluorohydrin has been performed by using halohydrin dehalogenase. The enzyme from Mycobacterium sp. GP1 (HheB2) catalysed reaction with high regioselectivity and low enantioselectivity in the presence of different nucleophiles, producing racemic 1-substituted 3-fluoro-2-propanols. No by-products resulting from the ring-closure reaction have been detected, confirming that vicinal fluoro alcohols are not substrates for HHDH. Four different 3-fluoro-2-propanols were prepared under mild reaction conditions starting from epifluorohydrin. High conversions of 85–100% were reached within 1–3 h and depending on the nucleophile used products were isolated in 31–92% yields. Graphical abstract image
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Isolation and structure determination of a new thiopeptide globimycin from Streptomyces globisporus subsp. globisporus based on genome mining ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Issara Kaweewan, Hisayuki Komaki, Hikaru Hemmi, Shinya Kodani Based on genome-mining, a new thiopeptide globimycin was discovered from the extract of Streptomyces globisporus subsp. globisporus, along with known one radamycin. The structure of globimycin was established by a combination of 2D NMR and ESI-MS experiments, and globimycin was identified to be a structural isomer of a known thiopeptide methylsulfomycin. The proposed biosynthetic gene cluster for globimycin and radamycin was found in the genome of S. globisporus subsp. globisporus. Graphical abstract image
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Convenient preparation of pinometostat and related 5′-deoxy-5′-amino adenosine derivatives as well as their activity against DOT1L ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Tongchao Liu, Huanming Ren, Cong Li, Guohua Chen, Maosheng Cheng, Dongmei Zhao, Jingkang Shen, Jia Li, Yubo Zhou, Bing Xiong, Yue-Lei Chen From adenosine and 2′-C-Me adenosine, a 3-step route towards nucleoside DOT1L inhibitors, including pinometostat, EPZ5677, and FED1, was established. With useful structural-activity relationship information, the newly prepared 2′-C-Me adenosine derivatives contribute to the limited repertoire of ribose-modified nucleoside DOT1L inhibitors. In general, this new synthetic method will facilitate not only the study of nucleoside DOT1L inhibitors, but also the synthetic and medicinal chemistry research of 5′-deoxy-5′-amino adenosine derivatives. Graphical abstract image
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Corrigendum to “Macahydantoins A and B, two new thiohydantoin derivatives from Maca (Lepidium meyenii): Structural elucidation and concise synthesis of macahydantoin A” [Tetrahedron Lett., 58 (17) (2017) 1684–1686] ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4 Author(s): Mu-Yuan Yu, Xu-Jie Qin, Li-Dong Shao, Xing-Rong Peng, Lei Li, Han Yang, Ming-Hua Qiu
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Graphical abstract TOC continued ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4
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Graphical abstract TOC ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4
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Graphical abstract TOC ()
Publication date: 24 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 4
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Editorial Board ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3
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Recent advances in the synthesis of N-alkenyl carbazoles ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3 Author(s): Yasushi Obora N-Alkenyl carbazoles are important building blocks of poly(vinylcarbazole), which is used in photosensitive materials, semiconductors, electroluminescent devices, and non-linear optical materials. Recently, a CN bond formation reaction using transition-metal-catalyzed amination and transition-metal-catalyzed vinylation was successfully extended to the synthesis of N-alkenyl carbazoles. In this paper, I discuss recent examples of the synthesis of N-alkenyl carbazoles, including palladium and copper-catalyzed cross-coupling reactions of carbazoles with alkenes/alkenyl halides, and iridium-catalyzed vinylation of carbazole using vinyl acetate. Graphical abstract image
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Visible-light-induced halogenation of aliphatic CH bonds ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3 Author(s): Haiyong Tu, Shengqing Zhu, Feng-Ling Qing, Lingling Chu Alkyl halides are of particular interests in the areas of pharmaceutical, agrochemical, and material sciences. Direct CH halogenation has been recognized as the most efficient method for the introduction of halogen atoms into organic molecules. This Digest paper highlighted some of the most recent and significant developments in the visible light-promoted halogenation of aliphatic CH bonds. Graphical abstract image
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Recent advance in radical fluoroalkylation with sulfinate salts ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3 Author(s): Yong Zhao, Feng Liu In the last few years, the incorporation of a fluoroalkyl moiety into an organic molecule has been extensively studied. Especially, radical fluoroalkylation, involving the formation of CC and Cheteroatom bonds, presents its valuable synthetic potential to achieve fluoroalkylated compounds. This digest paper highlights recent progress on fluoroalkylation with sulfinate salts, and focuses on radical tri-/di-/monofluoromethylation during the last five years. Graphical abstract image
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Recent topics in application of selective Rh(II)-catalyzed CH functionalization toward natural product synthesis ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3 Author(s): Takayuki Yakura, Hisanori Nambu Direct CH bond functionalization reactions promise to be among the most efficient methods for the synthesis of organic molecules. This review focuses on recent syntheses of natural products via chemo-, regio-, and stereoselective Rh-catalyzed CH insertion reactions. Graphical abstract image
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Amino- and azidotrifluoromethylation of alkenes ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3 Author(s): Yu Tian, Su Chen, Qiang-Shuai Gu, Jin-Shun Lin, Xin-Yuan Liu Trifluoromethylation of alkenes has long been the interest of synthetic chemists. It is not only because of the great importance of F-containing compounds, but also on account of the pleasure of cracking the challenges in methodology development in this field. In particular, amino- and azidotrifluoromethylation of alkenes have recently been developing in a fast speed. This digest mainly deals with this advancement in racemic copper- and photocatalyzed amino- and azidotrifluoromethylation of alkenes while giving special highlight on our recent breakthrough on the copper-catalyzed asymmetric aminotrifluoromethylation reaction. Graphical abstract image
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Recent topics in dual hydrogen bonding catalysis ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3 Author(s): Yasuhiro Nishikawa Dual hydrogen bonding donors have received much attention in the area of organocatalysis after the discovery of chiral thiourea derivatives that act as asymmetric catalysts. This digest focuses on recent advances in this area categorized in the following three topics: 1) enhanced hydrogen bonding donor catalysis; new scaffolds with improved reactivity and selectivity are introduced and compared with established catalysts; 2) anion binding catalysis; recent advances in terms of catalysts and their applications is addressed; 3) multiple catalysis involving dual hydrogen bonding catalysts; a relatively new field of dual hydrogen bonding donor catalysis combined with other catalysis is introduced. Graphical abstract image
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Recent topics in total syntheses of natural dimeric naphthoquinone derivatives ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3 Author(s): Shogo Kamo, Kouji Kuramochi, Kazunori Tsubaki This digest overviews successful synthetic approaches to natural dimeric 1,4-naphthoquinones. Several natural dimeric 1,4-naphthoquinone derivatives have been isolated from natural sources including plants, bacteria, and fungi. They have diverse structures and attractive biological activities. However, it is difficult to construct the dimeric scaffolds efficiently and selectively, because 1,4-naphthoquinones and their derivatives are highly reactive. Efficient and attractive synthetic methodologies to construct unique dimeric 1,4-naphthoquinone skeletons are reviewed. Graphical abstract image
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Short synthesis of epi-cytoxazone via oxazoline formation through intramolecular benzylic substitution of a bis-trichloroacetimidate ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3 Author(s): Yoshitaka Matsushima, Moe Ishikawa, Rina Shibasaki, Yuki Nojima A short and efficient method for synthesizing epi-cytoxazone via the corresponding oxazoline intermediate was developed. The formation of the oxazoline ring, which proceeds through an SN1 mechanism to ensure that the trans-oxazoline stereochemistry is retained, was induced by intramolecular benzylic substitution of a 1,2-bis-trichloroacetimidate, starting from the known enantiomerically pure diol. Graphical abstract image
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Synthesis of biotinylated diazinon: Lessons learned for biotinylation of thiophosphate esters ()
Publication date: 17 January 2018 Source:Tetrahedron Letters, Volume 59, Issue 3 Author(s): Kyle G. Nottingham, Andrew McNally, Brian R. McNaughton Biotinylation permits recovery of a molecule from a complex mixture, with commercially available streptavidin containing products (such as streptavidin-coated beads). As part of a larger effort to evaluate reagents capable of degrading diazinon, a thiophosphate insecticide, we pursued biotinylation of this molecule. Our strategy focused on replacing a single thiophosphate ethyl ester with an ester linkage that contains biotin. Multiple approaches—using published methods—were unsuccessful and resulted in no reactivity, or degradation of starting material. Here, we report a successful strategy for the synthesis of biotinylated diazinon, which is likely applicable to alternative thiophosphate esters and other biotinylated molecules. Graphical abstract image
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