查看更多>>摘要：A practical and efficient total synthetic route of the resveratrol dimer (+/-)-e-viniferin (2) with benzyl as protecting group for phenols was achieved with high overall yield. The synthetic approach involved a palladium-catalyzed direct arylation, triethylsilane-mediated reduction of benzofuran, and selective debenzylation reaction. Selective debenzylation in the presence of reducible and acid-sensitive groups catalyzed using Pd/C and 1,4-cyclohexadiene was implemented to complete the total synthesis. (c) 2022 Elsevier Ltd.
查看更多>>摘要：Boc-protected (3R,4S)-3,4-dihydroxypiperidine diol 1 is an enantiomerically pure, highly valuable synthetic intermediate. Herein we report the development of two scalable synthetic strategies avoiding the use of hazardous sodium azide, as well as the formation of azido intermediates. Starting from the readily available 2-deoxy-D-ribose, it was possible to produce a substantial amount of diol 1 following two distinct routes, without a significant decrease in performance when scaling up from 1- to 230-mmol. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A diaminomethylenemalononitrile organocatalyst efficiently promoted the asymmetric conjugate addition-cyclization of cyclohexane-1,2-dione with benzylidenemalononitriles, resulting in the corresponding 2-amino-8-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles in high yields with excellent enantioselectivities (up to 90% ee). Use of the novel diaminomethylenemalononitrile organocatalyst made it possible to obtain the desired products with higher enantioselectivities compared with the previous reports.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A convergent approach for the stereoselective total synthesis of zeaenol and cochliomycin A is reported. The key steps involved are alkyne generation using Ohira-Bestmann reagent onto sugar lactol, NaH mediated one-pot esterification and acetonide deprotection, Trost's protocol of hydrosilylation followed by protodesilylation to get exclusively E-olefin from internal alkyne and ring closing metathesis (RCM) reaction. Readily accessible D-lyxose has been utilized as the chiron substrate for generation of aliphatic chain fragment and 2,4,6-trihydroxybenzoic acid has been used for the synthesis of vinylated arene fragment. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：The evaluation of a new scaffold organocatalyst of chiral spiro (S)-1-benzylspiro[indoline-3,2'-pyrrolidin]-2-one in the enantioselective aldol condensation between isatins and acetone has been executed, and a series of chiral 3-hydroxy-3-(2-oxopropyl)-indolin-2-ones have been prepared in excellent yields (up to 97%) with good enantioselectivities (up to 82% ee). Compared with the generally used chiral prolinamide organocatalysts, the enantioselectivities of our catalysts are more possibly determined by steric control rather than amide NAH hydrogen bonding which is generally beneficial for an enamine organocatalysis. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Evoninic acid (3) is a component of a 14-membered bislactone of bioactive dihydro-b-agarofuran sesquiterpenoids. The unique structure of 3 is characterized by C2',C3'-disubstituted pyridine and vicinal C7'S,C8'S-dimethyl groups. Here we report a new synthetic route to enantiopure 3. A chiral oxazolidinone controlled the stereochemical outcome of olefin hydrogenation, establishing the absolute configuration of the C7'S-methyl group. The C7'S-stereocenter then influenced the diastereoselectivity to install the C8'S-methyl group.
查看更多>>摘要：Using conveniently available Cu(CH3CN)4PF6 and PxNy-type ligands as starting material, copper(I) complexes 1 and 2 could be easily prepared. Furtherly, we confirmed the structures of these novel copper (I) complexes by studying X-ray diffraction of the single crystals. The hydrosilylation of a wide range of ketones catalyzed by the well-designed copper(I) complex proceeded smoothly under mild reaction conditions, obtaining the corresponding alcohols with high yields. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A four step synthetic process has been developed for the synthesis of orally active ribonucleoside molnupiravir (MK-4482 & EIDDD-2801), starting from a readily available D-ribose. The synthesis involves the formation of acetonide from secondary hydroxy groups of the ribose, isobutrylation of primary and anomeric hydroxy groups, ribosylation of cytosine and one-pot hydroxyamination of cytosine ring along with the hydrolysis of acetonide. It is an effective process that can replace the high cost starting materials like uridine or cytidine that are being used in previous synthetic routes for MK-4482. The use of low cost starting materials with less number of synthetic steps is expected to expand access to molnupiravir. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We report here the use of azidotrimethylsilane/ Selectfluor via single electron transfer radical reaction for the highly selective introduction of azido group into a wide range of prenylated molecules. Upon condition optimization, the fluorescent labeling of nucleic acids with prenyl modification in vitro have been achieved following this well-established protocol along with subsequent click reaction with DBCO-Cy5.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Desymmetrization strategies have unlocked numerous possibilities in complex target-driven synthesis by enabling the construction of diverse three-dimensional molecular architectures. While methods of achieving enantiotopic group discrimination have found a central role in asymmetric synthesis by providing access to enantiopure intermediates, diastereotopic group discrimination (or "local desymmetrization") has evolved in parallel as a means of elaborating upon existing stereochemical features through substrate control. In this Digest, selected synthetic efforts from the last five years are examined through the lens of local desymmetrization, framing each advance on the basis of stereochemical generalities. (c) 2022 Elsevier Ltd. All rights reserved.
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