Bu 3 SnH介导的α-溴酰胺8的自由基环化,在N-乙烯基键的末端带有苯基和苯硫基取代基,以4 -exo-trig方式进行,得到β-内酰胺9。掺入产物9中的苯基的四氧化钌氧化提供了4-氧代-2-氮杂环丁烷乙酸13的新合成,4-氧代-2-氮杂环丁烷乙酸是(±)-PS-5的有用中间体。还通过N的不对称自由基环化获得了分别用于合成(+)-PS-5和(+)-硫霉素的关键中间体手性4-氧代-2-氮杂环丁烷乙酸23和36。-在侧链具有手性助剂的乙烯基-α-溴酰胺。
Direct α-Chalcogenation of Aliphatic Carboxylic Acid Equivalents
作者:Aniket Gupta、Ajijur Rahaman、Sukalyan Bhadra
DOI:10.1021/acs.orglett.9b02424
日期:2019.8.2
A novel approach to α-chalcogenation of aliphaticcarboxylicacids has been developed by means of transforming them as the corresponding benzazoles. The catalyst system, consisting of CuI, DMSO, and a base, operates through a unique mechanism to access a range of practically significant thio- and selenoethers that are otherwise challenging to achieve. The applicative potentials have been exemplified
通过将脂肪族羧酸转化为相应的苯唑类,开发了一种将脂肪族羧酸进行 α-硫属元素化的新方法。由 Cu I 、DMSO 和碱组成的催化剂体系通过独特的机制运行,以获取一系列具有实际意义的硫醚和硒醚,否则这些化合物难以实现。应用潜力已通过利用所得硫属化合物作为合成生物学相关分子和合成中间体的前体来举例说明。
A Facile One-Pot Synthesis of α-Hydroxy Acids and Their Derivatives
作者:Claudie Florac、Philippe Le Grel、Michèle Baudy-Floc'h、Albert Robert
DOI:10.1055/s-1991-26562
日期:——
2-Substituted oxirane-1,1-dicarbonitriles react with water, alcohols or phenol to give 2-substituted 2-hydroxyacetic acids, alkyl 2-alkoxyacetates and phenyl 2-phenoxyacetates, respectively. Reaction of 2-substituted oxirane-1,1-dicarbonitrile with thiophenol and a nucleophile, typically water ethanol or urea, gave 2-(phenylthio)acetic acids, ethyl 2-(phenylthio)acetates and N-aminocarbonyl-2-(phenylthio)acetamides.
Urea-Induced Acid Amplification: A New Approach for Metal-Free Insertion Chemistry
作者:Erica D. Couch、Tyler J. Auvil、Anita E. Mattson
DOI:10.1002/chem.201403283
日期:2014.7.1
α‐aryldiazoacetates in high yield. This methodology was found to be generally applicable to a broad substrate scope and presents a conceptually newapproach for organocatalytic diazo insertion reactions. Mechanistic investigations suggest that the reaction pathway involves a urea‐induced protonation of the α‐aryldiazoester.
O–H and S–H insertion reactions of aryl- and diazo-substituted esters. Hydrogen-bond-donor catalysts enable a variety of formal insertion reactions of diazo compounds. The role of the catalyst in the reaction system may vary depending on several factors, including the nucleophilicity of the diazo compound and the acidity of the insertion partner. Ureas and phosphoric acid derivatives can offer complementary