Enantioselective Acyloin Rearrangement of Acyclic Aldehydes Catalyzed by Chiral Oxazaborolidinium Ion
作者:Soo Min Cho、Si Yeon Lee、Do Hyun Ryu
DOI:10.1021/acs.orglett.1c00314
日期:2021.2.19
A catalytic enantioselective acyloin rearrangement of acyclic aldehydes to synthesize highly optically active acyloin derivatives is described. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction provided chiral α-hydroxy aryl ketones in high yield (up to 95%) and enantioselectivity (up to 98% ee). In addition, the enantioselective acyloin rearrangement of α,α-dialkyl-α-siloxy
Ready Access to Densely Substituted Furans Using Tsuji–Wacker-Type Cyclization
作者:Dattatraya P. Masal、Rahul Choudhury、Aman Singh、D. Srinivasa Reddy
DOI:10.1021/acs.joc.1c02567
日期:2022.1.7
construction of highly substitutedfurans catalyzed by Pd(II) and Cu(II) chloride has been developed. The method provides easy access to di-, tri-, and tetrasubstituted furans from corresponding diols with relatively mild conditions in a unified strategy. The developed method has been successfully tested with more than 25 substrates, which resulted in furans of multiple substitution patterns with up to
An enantiospecific synthesis of (S)- and (R)-(E)-5-[1,3-diphenyl-2-(imidazol-l-yl)propylidene] aminooxypentanoic acids 1 using homochiral phenylalanines as starting material is described. Chiral alpha-hydroxyketones 9 were obtained from alpha-hydroxyacids 7 by Weinreb's ketone synthesis. Imidazole introduction by nucleophilic substitution on mesylate 10 led to 2-(imidazol-1-yl)propan-1-one derivative 3, key intermediate in the synthesis of 1. However, the low configurational stability displayed by compound 3 compromised its use in an enantiospecific synthesis. Homochiral compounds 1 were then obtained by a nucleophilic substitution on alpha-mesyloxy-O-alkyloxymes 14 which were in turn obtained from 9. This nucleophilic substitution on alpha-mesyloxy-O-alkyloxymes was not previously reported either on homochiral compounds or on racemic derivatives. (C) 1997 Elsevier Science Ltd.