Sulfoxides as Stereochemical Controllers in Intermolecular Heck Reactions
摘要:
The study of a variety of substituted sulfoxides as chiral auxiliaries in intermolecular Heck reactions of sulfinyldihydrofurans and sulfinylcyclopentenes with different iodoarenes is reported. In the presence of [Pd(OAc)(2)]/Ag2CO3 and a bidentate phosphine ligand, synthetically useful yields and asymmetric inductions were obtained. By far the best diastereoselectivities were obtained by the use of the palladium-coordinating o-(N,N-dimethylamino)phenylsulfinyl group. By final removal of the chiral auxiliary, these sulfoxide-stereocontrolled asymmetric Heck processes were applied to the enantioselective synthesis of 1-aryl-substituted and 1,3-diaryl-substituted dihydrofurans and cyclopentenes.
Enantioselective Direct Vinylogous Michael Addition of Functionalized Furanones to Nitroalkenes Catalyzed by an Axially Chiral Guanidine Base
作者:Masahiro Terada、Kenichi Ando
DOI:10.1021/ol200415u
日期:2011.4.15
The highly syn-diastereo- and enantioselectivedirectvinylogousMichaeladdition of α-thio substituted furanones with conjugate nitroalkenes was demonstrated using an axially chiral guanidine base catalyst. The method provides facile access to enantioenriched α,γ-functionalized butenolides that can be further manipulated, thereby rendering them useful synthetic intermediates.