Stereoselective coupling of optically active 3-trans-cinnamoyl-2-oxazolidinones with acid anhydrides by electroreduction
摘要:
The electronduction of chiral 3-trans-cinnamoyl-2-oxazolidinones with acid anhydrides gave beta-acylated products stereoselectively. The products were transformed to optically active cis-beta,gamma-disubstituted-gamma-lactones. (C) 1999 Elsevier Science Ltd. All rights reserved.
metathesis reactions allows for a stereoselective subsequent RuO4-catalyzed dihydroxylation. The sequence is concluded by an unusual kinetic resolution of the diastereomeric diols obtained in the oxidation reaction. As a consequence a variety of structurally diverse enantiomerically enriched diols are obtained. To the best of our knowledge the results summarized in this paper represent the first highly efficient
Enantioselective synthesis of dimethyl 3,4-diphenyladipate by electroreductive hydrocoupling of chiral N-trans-cinnamoyl-2-oxazolidones
作者:Naoki Kise、Mitsuaki Echigo、Tatsuya Shono
DOI:10.1016/s0040-4039(00)73190-x
日期:1994.3
Dimethyl(3R,4R)- and (3S,4S)-diphenyladipate were synthesized enantioselectively by electroreductive intermolecular hydrocoupling of chiral N-trans-cinnamoyl-2-oxazolidones and subsequent methanolysis.
Stereoselective Hydrocoupling of Optically Active 3-<i>trans</i>-Cinnamoyloxazolidinones by Electroreduction
作者:Naoki Kise、Syun-ichiro Mashiba、Nasuo Ueda
DOI:10.1021/jo981231f
日期:1998.10.1
Reductive hydrocoupling of chiral 3-trans-cinnamoyloxazolidinones was studied by an electro chemical method. The electroreduction was performed conveniently at a constant current using an undivided cell. The stereoselectivity of the hydrodimers was strongly affected by the electrolyte employed. Electroreduction of (S)-4-isobutyl-3-trans-cinnamoyloxazolidinone 1a in 0.3 M Et4NOTs/AN gave a mixture of two diastereomers of all-trans cyclized hydrodimer 2a, and the selectivity was R,S,R/S,R,S = 85:15. On the other hand, the reduction of 1a in 1.7 M LiClO4/THF afforded a diastereomeric mixture of hydrodimers in a selectivity of R,R/S,S/R,S = 5:52:43. The stereoselectivities were explained by considering stable conformations of intermediate anion radicals, that is, syn-Z type for naked anion radicals and anti-Z type for lithiated anion radicals. Semiempirical calculations also supported this hypothesis. Electroreductions of (S)-4-isobutyl-3-cis-cinnamoyloxazolidinone and (S)-4-isobutyl-3-phenylpropioloyloxazolidinone gave 2a in the same stereoselectivity as electroreduction of 1a did. The electroreductive hydrocoupling was not inhibited by para and meta substitution on the aryl group of 3-trans-cinnamoyloxazolidinones. An ortho substitution, however, hindered the hydrocoupling and lowered the stereoselectivity of the hydrodimers. Electroreduction of 3-trans-cinnamoyloxazolidinethione and thiazolidinethione gave trans-3,4-diphenylcyclopentanone as a product, and the stereoselectivities were similar to that obtained from the corresponding oxazolidinone.