Asymmetric wittig reaction of chiral arsonium ylides—I. Asymmetric olefination of 4-substituted cyclohexanones
作者:Wei-Min Dai、Jinlong Wu、Xian Huang
DOI:10.1016/s0957-4166(97)00223-1
日期:1997.6
Asymmetric Wittig-type olefination of 4-substituted cyclohexanones with chiral ligand-modified stable arsonium ylides has been examined. The 8-phenylmenthol-derived chiral arsonium ylide of 4 reacted with prochiral ketones 9a-d at −15°C to give the 4-substituted cyclohexylideneacetates 11a-d in 58–69% yield and in up to 80% diastereomeric excess (de).
The asymmetric Horner-Emmons reaction using a benzopyrano-isoxazolidine auxiliary
作者:Atsushi Abiko、Satoru Masamune
DOI:10.1016/0040-4039(95)02352-6
日期:1996.2
The asymmetricHorner-Emmonsreaction of the phosphonate derived from a chiral benzopyrano-isoxazolidine (with 4-substituted cyclohexanones) proceeded in high diastereoselectivity with the aid of KHMDS and 18-crown-6 ether. Enantiomerically pure, axially dissymmetric cyclohexylidene alcohols, aldehydes and ketones were obtained from the diastereomerically pure Horner-Emmons products in a single step