Two domino reactions of vinylcyclopropyl oxime ethers involving (i) thiyl radical addition, ring-opening, and hydroxylation reactions and (ii) thiyl radical addition, ring-opening, and aldol-type reactions were developed.
Olefins undergo cyclopropanation with diphenylsulfonium (ethoxycarbonyl)methylide (= diphenylsulfonium 2-ethoxy-2-oxoethylide; 3a) in the presence of chiral Cu-I or Rh-II catalysts, trans/cis Ratios and ee's of the cyclopropanes 6 obtained with this ylide in the presence of a chiral Cu-I catalyst 7 are identical with those obtained with ethyl diazoacetate (4). In the case of catalysis with Rh-II, the trans/cis ratios of the cyclopropanes as well as the enantioselectivity change slightly upon going from the ylide 3a to diazoacetate 4.
Extremely Efficient Chiral Induction in Conjugate Additions of <i>p</i>-Tolyl α-Lithio-β-(trimethylsilyl)ethyl Sulfoxide and Subsequent Electrophilic Trapping Reactions
Reaction of p-tolyl alpha-lithio-beta-(trimethylsilyl)ethyl sulfoxide with alpha,beta-unsaturated esters gave the conjugate addition products as a single diastereomer. The intermediate enolates were subsequently trapped with various alkyl halides or aldehydes to give the products with extremely high stereoselectivity. The reaction with alpha,beta-unsaturated ketones also proceeded with high diastereoselectivity