HIGHLY SELECTIVE ALLYLATION OF ALKYL METHYL KETONES IN THE PRESENCE OF CHIRAL 2-AMINO ALCOHOL DERIVATIVES

The facial selective allylation of alkyl methyl ketones 1a-f in the pr esence of chiral 2-amino alcohol derivatives 2a-p by reaction with all ylsilane 3 and a catalytic amount of TfOH to give the tertiary homoall ylic ethers 8a-o and 9a-e is described. The best results were obtained with the 2-amino alcohol derivative 2p which affords a stereoselectiv ity of 18:1 even for the allylation of ethyl methyl ketone. The ethers 8 and 9, which contain a phenyl group at C-1 of the amino alcohol moi ety, can be cleaved to give the corresponding homoallylic alcohols 5 b y reduction with sodium or Lithium in liquid ammonia.