Asymmetric Synthesis via Acetal Templates. 13. Preparation of Aldol Compounds from Butane-1,3-diol Acetals

Article abstract of DOI:10.1021/jo00378a004

The acetals 8, derived from (3S)-butane-1,3-diol, undergo TiCl4-catalyzed coupling with acetone trimethylsilyl enol ether (11) to give the aldol ethers 12/13 in high yield and diastereoselectivity in favor of 12 (Table I).The chiral auxiliary is readily removed from 12 by oxidation to the aldehyde 14 followed by selective β-elimination under conditions (dibenzylammonium trifluoroacetate) to which the aldol product 16 is stable (Table II).This methodology has been applied to an efficient asymmetric synthesis of (2R,4S)-oct-7-ene-2,4-diol (enantio-5), a key intermediate in the synthesis of nonactic acid.