Enantioselective Synthesis of Homoallylic Alcohols

Much work has been done during the last decade on the synthesis of optically active alcohols by the enantioselective addition of an alkyl or aryl metallic species (Grignard, lithio or cuprous derivatives) to aldehydes or ketones in the presence of a chiral auxiliary able to complex the metallic species (1). Generally, the optical yields range up to 20 % using readily available chiral auxiliaries (N-methyl ephedrine, sparteine, glucofuranoses derivatives, etc…); however, better enantioselectivity (22–92 %) can be obtained by using more sophistacated ligands derived in several steps from proline or from 2. 2′-dicarboxy-1. 1′-dinaphtyl (2).