A new Ti-catalyzed cross-cyclomagnesiation of aliphatic and
oxygenated 1,2-dienes with EtMgBr in the presence of Cp2TiCl2
was used in the key stage for the development for the first
time original methods for the preparation of racemic and
natural neuritogenic alkynes lembehyne B and stereoselective
syntheses of (4Z,8Z)-pentacosa-4,8-dien-1-ol - the key intermediate
in the total synthesis of lembehyne A.