Consecutive treatment of endo-butenylpotassium or endo-1-(tetrahydropyranyloxy)-exo-butenyllithium with FB(OMe)2 and pentanal at -75 Deg affords an erythro- and, threo-adduct, resp., which on hydrolysis and oxidn. lead to cis- and, trans-5-butyl-4-methyl-t ...
1984