Practical approach to alpha- or gamma-heterosubstituted enoic acids.
The reaction of alkenyl trichloromethyl carbinols with various nucleophiles under protic basic conditions reveals that mercaptans participate by alpha-substitution (S(N)2) of the intermediate alkenyl gem-dichloroepoxides. Conversely, hydroxide results in preferential gamma-substitution with stereoselective allylic transposition (S(N)2'). Regioselectivity with alkoxides depends upon the level of alkene substitution. [reaction: see text]
Shamshina
Julia L
JL
Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, AL 34587-0336, USA.
Snowden
Timothy S
TS