alpha-Metallierte Enäther als "Masken" für Acyl-Anionen

H2C:CHCH2OR (R = tetrahydropyranyl) gave a mixt. of H2C:CHCHR1OH and R1CHCH2CHO after metalation and reaction with an electrophilic agent R1X, whereas metalation of MeCH:CHOR (R = tetrahydropyranyl) with EtCHMeLi, followed by reaction with MeI and acid hydrolysis gave EtCOMe. The electrophile in the latter case could also be an alkyl halide, oxirane, carbonyl compd., nitrile, or CO2. [on SciFinder (R)]