Asymmetric γ-Deprotonation and Homoaldol Reaction of 1,3-Dien-2-yl Carbamates: Stereo- and Regiochemistry

Lithium compounds 7 are configurationally stable intermediates obtained by deprotonation of 1,3-dien-2-yl carbamates 6 with n-butyllithium/(−)-sparteine with a high degree of enantiotopic differentiation at the γ-position. They react with electrophiles regioselectively giving highly
enantioenriched products. Starting with different isomers or changing the double-bond geometries in 6 leads to either of the enantiomers.