Stereoselective syntheses of beta,gamma-unsaturated esters and gamma-lactones: 1-(Benzotriazol-1-yl)-3-(diphenylphosphoryl)-1-ethoxy-1-propene, a protected =CCH2CO2Et synthon equivalent

1-(Benzotriazol-1-yl)-3-(diphenylphosphoryl)-1-ethoxy-1-propene (3), prepared from N-(alpha-ethoxy-allyl)benzotriazole (1), underwent selective Horner reactions with aldehydes to give substituted dienes. Subsequent hydrolysis of these intermediates readily produced beta,gamma-unsaturated esters 2a-c in good yields. Similar reactions with ketones followed by hydrolysis of 10 produced, depending on the conditions, either the corresponding gamma,gamma-disubstituted beta,gamma-unsaturated esters 11a-d or gamma-lactones 9a-c and 13. A double lithiation process provided beta,gamma,gamma-trisubstituted beta,gamma-unsaturated esters 15, 18, and beta,gamma,gamma-trisubstituted gamma-lactone 14.