反应详情

Compounds of formula XX may be prepared by hydrolysis under alkaline conditions of compounds of formula XIX. Compounds of formula XXI may be obtained by the acetylation of compounds of formula XX under mild conditions and may be converted into compounds of formula XXII by reaction with a dihydropyran, dihydrofuran or ethyl vinyl ether in an inert solvent, e.g. methylene chloride, in the presence of a condensing agent, e.g. p-toluenesulphonic acid. Compounds of formula XXIII may be prepared by reducing compounds of formula XXII with diisobutylaluminium hydride in toluene for about 15 minutes at -60° C. Dimsyl anion, previously prepared from sodium hydride and dimethyl sulphoxide, is reacted with (4-carboxybutyl)triphenylphosphonium bromide to form (4-carboxybutylidene)triphenylphosphorane. To that compound is added a compound of formula XXIII and the mixture in dimethyl sulphoxide is made to react for 2 hours at room temperature to yield a compound of formula XVA.

1. customfor about 15 minutes
2. customat -60° C