Reaction of aliphatic halides BrCH2-(CH2) n-CH2Br (n= 0, 2, 3) and α, α'-dibromo o-xylene with acetone-1, 3 diphosphorane gives, after hydrolysis, cyclopropyl, cyclopentyl, cyclohexyl, and indanyl-carbonylmethýlenètriphénylphosphoranes; cycloalkylcetones are obtained from these ylides by Wittig reaction or hydrolysis. Condensation of di-iodomethane leads to δ- diketonic compounds.