Wittig reactions of the ylide (Ph3P+CH-)2CH2 (I) with aliphatic aldehydes and ketones are described. A soln. of I in THF prepd. from (Ph3P+CH2)2CH2.2Br- was treated with an equimolar amt. of geranylacetone to give a stereoisomeric mixt. of II (norsqualene), b0.001 172-4 Deg, in 25% yield. III, b1 114-17 Deg, was similarly prepd. from I and cyclohexanone in 37% yield. I and propanal gave 49% (EtCH:CH)2CH2, b.142-5 Deg, contg. >90% cis, cis isomer, while the reaction in the presence of LiBr gave 35:50:15 mixt. of cis,cis,cis,trans, and trans,trans isomers, resp. [on SciFinder (R)]