Phosphor-Betaine als Wittig-Zwischenstufen : Es gibt sie doch !
Phosphorus ylides combine with carbonyl compds. to give zwitterionic betaines as detectable intermediates of the Wittig reaction, provided that the neg. charge on the O atom was substantially reduced by binding to a Li cation or resonance delocalization into an adjacent carbonyl group. Thus, Bu3P+Me I- was lithiated to give Bu3P+CH2-.LiI, which, with Ph2CO gave Bu3P+CH2CPh2OLi I- which, at room temp., decomposed to give Bu3PO and 1,1-diphenylethylene. Lithiation of Bu3P+CH2CPh2OH I- gave I. The reaction of Ph3P+C-Me2 with Ph2C:C:O, tert-butyl isocyanate, and CO2 gave II which was in equil. with Ph3P+CMe2C(:X)O- (X = CPh2, NCMe3, O). [on SciFinder (R)]
Keywords: Wittig reaction (of phosphorus betaines); Betaines Role: RCT (Reactant) ; RACT (Reactant or reagent) (phosphorus ; as Wittig intermediates); Ylides Role: RCT (Reactant) ; RACT (Reactant or reagent) (phosphorus ; reaction with carbonyl compds.) ; phosphorus betaine; Wittig intermediate phosphorus betaine; ylide phosphorus
Organometallic and Organometalloidal Compounds
Inst. Chim. Org.,Univ. Lausanne,Lausanne,Switz.
written in German.
1702-42-7; 64435-18-3 Role: RCT (Reactant), RACT (Reactant or reagent) (lithiation of); 530-48-3P; 814-29-9P; 16666-80-1P; 53213-13-1P; 64422-85-1P; 64422-86-2P; 64435-07-0P; 64435-10-5P; 64435-11-6P; 64435-12-7P; 64435-13-8P; 64435-14-9P; 64435-15-0P; 64435-16-1P; 64435-17-2P; 64470-11-7P Role: SPN (Synthetic preparation), PREP (Preparation) (prepn. of); 20262-14-0 Role: RCT (Reactant), RACT (Reactant or reagent) (reaction with ketenes, isocyanates, and carbon dioxide); 124-38-9; 525-06-4; 1609-86-5 Role: RCT (Reactant), RACT (Reactant or reagent) (reaction with phosphorus ylides)
Record created on 2006-03-03, modified on 2016-08-08