Abstract The Peterson olefination reaction has been investigated as a route to novel P- substituted alkenes. The reaction between [(nPr 2 P) 2 (Me 3 Si) C] Li and paraformaldehyde cleanly gives the symmetrical vinylidene phosphane (nPr 2 P) 2 C= CH 2 (4) in good to excellent yields. In contrast, reactions between [(R 2 P)(Me 3 Si) 2 C] Li (R= Me, nPr) and paraformaldehyde yield complex mixtures of products which do not contain the expected ...
