On the mechanism of the nickel-catalysed regioselective cyclodimerization of isoprene
作者:P.W.N.M. van Leeuwen、C.F. Roobeek
DOI:10.1016/s0040-4020(01)97949-9
日期:——
similar steric properties the changes in product distribution as a function of the electronic ligand parameter are explained in terms of a gradual change in HOMO-LUMO interactions between Ni and the olefins, with strong π-acidic ligands promoting the head-to-headcoupling of the isoprene molecules. The second step, involving reductive elimination of a cyclodimer from the metal, shows an increasing selectivity
Ylures sans sel, evolution en phosphoranes et equilibre ylure ⇌ phosphorane
作者:R. Burgada、Y.O. El Khoshnieh、Y. Leroux
DOI:10.1016/s0040-4020(01)96522-6
日期:1985.1
phoiphoranes , , , , , to by addition of a trivalent phosphorus compound (phosphites and amino-phosphines ) to with dimethyl acetylencedicartboxylate in presence of a protic trapping reagent are described. The results are consistent with trapping of carbanionic species. In relation with the. cyclic of acyclic structure of the triivalent phosphorus compound and the protic trapping reagent ie : methanol, phenol