Oxovanadium(V)-induced oxidative transformations of main-group organometallics

Abstract

Oxovanadium(V) compounds induce one-electron oxidative desilylation of organosilicon compounds such as silyl enol ethers, allylic silanes, and benzylic silanes, permitting chemoselective coupling with the less oxidizable organosilicon compounds. The oxovanadium(V)-induced oxidation of benzylsilane and benzyltin compounds is carried out under an oxygen atmosphere to afford the aromatic aldehydes (ketones) and/or carboxylic acids. The catalytic reaction proceeds with benzyltins. Oxidative ligand coupling of dialkylarylaluminums is achieved by treatment with oxovanadium(V) compounds, leading to the formation of the alkylarenes. The ate complex derived from 1-alkenyllithium and arylaluminum or 1-alkenylaluminum undergoes the more facile oxidation to give the corresponding ligand coupling product selectively. The similar oxidation of organoborons or ate complexes also results in the oxidative coupling of organic groups on boron. This method is applied to the oxidative ligand coupling of organozinc compounds and ate complexes. In particular, the organozincates prepared from iodoarenes and Me 3ZnLi or bromoarenes and Me 4ZnLi 2 are oxidized with higher selectivity. Vicinal alkylation with diorganozincs or ate complexes at both the α and β positions of 2-cycloalkenones is performed by treatment with oxovanadium(V) compounds.