Regiospecific Methylalumination of Silacyclopropenes: The Access to Z-1-Silyl-2-Aluminyl-Disubstituted Olefins

A methodology to access Z-1-silyl-2-aluminyl-disubstituted olefins is developed. It relies on the uncatalyzed ring opening of silacyclopropenes in the presence of a stoichiometric amount of trimethylaluminum. The resulting heterosubstituted alkenes exhibit a particular interaction between the electron-rich [Si-CH₃] moiety and the electron-deficient diorganoaluminyl group, resulting in similar geometrical features due to the proximity of these two centers. This interaction is rationalized using experimental and theoretical descriptors. The regioselectivity and functional tolerance of the methylalumination were also studied in the case of unsymmetrical silacyclopropenes, and the methodology ultimately transposed to the synthesis of a polymeric organoalane incorporating tricoordinated aluminum centers.