Cooperative Activation of Isocyanates by Al-N-Based Active Lewis Pairs and the Generation of a C Chain by Simultaneous Formation of Two C-C Bonds.

The active Al/N Lewis pair, (Me C) Al-C(SiMe )=C(H)-N(CHMe-CH ) CH (2), reacted with isocyanates to afford a fascinating variety of products. One equivalent of Ph-N=C=O yielded by the release of H-C≡C-SiMe an urea-type ligand which coordinated the Al atom in a chelating manner (4). Dipp-N=C=O gave a similar product, but the bulky substituent hindered the approach of the N-aryl group to Al.