Donor/Acceptor-Stabilized 1-Silaketene: Reversible [2+2] Cycloaddition with Pyridine and Evolution by an Olefin Metathesis Reaction.
The reaction of silacyclopropylidene 1 with benzaldehyde generates a 1-silaketene complex 2 by a formal atomic silicon insertion into the C=O bond of the aldehyde. The highly reactive 1-silaketene 2 undergoes a reversible [2+2] cycloaddition with pyridine to give sila-β-lactam 3. Of particular interest, in the presence of 4-dimethylaminopyridine (DMAP), 1-silaketene complex 2 evolves through an intramolecular olefin metathesis reaction, generating a new 1-silaketene complex 8 and cis-stilbene. Theoretical studies suggest that the reaction proceeds through the formation of a transient silacyclobutanone, a four-membered-ring intermediate, similar to that proposed by Chauvin and co-workers for the transition-metal-based olefin metathesis.
Université de Toulouse, UPS, and CNRS, LHFA UMR 5069, 31062, Toulouse, France.
Morelia Lopez
ML
Reyes
Université de Toulouse, UPS, and CNRS, LHFA UMR 5069, 31062, Toulouse, France.
Thibault
T
Troadec
Université de Toulouse, UPS, and CNRS, LHFA UMR 5069, 31062, Toulouse, France.
Ricardo
R
Rodriguez
Université de Toulouse, UPS, and CNRS, LHFA UMR 5069, 31062, Toulouse, France.
Antoine
A
Baceiredo
Departament de Química, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain.
Nathalie
N
Saffon-Merceron
Université de Toulouse, UPS, and CNRS, ICT FR2599, 118 route de Narbonne, 31062, Toulouse, France.
Vicenç
V
Branchadell
Université de Toulouse, UPS, and CNRS, LHFA UMR 5069, 31062, Toulouse, France. kato@chimie.ups-tlse.fr.
Tsuyoshi
T
Kato
1-silaketene; atomic silicon insertion; olefin metathesis; silanone; transition-metal-like behavior