The chemical behavior of three-membered ring heterocycles is mostly dictated by the release of the ring strain as the main driving force, with a strong influence both of the nature of the embedded heteroelement and of the degree of unsaturation of the cycle. The palladium-catalyzed annulation reaction of terminal alkynes with a silirene enables a general approach to siloles involving reactive intermediates that have remained elusive to date. The first objective of the work is to understand this chemical process that enables the incorporation of a terminal alkyne into the starting unsaturated three-membered silicon heterocycle.
The reaction was experimentally studied and also apprehended thanks to theoretical calculations carried out at the DFT-B3PW91 level of theory. The annulation reaction of alkynes with silirene occurs in three main steps, involving (i) the OA of Pd(0) to the silirene with formation of the elusive 1,2-palladasilacyclobutene which could be isolated for the first time; (ii) the insertion of the alkyne into the Pd−Si bond that operates chemo- and regio-selectively, and (iii) the reductive elimination on the 1,4-palladasilacyclohexadiene compound with the exothermic release of the silole product.
Reference
- Marc Devillard,* Chiara Dinoi, Iker Del Rosal, Clément Orione, Marie Cordier, and Gilles Alcaraz*
Inorg. Chem., 2023, https://doi.org/10.1021/acs.inorgchem.3c00045
Contact
- Marc Devillard, Univ. Rennes, CNRS, ISCR - UMR 6226, F-35000 Rennes, France
marc [dot] devillard
univ-rennes [dot] fr
- Gilles Alcaraz, Univ. Rennes, CNRS, ISCR - UMR 6226, F-35000 Rennes, France
gilles [dot] alcarazuniv-rennes [dot] fr
Published May 12, 2023
