Issue 13, 2024

DFT study of rhodium-catalyzed transformation of silacyclobutane with alkyne or H2O: Si–Cl bond reductive elimination vs. alkyne insertion

Abstract

Organosilicon compounds are essential structural units in organic synthesis, materials science, and drug molecule design. Despite significant strides in understanding the intramolecular C(sp2)–H/C(sp3)–H silylation mechanism, the intermolecular C(sp)–H/O–H silylation processes remain elusive. Here, density functional theory (DFT) calculations have been employed to uncover the mechanisms governing both the Rh/BINAP-catalyzed C(sp)–H silylation of silacyclobutane with alkyne and the O–H silylation of silacyclobutane with H2O. Our investigation yielded several crucial insights, including the following: (1) C(sp)–H silylation and O–H silylation undergo a similar catalytic cycle rather than previously proposed different catalytic cycles; (2) the [Rh]–H species resulting from the precatalyst [Rh]–Cl with silacyclobutane is identified as the real active species; (3) a refined [Rh]–H-catalyzed mechanism involves C–Si bond activation, C–H bond formation, C(sp)–H bond activation of alkyne/σ-bond metathesis of H2O, and C–Si bond reductive elimination. Simultaneously, the newly proposed reaction pathway sheds light on why silacyclobutane and alkyne yield distinct products in both the Rh/BINAP and Rh/PPh3 systems. This discrepancy stems from steric hindrance induced by BINAP during the alkyne insertion step, thereby favoring the Si–Cl bond reductive elimination.

Graphical abstract: DFT study of rhodium-catalyzed transformation of silacyclobutane with alkyne or H2O: Si–Cl bond reductive elimination vs. alkyne insertion

Supplementary files

Article information

Article type
Research Article
Submitted
10 Mar 2024
Accepted
05 May 2024
First published
08 May 2024

Org. Chem. Front., 2024,11, 3663-3674

DFT study of rhodium-catalyzed transformation of silacyclobutane with alkyne or H2O: Si–Cl bond reductive elimination vs. alkyne insertion

J. Li, W. Chen and S. Qu, Org. Chem. Front., 2024, 11, 3663 DOI: 10.1039/D4QO00440J

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