Studies on the Pd-catalyzed dimerization of silacyclobutanes

Ring Expansion toward Disila-carbocycles via Highly Selective C-Si/C-Si Bond Cross-Exchange

Herein, we successfully inhibited the preferential homodimerization and C-Si/Si-H bond cross-exchange of benzosilacyclobutenes and monohydro-silacyclobutanes and achieved the first highly selective C-Si/C-Si bond cross-exchange reaction by deliberately tuning the Ni-catalytic system, which constitutes a powerful and atom-economical ring expansion method for preparing medium-sized cyclic compounds bearing two silicon atoms at the ring junction, which are otherwise inaccessible. The DFT calculation explicitly elucidated the pivotal role of Si-H bond at silacyclobutanes and the high ring strain of two substrates in realizing the two C-Si bonds cleavage and reformation in the catalytic cycle.

3-Silaazetidine: An Unexplored yet Versatile Organosilane Species for Ring Expansion toward Silaazacycles

Small-ring silacycles are important organosilane species in main-group chemistry and have found numerous applications in organic synthesis. 3-Silaazetidine, a unique small silacycle bearing silicon and nitrogen atoms, has not been adequately explored due to the lack of a general synthetic scheme and its sensitivity to air. Here, we describe that 3-silaazetidine can be easily prepared in situ from diverse air-stable precursors (RSO₂NHCH₂SiR¹₂CH₂Cl). 3-Silaazetidine shows excellent functional group tolerance in a palladium-catalyzed ring expansion reaction with terminal alkynes, giving 3-silatetrahydropyridines and diverse silaazacycle derivatives, which are promising ring frameworks for the discovery of Si-containing functional molecules.