Ring Expansion to 8‐Membered Silacycles through Formal Cross‐Dimerization of 5‐Membered Palladacycles with Silacyclobutanes

• Published in: European journal of organic chemistry 2021-06, Vol.2021 (21), p.3039-3042
• Main Authors: Wang, Xi–Chao, Wang, Hao‐Ran, Xu, Xiufang, Zhao, Dongbing
• Format: Article
• Language: English
• Subjects: C−H bond activation; C−Si bond cleavage; Dimerization; Lead compounds; Palladium catalysis; Ring expansion; Silacycle
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.202100535

Investigations of the sila‐8‐membered ring fused biaryls are of high significance for the discovery of new drug lead compounds. However, such compounds are still unknown due to the synthetic challenge. Herein, we describe the chemo‐ and regio‐selective cross‐dimerization of 5‐membered palladacycles with silacyclobutanes enabled by Pd‐catalytic conditions, which constitutes an expedient ring expansion route to the sila‐8‐membered ring fused biaryl skeletons. Described herein, the chemo‐ and regio‐selective ring expansion of silacyclobutanes to sila‐8‐membered ring fused biaryl skeletons, enabled by Pd‐catalytic conditions. This strategy involves C−C bond cleavage or C(sp2/sp3)−H bond activation and C−Si bond cleavage followed by a double reductive elimination process. DFT calculations indicate that the C−H bond activation or C−C bond cleavage to form palladacycle species is more energetically favourable than C−Si bond cleavage of silacyclobutanes at the beginning.