Rhodium-Catalyzed Synthesis of Silicon-Bridged 1,2-Dialkenylbenzenes via 1,4-Rhodium Migration

An efficient synthesis of 1,3-dialkylidene-2,3-dihydro-1H-benzo[c]siloles, a new type of silicon-bridged pi-conjugated compounds, was developed from a simple substrate combination of dialkynylsilanes and arylboronic acids under rhodium catalysis through the use of 1,4-rhodium migration. The reaction pathway was probed by deuterium labeling experiments, and the use of o-tolylboronic acids led to the formation of 6-membered silacycles via 1,5-rhodium migration.