Solvent-controlled retention or inversion of configuration in the Suzuki reaction of 2-bromo-1,3-dienes: Stereodivergent synthesis of trisubstituted conjugated alkenes

Suzuki coupling of 2-bromo-1,3-dienes with various boronic acids proceeds with retention or inversion of configuration of the Br-bearing double bond depending on the polarity of the solvent used. In toluene the retention products are obtained with up to >99:1 dr, while in DMA/MeCN the Suzuki reaction proceeds with the formation of the inversion products with up to 98:2 dr. This approach makes it possible to obtain E - and Z -trisubstituted conjugated alkenes starting from only one diastereomer of 2-bromo-1,3-dienes as cross-coupling partners.