Synthesis of Five-Membered Organoborate Heterocycles via a Metal-Free Carboboration and Their Use in Cross-Coupling Reactions

Treatment of various vinylbenzopyridines with allyl(dichloro)borane affords five-membered organoborate heterocycles via a metal-free carboboration. The reaction between these organoborates and Grignard reagents increases the number of derivatives belonging to this novel family of four-coordinate organoboron compounds. Some of them were used as reagents in phenylations and methylations in moderate to high yields under standard palladium-catalyzed cross-coupling reaction conditions.