Palladium catalyzed Suzuki-Miyaura cross-coupling reactions of potassium organotrifluoroborates: Enantiomerically enriched potassium β-trifluoroboratoamides and protected aminomethyl trifluoroborates.

Abstract

Potassium organotrifluoroborates are more stable to air and moisture than other boron-based derivs., such as boronic acids and boronate esters. Potassium organotrifluoroborates have been studied as alternative coupling partners in Suzuki-Miyaura cross-coupling reactions, providing less protodeboronation compared to their boronic acid/boronate counterparts. Therefore, only stoichiometric amts. or slight excesses of potassium organotrifuoroborates are required. Boron homoenolates have been studied in our lab. Compared to many other β-metallo homoenolates, potassium β-trifluoroboratoamides are more easily prepd. and tolerant of many functional groups. Enantiomerically enriched α-chiral β-trifluoroboratoamides using pseudoephedrine as the chiral auxiliary have been synthesized and validated as good coupling partners in Suzuki coupling reactions. Addnl., to provide the widely encountered primary aminomethyl structures, Boc-protected aminomethyl potassium trifluoroborates have been investigated for Suzuki coupling reactions with aryl- and heteroaryl chlorides. [on SciFinder(R)]