Stereospecific Cross-Coupling of Secondary Organotrifluoroborates: Potassium 1-(Benzyloxy)alkyltrifluoroborates

Reaction Scheme


The synthesis of potassium trifluoro(N-methylheteroaryl)borates and their use in cross-coupling reactions with various aryl and heteroaryl halides to construct N-methyl heteroaryl-substituted aromatic and heteroaromatic compounds are reported.



A 10 mL microwave vial equipped with a stirrer bar was charged with trifluoro(N-methylheteroaryl)borate (0.55 mmol), Cs2CO3 (0.4887 g, 1.5 mmol, 3 equiv), (hetero)aryl halide (0.5 mmol), Pd(OAc)2 or [PdCl(allyl)]2 (0.025 mmol, 5 mol %), and RuPhos or SSPhos (0.05 mmol, 10 mol %), and then sealed with a cap lined with a disposable PTFE septum. The vial was then evacuated under a vacuum and purged with Ar (3 times). Ar-purged CPME (2 mL) and H2O (0.5 mL) were added by syringe [(hetero)aryl halides that were liquids at room temperature were added by syringe], and the reaction mixture was stirred and heated at 100 �C for 24 h and then cooled to rt and diluted with H2O (5 mL). The reaction mixture was extracted with EtOAc (5 � 3 mL). The combined organics were dried (MgSO4), filtered through Celite, and concentrated in vacuo. All products were purified by column chromatography.



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