The successful couplings of electron-deficient, vinyl and heteroaromatic boronic acids (entries 4, 6 and 7, respectively) are noteworthy. The 3-pyridyl case (entry 7) required use of the more active catalyst 7 - this catalyst was originally developed for couplings of less reactive but more widely available aryl chlorides. [11] We also found that using the more stable diethyl-3-pyridylborane gave a better yield than either a glycol boronate ester (poor conversion in a small scale ...
