Reactions of pentaphenylborole with main group hydrides

The reactivity of the anti-aromatic pentaphenylborole with HBpin (pinacolborane), HGeEt3, and HSnBu3 was investigated. In all cases the products were 1-bora-cyclopent-3-ene heterocycles resulting from the stereospecific addition of the E-H bond to the borole. Both HGeEt3, and HSnBu3 furnished syn products, while the reaction with pinacolborane yielded the anti product.31