摘要:
Benzyne reacts with enamines through a combination of ene and 2 + 2 cycloadditions. One of the two possible ene reactions is greatly favored. The three-dimensional intermediate, 1,2-dehydro-o-carborane, 1 eschews the 2 + 2 reaction in favor of the ene reaction that is less favored in the benzyne reactions. This preference is rationalized in terms of the different steric demands of the two intermediates.