Homocoupling of alkyl-, alkenyl-, and arylboronic acids

Alkyl-, alkenyl-, and arylboronic acids undergo Ag2O/CrCl2, mediated homocoupling in moderate to good yields under mild conditions. The general utility of this methodology is illustrated by an intramolecular annulation between sp and sp(3) centers. (C) 2002 Published by Elsevier Science Ltd.