It was found that lanthanum metal caused the dehalogenation of o-dihalogen substituted arenes and α, α′-dihalogen substituted o-xylenes to generate the corresponding benzynes and o-quinodimethanes. When o-dihalogen substituted arenes were allowed to react with lanthanum metal in the presence of dienes, the Diels–Alder products between benzyne and dienes were formed in moderate to good yields. Similarly, the Diels–Alder adducts of o- ...
