Dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes with lanthanum metal
摘要:
It was found that lanthanum metal caused the dehalogenation of o-dihalogen substituted arenes and alpha,alpha'-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-quinodimethane with dienophiles were obtained, in the reaction of alpha,alpha'-dibromo-o-xylenes with lanthanum metal in the presence of dienophiles. (C) 2003 Elsevier Ltd. All rights reserved.
A new generation method of benzyne has been developed. When 1,2-dihalogen substituted arenes were allowed to react with lanthanum metal in the presence of dienes, Diels–Alder products between benzyne and dienes were formed in moderate to good yields.