A Versatile Synthesis of Substituted Benzimidazolium Salts by an Amination/Ring Closure Sequence
摘要:
[GRAPHICS]A new method to produce benzimidazolium salts based on a successive Buchwald-Hartwig amination and ring closure is reported. A variety of different benzimidazolium salts can be prepared using this procedure. Amines that bear an alpha -chiral group undergo the reaction to furnish chiral benzimidazolium salts. The salts that lack a C2 substituent on the heterocycle are readily deprotonated to give nucleophilic carbenes.
Synthesis of chiral N,N′-disubstituted 1,2-benzenediamines from o-dibromobenzene
摘要:
Palladium-catalyzed amination of o-dibromobenzene provided chiral N,N'-disubstituted 1,2-benzenediamines in good to excellent yields. The amination was executed stepwise and in one pot to give unsymmetrically and symmetrically substituted 1,2-benzenediamines. Incorporation of chiral primary amines was possible without racemization using catalytic Pd(2)dba(3)-BINAP. (C) 2000 Elsevier Science Ltd. All rights reserved.