Aromatic Amination/Imination Approach to Chiral Benzimidazoles
摘要:
The powerful Buchwald-Hartwig amination was utilized for the construction of the benzimidazole nucleus with the substituted nitrogen atom bearing a chiral substituent. A successive amination/imination was followed by an acid-catalyzed ring closure step to give the benzimidazole ring. The products were deprotonated and acylated at the C2 position and could be alkylated on nitrogen to give chiral benzimidazolium salts.
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.