Pan Y, Holmes CP, Tumelty D. Novel α,α-Difluorohomophthalimides via Copper-Catalyzed Tandom Cross-Coupling−Cyclization of 2-Halobenzamides with α,α-Difluoro Reformatskii Reagent.
J Org Chem 2005;
70:4897-900. [PMID:
15932341 DOI:
10.1021/jo050599r]
[Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Novel alpha,alpha-difluorohomophthalimides 2 were prepared by reacting N-substituted 2-halobenzamides with the alpha,alpha-difluoro Reformatskii reagent BrZnCF2CO2Et (3) in the presence of CuBr at room temperature. The synthesis involves a CuBr-mediated cross-coupling of 3 with aryl iodides or activated aryl bromides, followed by a spontaneous cyclization of the ethyl 2-benzamido-alpha,alpha-difluoroacetate intermediates at room temperature. N-unsubstituted alpha,alpha-difluorohomophthalimides 2 (R' = H), bearing an acidic imide proton capable of acting as a carboxylic acid bioisostere, were also prepared by reacting 3 equiv of 3 with the parent 2-iodobenzamides. Other aryl iodides such as 3-iodo-imidazo[1,2-alpha]pyridine were also used for the tandem coupling-cyclization reaction.
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