New Efficient Approach to 2,2-Diaryl-1,1-difluoro-1-alkenes and 1,1-Difluoro-2-aryl-1,3-dienes via Suzuki Coupling of α-Halo-β,β-difluorostyrenes
摘要:
[Graphics]a-Halo-beta,beta-difluorostyrenes [ArCX = CF2; X = Br, I; Ar = aryl, heteroaryl; synthesized by the Pd(0)-catalyzed coupling reaction of the corresponding alpha-halo-beta,beta-difluoroethenylzinc reagents (CF2=CXZnCl, X = Br, I) with aryl iodides] were functionalized at the halogen site with arylboronic acids under Pd(0)-catalyzed Suzuki-Miyaura coupling reaction conditions to obtain 2,2-diaryl-1,1-difluoro-1-alkenes (ArAr'C=CF2, Ar' = aryl, heteroaryl) in 51-91% isolated yield. The corresponding reaction with alkenylboronic acids produced 1,1-difluoro-2-aryl-1,3-dienes in 53-80% isolated yield. Alternatively, 2,2-disubstituted-1,1-difluoro-1-alkenes were synthesized in moderate yield by a zinc-insertion reaction at the halogen site of the alpha-halo-beta,beta-difluorostyrenes, followed by Pd(0)-catalyzed cross-coupling of the zinc reagent with aryl or alkenyl iodides.
An efficient room temperature preparation of bromo difluorovinylzinc reagent (CF2CBrZnCl) and a high yield one-pot synthesis of α-bromo-β,β-difluorostyrenes
作者:R. Anilkumar、Donald J. Burton
DOI:10.1016/j.jfluchem.2003.11.029
日期:2004.4
A high yield room temperature preparation of the1-bromo-2,2-difluorovinylzinc reagent [CF2CBrZnCl] (>89%) was achieved via insitu metallation of CF3CH2Br or CF2CHBr with LDA in presence of ZnCl2. Palladium catalyzed cross-coupling of this zinc reagent with aryl iodides provides α-bromo-β,β-trifluorostyrenes (ArCBrCF2) in 64–86% isolated yields, in an essentially ‘one-pot’ procedure.