An efficient room temperature preparation of bromo difluorovinylzinc reagent (CF2CBrZnCl) and a high yield one-pot synthesis of α-bromo-β,β-difluorostyrenes

Facile synthesis of unsymmetrical 1,1-diaryl-2,2-difluoroethenes via stepwise coupling of 1,1-dibromo-2,2-difluoroethenes

“…MHz ( Spectral data for compounds 2a [10,11], 2b [12], 2d [12], and 2e [11] showed good agreement with the literature data. As for compounds 2a, 2b, 2d, and 2e, we present only NMR data in this section.…”

Room temperature preparation of α-chloro-β,β-difluoroethenylzinc reagent (CF2CClZnCl) by the metallation of HCFC-133a (CF3CH2Cl) and a high yield one-pot synthesis of α-chloro-β,β-difluorostyrenes

“…Based on this method, we have recently developed an excellent room temperature preparation of the trifluorovinylzinc reagent by the metallation of HFC-134a, and this reagent was utilized for Pd(0) catalyzed coupling reactions with aryl iodides to obtain a,b,b-trifluorostyrenes under mild reaction conditions [26,27]. We have then applied similar strategy for the synthesis of a-halo-b,b-difluorovinylzinc reagents [CF 2 CXZnX, where X = Cl, Br, I] and the corresponding a-halo-b,b-difluorostyreness by the metallation of the corresponding commercially available precursors [23,28,29]. This methodology serves as the first general methodology for the synthesis of a-halo-b,bdifluorovinylzinc reagents and corresponding a-halo-b,bdifluorostyrenes.…”

The first preparation of the α-iodo-β,β-difluorovinylzinc reagent (CF2CIZnCl) and a high-yield one-pot synthesis of α-iodo-β,β-difluorostyrenes

“…It was of interest to examine whether there are competing reactions resulting in two different zinc reagents during the metallation of CF 3 CH 2 I. Metallation at the hydrogen site was expected to produce the iodozinc reagent (CF 2 =CIZnCl), whereas metallation at the iodine site would result in the hydrozinc reagent (CF 2 =CHZnCl) [43]. Though metallation at the halogen sites was not observed in the LDA metallation of CF 3 CH 2 Cl and CF 3 CH 2 Br [41,42], metallation of the iodine site might be expected for CF 3 CH 2 I due to the more labile C-I bond. Thus, via the conditions standardized for the metallation of HFC-134a, a THF solution of CF 3 CH 2 I and anhydrous zinc chloride was treated with 2.0 equiv.…”

“…The vinyl zinc reagents thus generated were coupled with aryl iodides to produce a,b,b-trifluorostyrenes and a-chlorob,b-difluorostyrenes in excellent isolated yields (Scheme 4). An extension of this methodology was later applied for the synthesis of a-bromo-b,b-difluorostyrenes [42]. Here the a-bromo-b,b-difluorovinylzinc reagent (CF 2 =CBrZnCl), generated by metallation of CF 3 CH 2 Br or CF 2 =CHBr, was coupled with aryl iodides to produce a-bromo-b,bdifluorostyrenes (Scheme 5).…”