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

Abstract

(J. Ichikawa). Abstract Unsymmetrical1,1-diaryl-2,2-difluoroethenes were synthesized from 1,1-dibromo-2,2-difluoroethene, which is commercially available, via the Suzuki-Miyaura coupling in a stepwise fashion. Suitable ligands for each coupling process were used to achieve selective synthesis of these diaryldifluoroethenes.

Method for the Synthesis of Dibenzo[g,p]Chrysenes: Domino Friedel–Crafts-Type Cyclization of Difluoroethenes Bearing Two Biaryl Groups

“…Cyclization precursors, symmetrically or unsymmetrically substituted 1,1-bis­(biaryl-2-yl)-2,2-difluoroethenes 3 , were readily prepared from 1,1,1-trifluoro-2-iodoethane ( 5 ) or 1,1-difluoroethylene ( 6 ), respectively, which are commercially available starting materials (Scheme ). The double Suzuki–Miyaura coupling between potassium (biaryl-2-yl)­trifluoroborates and 1,1-difluoro-2,2-diiodoethene ( 7 ), obtained by successive treatment of 5 with LDA and I 2 , gave symmetrical 1,1-bis­(biaryl-2-yl)-2,2-difluoroethenes 3a – d (Scheme i). In contrast, unsymmetrical 1,1-bis­(biaryl-2-yl)-2,2-difluoroethenes 3e – m were prepared via the Suzuki–Miyaura coupling between (biaryl-2-yl)­trifluoroborates and 1-(biphenyl-2-yl)-1-bromo-2,2-difluoroethene ( 8 ), which was obtained via the Negishi coupling of the 2,2-difluorovinylzinc–TMEDA complex derived from 6 and subsequent bromination of the intermediary difluoroalkene 9 (Scheme ii).…”