Highly selective cross-coupling reactions of aryl(halo)silanes with aryl halides: A general and practical route to functionalized biaryls
摘要:
The palladium catalyzed cross-coupling reaction of aryl halides with aryl(halo)silanes (halogen= F, Cl) gives good yields of unsymmetrical biaryls and p-terphenyls. The reaction takes place smoothly in N,N-dimethylformamide in the presence of an appropriate palladium catalyst and potassium fluoride. Since this reaction is tolerant of a variety of reactive functional groups, highly functionalized 4,4'-, 3,4'-, 2,4'- and even sterically crowded 2,2'-disubstituted biaryls can be obtained in moderate to high yields. The synthetic utility of the method has been demonstrated by its application to a short synthesis of liquid crystals. Mechanistic aspects of transmetalation of an aryl(fluoro)silicate intermediate with a palladium complex are discussed on the basis of the substituent effects on the rate of the cross-coupling reactions.
The palladium catalyzed cross-coupling reaction of aryl halides with aryl(halo)silanes (halogen= F, Cl) gives good yields of unsymmetrical biaryls and p-terphenyls. The reaction takes place smoothly in N,N-dimethylformamide in the presence of an appropriate palladium catalyst and potassium fluoride. Since this reaction is tolerant of a variety of reactive functional groups, highly functionalized 4,4'-, 3,4'-, 2,4'- and even sterically crowded 2,2'-disubstituted biaryls can be obtained in moderate to high yields. The synthetic utility of the method has been demonstrated by its application to a short synthesis of liquid crystals. Mechanistic aspects of transmetalation of an aryl(fluoro)silicate intermediate with a palladium complex are discussed on the basis of the substituent effects on the rate of the cross-coupling reactions.
Osman, Maged A., Molecular Crystals and Liquid Crystals (1969-1991), 1985, vol. 128, p. 45 - 64