HIGHLY SELECTIVE CROSS-COUPLING REACTION OF ORGANOSILICON COMPOUNDS MEDIATED BY FLUORIDE-ION AND PD CATALYST

Highly selective cross-coupling reaction of organosilanes with organic halides and organic triflates promoted by palladium catalyst and fluoride ion is described. Organosilicon compounds like (E)- or (Z)-alkenyl, alkynyl, allyl, and arylsilanes smoothly react with alkenyl, allyl and aryl halides to give coupled products with high chemoselectivity and stereospecificity. Under similar conditions, silylation of alkenyl iodides by hexamethyldisilane and methylation of aryl iodides by (Et2N)3S+Me3SiF2- take place. The one-pot double cross-coupling of trimethylstannyl (trimethylsilyl) acetylene with two alkenyl iodides is achieved to afford isomerically pure dienynes. The crosscoupling of chiral 1-phenyl-1-trifluorosilylethane with aryl triflates occurrs stereo-specifically, providing optically active coupled products. The stereochemistry of the products is influenced decisively by reaction temperature and solvent used. A transition state model for the transmetallation step in catalytic cycle is proposed on the basis of substituent effect and stereochemical study of this reaction. © 1990, The Society of Synthetic Organic Chemistry, Japan. All rights reserved.