WITTIG REAGENTS AND METHOD FOR PREPARING alpha , beta -UNSATURATED PHOSPHONATES

摘要

Wittig-type reagents and methods of preparation and use thereof for preparing alpha , beta -unsaturated phosphonate esters from aldehydes and ketones are disclosed. The Wittig-type reagents have formulae (I) and (II), wherein X represents triflate, halide, BF4, SbF6, or C1O4; R1 represents alkyl, aryl or arylalkyl; and R2 represents alkyl, aryl or arylalkyl, provided that R1 and R2 do not represent phenyl at the same time. The Wittig reagent diethyl phosphonomethylidenetriphenylphosphorane (1b) has been successfully synthesized for the first time via its phosphonium triflate salt (4a), by treating diethyl phosphonomethyltriflate with triphenylphosphine according to the disclosed method. The procedure has been applied to the synthesis of other new Wittig-type reagents such as phosphoranes and phosphonium salts. The new Wittig reagents thus synthesized were treated with various aldehydes and an activated ketone, affording the corresponding alpha , beta -unsaturated phosphonates, saturated phosphonates or phosphoric acids. Triphenylphosphorane (1b) and triphenylphosphonium (4a) led to both cis and trans isomers with the latter being predominant, while trans isomers were almost exclusively formed when tributyl reagents (1c and 4d) were used.