Compounds of Formula 1 ##STR1## where the symbols have the meaning disclosed in the specification are prepared by reaction of a compound of Formula 2 ##STR2## with an organometal reagent R--M to provide a compound of Formula 3 ##STR3## that is reacted with the reagent X 3 --Y(R 2 )--A--B in the presence of a catalyst to provide the compounds of Formula 1.