| abstract |
Provided is a use as a coupling agent for condensation reactions of a compound of formula (I): wherein each of R1, R2, and R3 is independently H, hydrocarbyl, or hydrocarbyloxy, provided chat not more than one of R1 R2, and R3 is H; and at least one of Y1 and Y2 is an electron-withdrawing group and the other, if not an electron-withdrawing group, is H or a group that has no electron-donating properties, with the proviso that when one of Y1 and Y2 is H, the other is not -CN. Some of the compounds of formula (I) are novel, and methods of their preparation are also provided. |