NEW MATERIAL:The Michael addition product of formula I (R is aliphatic or aromatic hydrocarbon group; X is group originated from the receptor for Michael addition reaction).

EXAMPLE: The Michael addition product of methyl monofluoromalonate to ethyl vinyl ketone.

USE: Synthesis of fluorine-containing cyclic β-diketone by intramolecular Claisen condensation.

PROCESS: The addition compound of formula I can be prepared by (1) introducing hexafluoropropene into dioxane containing ammonia, (2) adding an alcohol (ROH) solution of an alkoxide (RO-) to the produced 2,3,3,3-tetrafluoropropionitrile to obtain the compound of formula II, (3) reacting the compound with a mineral acid (e.g. sulfuric acid), (4) adding a catalytic amount of a base (such as KF) to the resultant monofluoromalonic acid ester of formula III and stirring the mixture to generate the carbanion of formula IV, and (5) adding the receptor for the Michael addition reaction to the carbanion under ice cooling to effect the conversion of the ion to the addition compound of formula I .