REACTION OF (3-FURYLMETHYL)COBALOXIME WITH DIENOPHILES - VARIABLE-MODE OF THE REACTION BY THE TYPE OF DIENOPHILES

(3-Furylmethyl)cobaloxime reacts with dienophiles in three reaction modes: (a) a 1,4-addition with N-phenylmaleimide and maleic anhydride, (b) a 1,4-cycloaddition and concomitant 1,3-migration of the cobaloxime moiety with dimethyl acetylenedicarboxylate, and (c) a formal aromatic substitution on the furan ring with active carbonyl compounds such as 2-oxomalonate, hexafluoroacetone, and 2-oxoaldehydes. The adducts from 2-aryl-2-oxoacetaldehyde easily loose the cobaloxime moiety on heating and give 2-(2-aryl-2-oxoacetyl)-3-methylfuran.