SHORT COMMUNICATIONSWe previously described acylation with 5-arylfuran-2,3-diones of the β-CH group in the enamino tautomers of substituted 1-methyl-3,4-dihydroisoquinolines having no other functional groups. These reactions afforded (2Z,5Z)-1-aryl-3-hydroxy-5-[3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]pent-2-ene-1,4-diones [1,2]. In the present communication we report on the reaction of 5-arylfuran-2,3-diones with 1-methylidene-1,2,3,4-tetrahydroisoquinolines possessing an additional functional group at the exocyclic carbon atom attached to C 1 . 5-Arylfuran-2,3-diones Ia and Ib reacted with [3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]-acetamides IIa and IIb at a ratio of 1 : 1 on heating in boiling anhydrous benzene (reaction time 1-2 h). The progress of the reactions was monitored by thin-layer chromatography, and the products were the corresponding (3E,5Z)-5-(2-aryl-2-oxoethylidene)-3-[3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]pyrrolidine-2,4-diones IIIa and IIIb whose structure was determined by X-ray analysis.Presumably, the first reaction step is acylation of the β-CH group in the enamino fragment of isoquinolines IIa and IIb by the C 2 =O carbonyl carbon atom of 5-arylfuran-2,3-diones Ia and Ib. The subsequent opening of the furan ring at the O 1 -C 2 bond (as report-I, Ar = Ph (a), 4-MeC 6 H 4 (b); II, R = H (a), MeO (b); III, Ar = Ph, R = H (a), Ar = 4-MeC 6 H 4 , R = MeO (b).