Direct heterocyclization of tetrahydroisoquinolin-1-ylideneacetic acids by the action of 5-arylfuran-2,3-diones

Abstract

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).

Five-membered 2,3-dioxo heterocycles: LXIX. Direct heterocyclization of [3,4-dihydroisoquinolin-1(2H)-ylidene]-acetamides with 5-arylfuran-2,3-diones. Crystalline and molecular structure of (3E,5Z)-3-[3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]-5-(2-oxo-2-phenylethylidene)pyrrolidine-2,4-dione

“…The crystalline and molecular structures of one of the products were determined by X-ray analysis.* For communication LXVIII, see [1].We previously described acylation of substituted 1-methyl-3,4-dihydroisoquinolines at the β-CH group of enamino tautomer with 5-arylfuran-2,3-diones, which led to the formation of (2Z,5Z)-1-aryl-3-hydroxy-5-[3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]pent-2-ene-1,4-diones whose structure was proved by X-ray analysis [2]. In the present work we examined reactions of 5-arylfuran-2,3-diones with substituted [3,4-dihydroisoquinolin-1(2H)-ylidene]acetamides.…”

Five-membered 2,3-dioxoheterocycles: LXVII. Pyrroledione-pyrroledion recyclization of isopropyl 2-(1-aryl-4,5-dioxo-2-phenyl-4,5-dihydro-1H-pyrrol-3-yl)-2-oxoacetates under the action of arylamines. Crystal and molecular structure of (z)-isopropyl 2-hydroxy-4,5-dioxo-1-phenyl-3-[phenyl(phenylamino)-methylene]pyrrolidine-2-carboxylate

“…In the 1 H NMR spectra of compounds IIIa-IIIj alongside the signals of the protons of aromatic rings and groups attached thereto appear two doublets of methyl *For Communication LXVI, see [1].…”

“…In the 1 H NMR spectra of compounds IIIa-IIIj alongside the signals of the protons of aromatic rings and groups attached thereto appear two doublets of methyl *For Communication LXVI, see [1]. groups of the isopropoxycarbonyl substituent at 0.73-0.79 and 0.82-0.85 ppm, a multiplet of the methine proton from the same moiety in the region 4.32-4.34 ppm, and abroadened singlet of the NH group proton (12.62-12.68 ppm).…”

“…1 H and 13 C NMR spectra were registered on a spectrometer Bruker AM-400 (operating frequency 400 MHz) in DMSO-d 6 , internal reference TMS. The homogeneity of compounds synthesized was proved by TLC on Silufol plates, eluates benzene-ethyl acetate, 5 : 1, ethyl acetate.…”

Five-membered 2,3-dioxo heterocycles: LXVI. Reactions of (2Z,5Z)-1-aryl-3-hydroxy-5-[3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]pent-2-ene-1,4-diones with o-phenylenediamine and hydrazine. Crystalline and molecular structure of 2-{(Z)-8,8-dimethyl-2,3,8,9-tetrahydro[1,4]dioxino[2,3-g]isoquinolin-6(7H)-ylidene}-1-(3-phenyl-1H-pyrazol-5-yl)ethanone

“…The products were the corresponding (2Z,5Z)-1-aryl-3-hydroxy-5-[3,3-dialkyl-3,4-dihydroisoquinolin-1(2H)-ylidene]-pent-2-ene-1,4-diones I whose structure was proved by X-ray analysis [2]. These compounds were formerly assigned the structure of NH-acylation products of tautomeric N-aroylpyruvoyl-3,3-dimethyl-1,2,3,4-tetrahydro-2-methylideneisoquinolines [3], taking into account mainly easy elimination of isoquinoline by the action of o-phenylenediamine, which is typical of N-aroylpyruvoylamines [4].…”