Reaction of 2,3-dioxopyrrolo[2,1-a]isoquinolines with naphthalene-2,3-diamine

Abstract

We previously studied reactions of 2,3-dioxopyrrolo[2,1-a]isoquinolines with o-phenylenediamine [1, 2]. Reactions of these compounds with bulkier binucleophiles were not reported. While performing studies in this line, we found that dioxopyrrolo[2,1-a]isoquinoline I reacts with naphthalene-2,3-diamine on heating in boiling glacial acetic acid to produce fused hexacyclic system III. By reaction of naphthalene-2,3diamine with analogous tetracyclic compound II of the benzo[f]isoquinoline series we obtained heptacyclic structure IV. Compounds III and IV attract interest as new synthons, biologically active substances, and luminophors [3]. with 25% aqueous ammonia and water, dried, and recrystallized from isopropyl alcohol. Yield 2.31 g (66%), yellow crystals, mp 222–224°C. H NMR spectrum, δ, ppm: 1.92 s (6H, CH3), 3.13 s (2H, 6-H), 7.00 s (1H, 1-H), 7.21–8.58 m (10H, Harom). Mass spectrum, m/z (Irel, %): 349 (67) [M], 334 (45) [M – CH3], 319 (55) [M – 2CH3]. Found, %: C 82.43; H 5.41; N 12.12. C24H19N3. Calculated, %: C 82.49; H 5.48; N 12.03. M 349.43. 6,6-Dimethyl-5,6-dihydrobenzo[g]naphtho[1′,2′:7,8]indolizino[2,3-b]quinoxaline (IV) was synthesized in a similar way from 2.77 g (10 mmol) of compound II [4]. Yield 71%, yellow crystals, mp 268– 270°C. H NMR spectrum, δ, ppm: 2.00 s (6H, CH3), 3.60 s (2H, 6-H), 7.08 s (1H, 1-H), 7.16–8.66 m (12H, Harom). Mass spectrum, m/z (Irel, %): 399 (16) [M], 384 (8) [M – CH3], 369 (20) [M – 2CH3]. Found, %: C 84.12; H 5.23; N 10.63. C28H21N3. Calculated, %: C 84.18; H 5.30; N 10.52. M 339.49. The H NMR spectra were recorded on a Bruker300 spectrometer (300 MHz) from solutions in CDCl3 using HMDS as internal reference (δ 0.05 ppm). The mass spectra (electron impact, 70 eV) were obtained on a Finnigan MAT INCOS 50 instrument.