Synthese substituierter N‐Hydroxylactame, Lactame, Chinolin‐N‐oxide und Chinoline durch katalysierte Reduktive Cyclisierung von 2‐Nitrocinnamoyl‐Verbindungen mit Wasserstoff/Platinschwarz

Abstract

Synthesis of Substituted N‐Hydroxylactams, Lactams, Quinoline‐N‐oxides, and Quinolines by Catalyzed Reductive Cyclization of 2‐Nitrocinnamoyl Derivatives with Hydrogen/Platinum Black Substituted nitrobenzenes 1a–1m, consisting of two series of 6 analogous compounds, containing the structural unit of an α,β‐substituted 2‐nitrocinnamoyl group have been reductively cyclized by means of hydrogen in the presence of platinum black catalyst to form four types of heterocycles: N‐hydroxylactams 2a and b, lactams 3 and 4, quinoline‐N‐oxides 5a–d, and quinolines 6a and b. The type of substituents at the 2‐nitrocinnamoyl group is of significance for the type of heterocycle formed in this reaction. It is of special interest that by the use of the reduction system hydrogen/platinum black the probability to obtain N‐hydroxylactams or quinoline‐N‐oxides, which are difficult to obtain by alternative procedures, becomes much higher than by the use of many reducing agents acting noncatalytically.

ChemInform Abstract: Photocyclization Reactions. Part 8. Synthesis of 2‐Quinolone, Quinoline and Coumarin Derivatives Using trans‐cis Isomerization by Photoreaction.

“…H and13 C nmr spectra of 3d were identical with those of a commercially available sample. Recrystallization gave colorless crystals from ether, mp 84-85 °C (Commercially available sample, mp 84-85 °C); 1 H nmr (deuteriochloroform):…”

“…Ethyl trans-o-nitrocinnamate (1.00 g, 4.52 mmol) [13] and hydrazine monohaydrate (0.44 ml, 9.06 mmol) were dissolved in ethanol (100 ml). After 7% palladium-charcoal (0.10 g) was added, the solution was refluxed for 30 minutes.…”

“…The extract was washed, dried, and evaporated. The residue was chromatographed and eluted with benzene-acetone (1:1) to give trans-1b (0.49 g, 55%) as pale yellow crystals, mp 64-66 °C from ether-hexane; ir (potassium bromide): 3320 (NH 2 ), 3216 (NH 2 ), 1642 cm -1 (CON(CH 2 CH 3 ) 2 ); 1 H nmr (deuteriochloroform): δ 1.19 (t, J=7.0 Hz, 3H, CON(CH 2 CH 3 ) 2 ), 1.26 (t, J=7.0 Hz, 3H, CON(CH 2 CH 3 ) 2 ), 3.1-4.3 (broad s, 2H, NH 2 ), 3.46-3.50 (m, 4H, CON(CH 2 CH 3 ) 2 and CON(CH 2 CH 3 ) 2 ), 6.72-6.78 (m, 3H, Ar-H 2 and CH=CHCO), 7.15 (dd,J=7.5 and 7.5 Hz,1H,7.37 (d,J=7.5 Hz,1H,7.85 (d,J=15.5 Hz,1H,CH=CHCON); 13 C nmr (deuteriochloroform): δ 13.6 (q), 15.5 (q) Anal. Calcd.…”

“…δ 7.49 (dd, J=8.5 and 8.5 Hz, 1H, 3H,,7.75 (dd, J=8.5 and 8.5 Hz, 1H, 7.86 (d, J=8.5 Hz, 1H, Ar-H),7.90 (d, J=8.5 Hz, 1H, 3H, 8.25 (d, J=8.5 Hz, 1H, Ar-H);13 C nmr (deuteriochloroform): δ 119.0 (d), 126.3 (d), 127.2 (s), 127.4 (d), 127.6 (d), 128.8 (d), 129.3 (d), 129.7 (d), 136.8 (d), 139.6 (s), 148.2 (s), 157.3 (s). 2-Methylquinoline.…”

Preparation of Indoles from α-Aminonitriles: A Short Synthesis of FGIN-1-27

“…Esters and amides of 2-aminocinnamic acid can be easily obtained from commercially available 2-nitrocinnamic acid or via Heck reaction from 2-iodoaniline. [23][24][25] The latter procedure also permits the facile introduction of substituents to positions 4-7 of the indole skeleton. As an example, the 5-fluoro-substituted products 5h-j could be readily prepared from 4-fluoroaniline (Scheme 3).…”