About the synthesis of [1,2]diazepinoindole derivatives from ethyl 2-(1-methylindole)acetate, 2-indole and 3-indoleacetohydrazones

• Published in: Journal of heterocyclic chemistry Vol. 22; no. 5; pp. 1445 - 1451
• Main Authors: Monge, A., Palop, J. A., Goñí, T., Martínez, A., Fernández-Alvarez, E.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley-Blackwell 01-09-1985; Wiley‐Blackwell; HeteroCorporation
• Subjects: Chemistry; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Organic chemistry; Preparations and properties; Bicyclic compound; Aromatic compound; Infrared spectrum; Tricyclic compound; NMR spectrum; Nitrogen heterocycle
• ISSN: 0022-152X; 1943-5193
• DOI: 10.1002/jhet.5570220565

The Vilsmeier‐Haack reaction with ethyl 2‐(1‐methylindole)acetate and N,N‐Dimethylamides/phosphorus oxychloride gave (65–85%) of ethyl 2‐(3‐acyl‐1‐methylindole)acetates 2, which when boiled with hydrazine yielded about 90% of 4,5‐dihydro‐6‐methyl‐4‐oxo‐3H[1,2]diazepino[5,6‐b]indoles 3. The attempted cyclization of 2‐(1‐methylindole)acetohydrazones 6 with acyl (acetyl and benzoyl) chlorides/triethylamine, to [1,2]diazepino[5,6‐b]indole derivatives was fruitless and the bis(acyl)hydrazones 9 were obtained. Several transformations of 9 are reported. Similarly, the attempted cyclization of 3‐indoleacetohydrazones 14 with acetyl chloride/triethylamine to [1,2]diazepino[4,5‐b]indole derivatives was also fruitless and the bis(acyl)hydrazones 16 were again obtained.