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A new procedure for the cyclization of 2‐indole‐ and 3‐indolecarbohydrazones to 5 H ‐pyridazino[4,5‐ b ]indole derivatives
Author(s) -
Vega A. Monge,
Palop J. A.,
Martínez M. T.,
Alvarez E. Fernández
Publication year - 1980
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570170209
Subject(s) - chemistry , triethylamine , indole test , chloroform , hydrochloric acid , ethanol , medicinal chemistry , organic chemistry , proton nmr , nmr spectra database , spectral line , physics , astronomy
Abstract A new procedure for the cyclization of 2‐indolecarbohydrazones (5) to 1,2,3,4‐tetrahydro‐4‐oxo‐5 H ‐pyridazino[4,5‐ b ]indoles (6) and for the cyclization of 3‐indolecarbohydrazones (7) to 1‐oxo‐1,2,3,4‐tetrahydro‐5 H ‐pyridazino[4,5‐ b ]indoles (8 and 9) is described. The hydrazones (5 or 7) were treated with an acyl halide (acetyl or benzoyl chlorides) and triethylamine in ethyl acetate of chloroform as solvents to give the compounds 6 (20–70%) from the compounds 5 , and the compounds 8 (20–60%) from the compounds 7 . Through refluxing with ethanol‐hydrochloric acid the compounds 8a‐8f selectively separate the acetyl group on N 5 to give the respective compounds, 9a‐9f. The ir and 1 H‐nmr spectra of all the compounds 5, 6, 7, 8 and 9 and the uv, mass and 13 C‐nmr spectra of the compounds 7h, 7i, 8h and 8i are discussed.