New synthesis of 7-bromo-1, 3-dihydro-3-hydroxy-5-(2′-pyridyl)-2H-1,4-benzodiazepin-2-one

doi:10.1002/JHET.5570180112

Paper

New synthesis of 7-bromo-1, 3-dihydro-3-hydroxy-5-(2′-pyridyl)-2H-1,4-benzodiazepin-2-one

Published 1981 · T. Kovač, B. Belin, T. Fajdiga

Journal of Heterocyclic Chemistry

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6

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Abstract

A new synthesis of 7-bromo-1,3-dihydro-3-hydroxy-5-(2′-pyridyl)-2H-1,4-benzodiazepin-2-one (5) is described. Starting from bromazepam (3), C(3) acylation with lead tetraacetate/potassium iodide in acetic acid affords 4, while its mild hydrolysis according to our recently described method (5) gives 5. Improved hexamine cyclization of 1 into 3, via quaternary hexaminium salt 2, is discussed, and identification of the intermediates 7 and 8 is performed. Compound 5 undergoes on melting, or on brief heating in glacial acetic acid, the thermal rearrangement into quinazolin-2-aldehyde (13), the structure of which is confirmed by oxidation into the ester 14, which in turn was hydrolyzed to the acid 15. The same compound (5) rearranges on heating with manganese(III) acetate in acetic acid into the 3-amino-2-quinolone derivative 6. On heating in glacial acetic acid in the presence of lead tetraacetate/potassium iodide (or iodine), compound 4, in addition to giving the aldehyde 13, ester 14 and acid 15 rearrangement products, affords 1,2-dihydroquinazolin-2-carboxylic acid 16.

Study Snapshot

This new synthesis of 7-bromo-1,3-dihydro-3-hydroxy-5-(2′-pyridyl)-2H-1,4-benzodiazepin-2-one (5) offers a new route for the synthesis of related compounds.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

New synthesis of 7-bromo-1, 3-dihydro-3-hydroxy-5-(2′-pyridyl)-2H-1,4-benzodiazepin-2-one

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