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5,6‐Dihydro‐4 H ‐pyrrolo[1,2‐ a ][1,4]benzodiazepine‐4,4‐diacetic acid diethyl ester, an useful synthon for the synthesis of new polycyclic nitrogen systems of pharmacological interest
Author(s) -
Massa Silvio,
Mai Antonello,
Santo Roberto Di,
Artico Marino
Publication year - 1993
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.5570300409
Subject(s) - chemistry , synthon , piperidine , benzodiazepine , sodium ethoxide , medicinal chemistry , stereochemistry , pyrrole , sodium hydride , organic chemistry , biochemistry , receptor , ethanol
This report describes the synthesis of derivatives of two nitrogen tetracyclic ring systems, respectively 9 H ,11 H ‐pyrimido[4,3‐ c ]pyrrolo[1,2‐ a ][1,4]benzodiazepine and spiro[piperidine‐4,4′‐[4 H ]pyrrolo[1,2‐ a ][1,4]‐benzodiazepine], by the use of the diethyl ester of 5,6‐dihydro‐4 H ‐pyrrolo[1,2‐ a ][1,4]benzodiazepine‐4,4‐diacetic acid as a synthon. This compound was obtained by condensation of 1‐(2‐aminomethylphenyl)‐1 H ‐pyrrole with diethyl 1,3‐acetonedicarboxylate in acid medium. Pyrimidopyrrolobenzodiazepine derivatives were obtained by treating either the pyrrolobenzodiazepine 4,4‐diacetate or the related 4‐methyl‐4‐acetate with phenylisocyanate in boiling diethyl ether in the presence of sodium metal. The structure of 12,13‐dihydro‐11,13‐dioxo‐12‐phenyl‐9 H ,11 H ‐pyrimido[4,3‐ c ]pyrrolo[1,2‐ a ][1,4]benzodiazepine, a product formed by loss of an acetate unit when 5,6‐dihydro‐4 H ‐pyrrolo[1,2‐ a ][1,4]benzodiazepine‐4,4‐diacetate, sodium metal and phenyl‐isocyanate reacted in boiling xylene, was proved by catalytic reduction to 11,13‐dioxo‐12‐phenyl‐12,13,14,14a‐tetrahydro‐9 H ,11 H ‐pyrimido[4,3‐ c ]pyrrolo[1,2‐ a ][1,4]benzodiazepine, which was synthesized by unambiguous pathway via 5,6‐dihydro‐4 H ‐pyrrolo[1,2‐ a ][1,4]benzodiazepine‐4‐acetate. The 2,6‐dioxospiro[piperidine‐4,4′‐[4 H ]pyrrolo[1,2‐ a ][1,4]benzodiazepine] derivatives were synthesized from the N ‐BOC derivative of 5,6‐dihydro‐4 H ‐pyrrolo[1,2‐ a ][1,4]benzodiazepine‐4,4‐diacetic acid diethyl ester, by hydrolysis followed by treatment with 2 equivalents of 1,1′‐carbonyldiimidazole (CDI) and then with aniline or benzylamine. Removal of BOC from the N ‐phenyl‐2,6‐dioxopiperidine derivative was obtained by heating the related spiroderivative in toluene in the presence of p ‐toluenesulphonic acid. Similar reaction failed when the N ‐benzyl‐2,6‐dioxopiperidine analog was used as substrate.