Pyrrolobenzodiazepines and related systems. 2. Synthesis and biological properties of isonoraptazepine derivatives

1,4-Diazepines: A Review on Synthesis, Reactions and Biological Significance

Background:

1,4-Diazepines are two nitrogen containing seven membered heterocyclic compounds and associated with a wide range of biological activities. Due to its medicinal importance, scientists are actively involved in the synthesis, reactions and biological evaluation of 1,4-diazepines since number of decades.

Objective:

The primary purpose of this review is to discuss the synthetic schemes and reactivity of 1,4- diazepines. This article also describes biological aspects of 1,4-diazepine derivatives, that can be usefully exploited for the pharmaceutical sector.

Conclusion:

This review summarizes the abundant literature on synthetic routes, chemical reactions and biological attributes of 1,4-diazepine derivatives. We concluded that 1,4-diazepines have significant importance due to their biological activities like antipsychotic, anxiolytic, anthelmintic, anticonvulsant, antibacterial, antifungal and anticancer. 1,4-diazepine derivatives with significant biological activities could be explored for potential use in the pharmaceutical industries.

An Update on the Synthesis of Pyrrolo[1,4]benzodiazepines

Pyrrolo[1,4]benzodiazepines are tricyclic compounds that are considered “privileged structures” since they possess a wide range of biological activities. The first encounter with these molecules was the isolation of anthramycin from cultures of Streptomyces, followed by determination of the X-ray crystal structure of the molecule and a study of its interaction with DNA. This opened up an intensive synthetic and biological study of the pyrrolo[2,1-c][1,4]benzodiazepines that has culminated in the development of the dimer SJG-136, at present in Phase II clinical trials. The synthetic efforts have brought to light some new synthetic methodology, while the contemporary work is focused on building trimeric pyrrolo[2,1-c][1,4]benzodiazepines linked together by various heterocyclic and aliphatic chains. It is the broad spectrum of biological activities of pyrrolo[1,2-a][1,4]benzodiazepines that has maintained the interest of researchers to date whereas several derivatives of the even less studied pyrrolo[1,2-d][1,4]benzodiazepines were found to be potent non-nucleoside HIV-1 reverse transcriptase inhibitors. The present review is an update on the synthesis of pyrrolo[2,1-c][1,4]benzodiazepines since the last major review of 2011, while the overview of the synthesis of the other two tricyclic isomers is comprehensive.

Iridium catalyzed asymmetric hydrogenation of cyclic imines of benzodiazepinones and benzodiazepines

Highly enantioselective Ir-catalyzed hydrogenation of seven-membered cyclic imines of benzodiazepinones and benzodiazepines was achieved with up to 96% ee. This method provides a direct access to synthesize a range of chiral cyclic amines existing in numerous important natural products and clinical drugs.

1,4-Diazepinone and Pyrrolodiazepinone Syntheses via Homoallylic Ketones from Cascade Addition of Vinyl Grignard Reagent to α-Aminoacyl-β-amino Esters

[reaction: see text] 1,4-Diazepinones 5 and pyrrolodiazepinones 8 and 9 were synthesized from common homoallylic ketone precursors 4 prepared by copper-catalyzed cascade addition of a vinyl Grignard reagent to alpha-aminoacyl beta-amino esters 3. Nitrogen deprotection and intramolecular reductive amination yielded 1,4-diazepinones 5. Olefin oxidation, Boc removal, and intramolecular Paal-Knorr condensation gave pyrrolodiazepinones 8 and 9. X-ray structures of diazepinones 5c and 5d depicted dihedral angles about the alpha-amino acid moiety similar to those of the central residue in an ideal reverse gamma-turn.

Synthesis and biological evaluation of enantiomerically pure pyrrolyl-oxazolidinones as a new class of potent and selective monoamine oxidase type A inhibitors

Due to the key role played by monoamine oxidases (MAOs) in the metabolism of neurotransmitters, MAO inhibitors (MAOIs) represent an useful tool for the treatment of several neurological diseases. Among selective MAOIs, MAO-A inhibitors (e.g. clorgyline) are used as antidepressant and antianxiety drugs and are claimed to protect neuronal cells against apoptosis, and selective MAO-B inhibitors (e.g. L-deprenyl) can be used in the treatment of Parkinson's disease either alone or in combination with L-DOPA. However, they engender covalent bonds with the active site of the enzyme and induce irreversible inhibition; moreover, they tend to lose their initial selectivity at high dosages or with repeated administrations. Phenyloxazolidinones belong to third-generation-MAOIs, characterized by a selective and reversible inhibition of the enzyme. Among these molecules, the most representative are toloxatone and befloxatone, two selective and reversible MAO-A inhibitors used in therapy as antidepressant drugs. Going on our searches on CNS potentially active compounds containing a pyrrole moiety we prepared 3-(1H-pyrrol-1-yl)-2-oxazolidinones (1) and isomeric 3-(1H-pyrrol-2-and -3-yl)-2-oxazolidinones (2 and 3) as anti-MAO agents. Such derivatives resulted selective and reversible MAO-A inhibitors. The most potent compound is (R)-5-methoxymethyl-3-(1H-pyrrol-1-yl)-2-oxazolidinone (1b), endowed with very high potency (K(iMAO-A) = 4.9 nM) and A-selectivity (A-selectivity = 10,200, about 116-fold greater than that of befloxatone).

3-(1H-Pyrrol-1-yl)-2-oxazolidinones as reversible, highly potent, and selective inhibitors of monoamine oxidase type A

3-(1H-Pyrrol-1-yl)-2-oxazolidinones 1aminus signi have been synthesized as pyrrole analogues of toloxatone (Humoryl), an antidepressant agent belonging to the 3-phenyl-2-oxazolidinone class, and their monoamine oxidase (MAO) type A and B inhibitory activities have been evaluated. The majority of 1aminus signi showed inhibitory activity against the A isoform of the enzyme higher than that exerted against the MAO-B, the sole exception being the (S)-5-aminomethylderivative 1d. (R)-5-Methoxymethyl-3-(1H-pyrrol-1-yl)-2-oxazolidinone 1b, the most potent among test derivatives, was 78-fold more potent than toloxatone.