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Issue 108, 2016
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Regioselective “hydroamination” of alk-3-ynones with non-symmetrical o-phenylenediamines. Synthesis of diversely substituted 3H-1,5-benzodiazepines via (Z)-3-amino-2-alkenones

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Abstract

The reaction of alk-3-yn-1-ones (a bifunctional reagent) with o-phenylenediamines provides an effective synthetic method with high atom economy for the preparation of diversely substituted 1,5-3H-benzodiazepines. The reaction initially leads to the formation of conjugated enaminones (3-amino-2-alkenones, 51–99%), at room temperature, which constitutes a formal non-catalyzed hydroamination of the non-conjugated alkyne. Non-symmetrical o-phenylenediamines react in a regioselective fashion with respect to amino groups. Both the direct microwave-accelerated reaction of o-phenylenediamines with alkynones in ethanol and the intramolecular cyclization of intermediate enaminones in ethanol/acetic acid lead to substituted 1,5-benzodiazepines with good yields (39–92 and 26–99%). The regio- and stereochemical outcomes of these processes are confirmed by the X-ray structure determination of (Z)-3-[(2-amino-4-methylanilino)-4-(4-methylphenyl)-1-phenylbut-2-en-1-one], 4-[(4-methylphenyl)methyl]-7-nitro-2-phenyl-3H-1,5-benzodiazepine and 6,8-dimethyl-4-(4-methylbenzyl)-2-phenyl-3H-benzo[b][1,5]diazepine.

Graphical abstract: Regioselective “hydroamination” of alk-3-ynones with non-symmetrical o-phenylenediamines. Synthesis of diversely substituted 3H-1,5-benzodiazepines via (Z)-3-amino-2-alkenones

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Article information


Submitted
29 Sep 2016
Accepted
21 Oct 2016
First published
10 Nov 2016

RSC Adv., 2016,6, 107081-107093
Article type
Paper

Regioselective “hydroamination” of alk-3-ynones with non-symmetrical o-phenylenediamines. Synthesis of diversely substituted 3H-1,5-benzodiazepines via (Z)-3-amino-2-alkenones

J. Young, C. Schäfer, A. Solan, A. Baldrica, M. Belcher, B. Nişanci, K. A. Wheeler, E. R. Trivedi, B. Török and R. Dembinski, RSC Adv., 2016, 6, 107081
DOI: 10.1039/C6RA24291J

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