Synthesis of benzodiazepines catalyzed by chitosan functionalized by triacid imide as a superior catalyst
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Synthesis of benzodiazepines catalyzed by chitosan functionalized by triacid imide as a superior catalyst Mozhgan Esfandiari1 · Ali Kareem Abbas2 · Mohammad Reza Vakili3 · Hossein Shahbazi‑Alavi4 · Javad Safaei‑Ghomi5 Received: 31 July 2020 / Accepted: 18 September 2020 © Springer Nature B.V. 2020
Abstract Chitosan functionalized by triacid imide has been applied as an effective catalyst for the synthesis of benzodiazepines by one-pot reactions of 1,2-phenylenediamine with dimedone and aryl aldehydes or isocyanides and Meldrum’s acid. Chitosan functionalized by triacid imide was confirmed by FT-IR (infrared spectroscopy), XRD (X-ray diffraction), DSC (differential scanning calorimetry) and TGA (thermogravimetric analysis). To investigate the scope and limitation of this reaction, different aryl aldehydes and isocyanides were used as substrates. Good yields in short reaction times, experimental simplicity, extensive range of products, retrieval of the catalyst and low catalyst loading are some of the substantial aspects of this method. Graphic abstract = chitosan functionalized by triacid imide
H N N H
O
O
O NH-R2
R2
N C 3'
O O
O
O
2'
NH2
O
NH2
CH2Cl2, rt
5a-e
O
2
O
Ar
3
EtOH, rt
1
O
H N N H
Ar
4a-e
Keywords Benzodiazepines · One-pot · Chitosan · Triacid imide
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1116 4-020-04281-x) contains supplementary material, which is available to authorized users. * Hossein Shahbazi‑Alavi [email protected] Extended author information available on the last page of the article
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Introduction Benzodiazepines display anti-bacterial [1], anti-tumor [2], anti-anxiety [3], antiAIDS [4] and anti-hepatic B virus [5] activities. The discovery of impressive methods for the preparation of benzodiazepines is a serious challenge. A number of ways have been improved for the synthesis of diazepines using mercury(II) trifluoromethanesulfonate [6], organic acid [7], ytterbium(III) trifluoromethanesulfonate [8], ceric ammonium nitrate [9] and scandium(III) trifluoromethanesulfonate [10]. Each of these procedures may have its own advantages but also suffer from such apparent drawbacks as prolonged reaction times, complicated work-up, low-yield or hazardous reaction conditions. The potential of chitosan-based structures to form open network has provided their use not only as macrochelating ligands, but also as a direct organocatalyst [11]. The chitosan can be applied as a support for the synthesis of new catalysts in the form of flakes, colloids, fibers, gel or functionalized on inorganic supports (alumina, titania, silica or other metal oxides) [12, 13]. Chitosan functionalized with sulfonic acid was utilized as a superior catalyst in the esterification of fatty acids with alcohol [14]. Amino and hydroxyl groups in chitosan make it suitable as an effective catalyst [15, 16]. Chitosan is a biopolymer that can be utilized as green catalyst in many reactions [17, 18]
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