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Synlett 2013; 24(19): 2601-2605
DOI: 10.1055/s-0033-1338984
letter
© Georg Thieme Verlag Stuttgart · New York

Bromodimethylsulfonium Bromide (BDMS)-Catalyzed Synthesis of 1,5-Benzodiazepines Using a Multi-Component Reaction Strategy

Satavisha Sarkar
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India   Fax: +91(361)2582349   Email: atk@iitg.ernet.in
,
Jugal Kishore Rai Deka
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India   Fax: +91(361)2582349   Email: atk@iitg.ernet.in
,
Jagadish P. Hazra
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India   Fax: +91(361)2582349   Email: atk@iitg.ernet.in
,
Abu T. Khan*
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India   Fax: +91(361)2582349   Email: atk@iitg.ernet.in
› Author Affiliations
Further Information

Publication History

Received: 14 August 2013

Accepted after revision: 08 September 2013

Publication Date:
14 October 2013 (online)

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This work is dedicated to the late Dr. Uttara Debi who was compassionate and amicable in nature.

Abstract

A new approach for the synthesis of multi-functionalized 1,5-benzodiazepines is developed starting from o-phenylenediamines, β-keto esters and aromatic aldehydes utilizing a one-pot, three-component strategy employing bromodimethylsulfonium bromide as the catalyst. The simple reaction procedure, good yields, mild reaction conditions and applicability to a wide range of substrates are some of the salient features of this protocol.

Key words

multi-component reactions - 1,5-benzodiazepines - o-phenylenediamines - bromodimethylsulfonium bromide

Supporting Information

    for this article is available online at http://www.thieme-connect.com/ejournals/toc/synlett.
  • Supporting Information
 

  • References and Notes

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  • 18 1,5-Benzodiazepines; General Procedure In an oven-dried 25 mL round-bottomed flask was added the requisite o-phenylenediamine (1.0 mmol) and β-keto ester (1.0 mmol) in DCE (3 mL). Next, bromodimethylsulfonium bromide (10 mol%) was added and the mixture was stirred at r.t. After 15 min, the aromatic aldehyde (1.0 mmol) was added and the mixture was heated at 55 °C for the appropriate amount of time. Following completion (TLC), the solvent was removed on a rotary evaporator. The residue was extracted with CH2Cl2 (2 × 10 mL), washed with H2O (10 mL) and dried over anhydrous Na2SO4. The solution was filtered, concentrated in vacuo and the residue purified by column chromatography (EtOAc–hexane, 5:95) to provide the 1,5-diazepine product. (Z)-Ethyl 2-(4-Phenyl-4,5-dihydro-1H-benzo[b][1,4]-diazepin-2(3H)-ylidene)acetate (4a) Yield: 0.213 g (75%); yellow solid; mp 73–77 °C. IR (KBr): 1158, 1455, 1618, 1637, 2923, 3415, 3467 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.28 (t, J = 7.2 Hz, 3 H, -CH3), 2.54 (dd, J = 14, 4.4 Hz, 1 H, -CH2), 2.70 (dd, J = 14, 9.2 Hz, 1 H, -CH2), 3.7 (br s, 1H, -NH), 4.1–4.2 (m, 2 H, -OCH2), 4.61 (s, 1 H, =CH), 4.85 (dd, J = 9.2, 4 Hz, 1 H, -CH), 6.76–6.79 (m, 1 H, Ar-H), 6.85–6.94 (m, 1 H, Ar-H), 6.96–7.05 (m, 2 H, Ar-H), 7.28–7.32 (m, 1 H, Ar-H), 7.32–7.39 (m, 4 H, Ar-H), 10.24 (s, 1 H, -NH). 13C NMR (100 MHz, CDCl3): δ = 14.75, 40.52, 59.05, 65.33, 82.42, 121.01, 121.80, 122.74, 125.19, 126.29 (2 C), 128.18, 129.03 (2 C), 130.11, 138.11, 145.07, 158.83, 170.52.HRMS (ESI): m/z [M + H]+ calcd for C19H20N2O2: 309.1598; found: 309.1594. Anal. Calcd for C19H20N2O2: C, 74.00; H, 6.54; N, 9.08. Found: C, 74.06; H, 6.59; N, 9.02.