Synthesis
DOI: 10.1055/s-0036-1590866
paper
© Georg Thieme Verlag Stuttgart · New York

5,6,7,8-Tetrahydronaphthalen-1-amine as Precursor for Thiazolidi­nones and Benzothiazepinones: Synthesis and Atropisomeric Relationship

Bruna B. Drawanza, Georgia C. Zimmerb, Leticia V. Rodriguesb, Andressa B. Nörnberga, Manfredo Hörnerc, Clarissa P. Frizzob, Wilson Cunico*a
  • aLaQuiABio, Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas, Campus Universitário s/no, 96010-900, Pelotas, RS, Brazil   Email: wjcunico@yahoo.com.br
  • bNUQUIMHE, Departamento de Química, Universidade Federal de Santa Maria, Av. Roraima nº 1000, Cidade Universitária, 97105-900,Santa Maria, RS, Brazil
  • cNITRICO, Departamento de Química, Universidade Federal de Santa Maria, Av. Roraima nº 1000, Cidade Universitária, 97105-900,Santa Maria, RS, Brazil
CNPq (307330/2012-5).
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Publication History

Received: 09 June 2017

Accepted after revision: 13 July 2017

Publication Date:
10 August 2017 (eFirst)

Abstract

The one-pot reaction of 5,6,7,8-tetrahydronaphthalen-1-amine, mercaptoacetic acid, and arenealdehydes having strong and weak electron-withdrawing groups gave the corresponding 1,3-thiazolidin-4-ones (47–70%). When arenealdehydes bearing strong and weak electron-donating groups were used as precursors, the 1,4-benzothiazepin-2-ones were obtained (30–72%) by p-TsOH catalysis. All compounds are unknown and were characterized by GC-MS and NMR techniques, and available crystals by X-ray diffraction studies. The atropisomerism phenomenon was observed in several 1,3-thiazolidin-4-ones as confirmed by VTNMR method. The Tc was established as 332 K and the energy required for the interconversion of one atrop­isomer into another is around 16.8 kcal·mol–1. Chemical quantum calculation and NOESY displayed that more stable isomer has the tetrahydro­naphthalene portion below the five-ring plane. Only a small difference between isomers (–0.21 to –0.84 kcal·mol–1) was observed by calculated energy.

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