Synthesis 2009(9): 1513-1519  
DOI: 10.1055/s-0029-1216633
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of 2-(Arylamino)ethanethiols via Lewis Acid Catalyzed Aminolysis of 2,2-Dimethylthiirane as Precursors of the 1,4-Benzothiazine Nucleus

Roberto Spogli, Stefano Sabatini*, Giuseppe Manfroni, Oriana Tabarrini, Violetta Cecchetti
Dipartimento di Chimica e Tecnologia del Farmaco, Università di Perugia, 1 Via del Liceo, 06123 Perugia, Italy
Fax: +39(75)5855115; e-Mail: [email protected];
Further Information

Publication History

Received 3 October 2008
Publication Date:
14 April 2009 (online)

Abstract

Ring opening of 2,2-dimethylthiirane by deactivated aromatic amines to afford 2-(arylamino)ethanethiols as 6-substituted 1,4-benzothiazine precursors, was investigated. The reaction takes place under mild conditions using copper(II) triflate or indium(III) triflate as catalysts. The regioselectivity of the addition depends on the catalysts and the substituents of the arylamines.

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10

The molecular weights for all the compounds 3 and 4 were confirmed by mass spectrometry. In particular for all the aminoethanethiols 3, the base peak corresponds to a loss of 75 amu (Me2CSH) from the molecular peak, and it correspond to a loss of 47 amu (CH2SH) for aminoethane-thiols 4. This behavior, first observed by Isaac9b and then by Usui,9c permitted an easy identification between those regioisomers by GC-MS analysis.