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

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.

Key words

Lewis acids - catalysis - 2,2-dimethylthiirane - 2-(aryl-amino)ethanethiols - aminolysis reaction - 1,4-benzothiazines

References

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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 Isaac^9b and then by Usui,^9c permitted an easy identification between those regioisomers by GC-MS analysis.