Synthesis of 2-amino-4H-thiazolo[5,4-b]indole and characterization of its colored conversion products with protein tyrosine phosphatase inhibitory activity

In DMSO-solution 2-amino-4H-thiazolo[5,4-b]indole is converted into a compl ex mixture of colored products. The three major conversion end-products, of which two are inhibitors of protein tyrosine phosphatases (PTPs), were iso lated by chromatographic methods and their structures characterized by spec troscopic analysis, including NMR and M:S combined with computer assisted s tructure elucidation, and, finally, confirmed by independent chemical synth esis. Synthesis of 2-amino-4H-thiazolo[5,4-b]indole as well as its N-acetyl derivatives prepared from either oxindole or 2-bromo-1-(2-nitro-phenyl)eth anone is described.