A Facile Approach for the Synthesis of Benzothiazole from N-Protected Amino Acids

Abstract

Benzothiazole is gaining importance as a versatile nucleus in the field of Medicinal and Pharmaceutical Chemistry. The advancement in neuro imaging is in rapid progress and benzothiazoles are good imaging agents. Pittsburg compound, a benzothiazole derivative is used as imaging amyloid plaques in Alzheimer’s disease. Large numbers of methods are reported in literature for benzothiazole synthesis, however, many of them suffer from limitations such as low yield, metal catalyst, expensive reagents, toxic solvents, high temperature, long reaction times and harsh reaction conditions. In present research work, benzothiazole derivatives are prepared from N-protected amino acids and 2-aminothiopenol using molecular iodine as a mild Lewis acid catalyst. Six different α-amino acids were taken that were benzoyl protected and then Boc protected to prevent side reaction.. Twelve benzothiazoles were synthesized from benzoyl and Boc protected amino acids. Yields were compared for benzoyl and Boc protected benzothiazoles and it was found that Boc protected benzothiazoles provided better yield in these reaction conditions. The synthesized compounds were characterized by physical and spectroscopic techniques like FTIR and GCMS.