A green approach towards the on-water synthesis of multifunctional 3-amino/hydroxy thieno[3,2-]pyrans.

An efficient, one-pot, and green synthetic strategy was established for 3-amino/hydroxy thieno[3,2-]pyrans in water through a reaction of 6-aryl-4-(methylthio)-2-oxo-2-pyran-3-carbonitriles/carboxylates with methyl thioglycolate, yielding excellent results (65-95%). The present approach was also employed to synthesize benzo[]thieno[3,2-]chromene-2-carboxylate derivatives in good yield. This efficient method eliminated the need for tedious purification steps, and the products were purified by simply washing the crude material with lukewarm water. Furthermore, the reaction medium was reusable and could be repeated up to six cycles, producing the desired product with only minimal loss, although the reaction time increased with each cycle. All the synthesized compounds were characterized by spectroscopic analysis, and the structure of one compound was confirmed by single-crystal X-ray analysis.