Solvent-dependent regio- and stereo-selective reactions of 3-formylchromones with 2-aminobenzothiazoles and transacetalization efficiency of the product 3-((benzo[]thiazol-2-ylimino)butyl)-4-chromen-4-one.

Using 2-propanol as the solvent, 3-formylchromones and 2-aminobenzothiaoles formed corresponding imines, while 1° and 2°-alcohols formed the corresponding 2-alkoxy-3-enamines with selectivity for the -isomer. Changing the substrates with similar molecules such as 3-formylchromone with quinoline-, quinolone- and indole-3-carbaldehydes sometimes resulted in the formation of the corresponding imines, whereas replacing 2-aminobenzothiazole with amides resulted in the formation of acetals. Considering the effect of the solvent, replacing alcohols with the aprotic solvents THF and CHCl resulted in the formation of imines and enamines, which are the characteristic reactions of 2-propanol and other 1° and 2°-alcohols, respectively.