Ahmed, Owais published the artcileSolvent-dependent regio- and stereo-selective reactions of 3-formylchromones with 2-aminobenzothiazoles and transacetalization efficiency of the product 3-((benzo[d]thiazol-2-ylimino)butyl)-4H-chromen-4-one, Formula: C7H5ClN2S, the publication is RSC Advances (2019), 9(36), 20573-20581, database is CAplus and MEDLINE.
Using 2-propanol as the solvent, 3-formylchromones I (R = H, 6-Cl, 6-Br, 6-OH, 6-Cl-8-Br) and 2-aminobenzothiazoles II [R1 = 4-Cl, 6-Br, 4,6-(F2), etc.] formed corresponding imines, (Z)-III while 1° and 2°-alcs. R2OH [R2 = CH3, CH(CH3)2, cyclohexyl, etc.] formed the corresponding 2-alkoxy-3-enamines IV with selectivity for the Z-isomer. Changing the substrates with similar mols. such as 3-formylchromone I with quinoline-, quinolone- and indole-3-carbaldehydes, e.g., 1,4-dihydro-4-oxoquinoline-3-carbaldehyde sometimes resulted in the formation of the corresponding imines, e.g., 3-((benzo[d]thiazol-2-ylimino)methyl)quinolin-4(1H)-one, whereas replacing 2-aminobenzothiazole with amides R3C(O)NH2 (R3 = H, Me, Ph) resulted in the formation of acetals V. Considering the effect of the solvent, replacing alcs. with the aprotic solvents THF and CH2Cl2 resulted in the formation of imines and enamines, which are the characteristic reactions of 2-propanol and other 1° and 2°-alcs., resp. 2-Alkoxy-3-enamines were found to undergo transacetalization with both short and long chain alcs. The novelty of these reactions is that they did not require an external catalyst, all the reactions were performed at the same temperature, and purification was achieved by filtration. The transacetalization has been performed as a new concept, which has not been reported to date. In contrast, other similar reactions, such as transalkoxylation, transalkylation, and transetherification, are performed on a com. scale using expensive catalysts such as Otera’s catalyst. The highly sensitive nature of 3-formylchromones towards variations in the substrates and solvents to form different products and the reason behind the selective formation of the Z-isomer of 2-alkoxy-3-enamines and its transacetalization efficiency need further studies to understand the reaction mechanism and possibly other factors such as solvent effects.
RSC Advances published new progress about 95-24-9. 95-24-9 belongs to thiazole, auxiliary class Organic Pigment, name is 6-Chlorobenzothiazol-2-ylamine, and the molecular formula is C7H5ClN2S, Formula: C7H5ClN2S.
Referemce:
https://pubchem.ncbi.nlm.nih.gov/compound/thiazole,
Thiazole | chemical compound | Britannica