Studies on chalcogen-containing heterocycles. Part 38: Regio- and stereoselective tandem addition–iodocyclization of 2-ethynylphenyl isothiocyanates with N- and O-nucleophiles affording 4-(iodoalkylidene)benzo[d][1,3]thiazines
摘要:
The treatment of the o-ethynylphenyl isothiocyanates with primary and secondary amines in 1,2-DCE, followed by the addition of 12 and then heating resulted in the regio- and stereoselective tandem addition-iodocyclization to give the (4E)-2-amino-4-(1-iodomethylidene)benzo[d][1,3]thiazine derivatives as the sole product in high yields via the 6-exo-dig mode cyclization. The 2-alkoxy-1,3-benzothiazines were similarly produced from the o-ethynylphenyl isothiocyanates and the corresponding sodium alkoxides. (C) 2013 Elsevier Ltd. All rights reserved.
三氟甲磺酸银促进了N-(2-乙炔基苯基)硫脲的6-exo-dig模式环化反应,这是很容易从邻乙炔基苯基异硫氰酸酯和伯胺获得的,从而提供了2-亚氨基-4-亚甲基-1 H作为唯一产品的-苯并[ d ] [1,3]噻嗪具有极好的收率。仲胺与邻乙炔基苯基异硫氰酸酯在相同条件下反应,生成6-exo和5-endo-dig模式环化产物。