Regiospecific Bi‐Catalysed Domino C‐N/C‐S Bonds Formation: Synthesis of 1,4‐Thiazines/1,4‐Thiomorpholines

Abstract

A domino Bi‐catalysed C−N/C−S bond formation of N‐sulfonylaziridines is developed with 1,4‐dithiane‐2,5‐diol to give 3,4‐dihydro‐1,4‐thiazines at room temperature. The use of Bi(OTf)3 as a catalyst, atom economy and regioselectivity are the important practical features.magnified image

Regioselective and stereospecific synthesis of functionalized 3,4-dihydro-2H-1,4-thiazines by catalyst-free [3 + 3] annulation of pyridinium 1,4-zwitterionic thiolates and aziridines

“…Punniyamurthy and co-workers reported another method for constructing such scaffolds through a Bi-catalyzed [3 + 3] cycloaddition between 1,4-dithiane-2,5-diols and aziridines via an S N 1 ring-opening/cyclization pathway (Scheme 1A-2). 10 However, owing to the S N 1 ring-opening pathway, racemic 3,4-dihydro-2 H -1,4-thiazine products will be produced even using enantiopure aziridines. Despite the impressive progress achieved, powerful strategies with wide substrate scope for synthesizing enantio-retained 3,4-dihydro-2 H -1,4-thiazines under catalyst-free conditions are still in great demand.…”