10514-31-5Relevant academic research and scientific papers
Phototransposition Chemistry of 4-Substituted Isothiazoles. The P4 Permutation Pathway
Pavlik, James W.,Tongcharoensirikul, Pakamas,French, Kathleen M.
, p. 5592 - 5603 (1998)
Upon irradiation in the presence of a small quantity of base, 4-substituted isothiazoles undergo photocleavage to yield substituted cyanosulfides, which can be trapped as their benzyl thioether derivatives, and substituted isocyanosulfides. Both products are suggested to arise via initial photocleavage of the sulfur-nitrogen bond, resulting in the formation of a substituted β-thioformylvinyl nitrene, which can rearrange to the observed cyanosulfide, or cyclize to an undetected thioformylazirine. Deprotonation of the azirine leads directly to the isocyanosulfide. The plight of the isocyanosulfide depends on the C-4 substituent. If the substituent is aromatic, the isocyanosulfide is reprotonated at the isocyanide carbon and spontaneously cyclizes to a 4-substituted thiazole, the observed transposition product. If the substituent is not aromatic, the isocyanosulfide is reprotonated at sulfur and the resulting species has a higher energy barrier to cyclization. In these cases, the isocyanosulfides can be observed spectroscopically and can be trapped as their N-formylaminobenzyl thioether derivatives.
Access to 4-substituted isothiazoles through three-component cascade annulation and their application in C-H activation
Huang, Guoling,Li, Jian,Ji, Xiaoliang,Chen, Lu,Liu, Qiang,Chen, Xiuwen,Huang, Yubing,Li, Yibiao
supporting information, p. 5763 - 5766 (2020/07/15)
The use of potassium ethyl xanthate (EtOCS2k) as a sulfur atom donor enabled the transition-metal-free [3 + 1 + 1] cascade annulation of isopropene derivatives with NH4I in DMSO/H2O, affording various 4-substituted isothiazoles in moderate to good yields
Phototransposition chemistry of phenylisothiazoles and phenylthiazoles. 1. Interconversions in benzene solution
Pavlik, James W.,Tongcharoensirikul, Pakamas,Bird, Nigel P.,Day, A. Colin,Barltrop, John A.
, p. 2292 - 2300 (2007/10/02)
Phenylthiazoles 1-3 and phenylisothiazoles 4-6 undergo phototransposition in benzene solvent mainly by P5, P6, and P7 permutation pathways. Phenylisothiazoles 5 and 6 also transpose via a P4 permutation process to yield phenylthiazoles 2 and 3 in less than 1% yield. In benzene saturated with D2O, 2-phenylthiazole (1) and 5-phenylisothiazole (6) each phototranspose to yield 4-deuterio-3-phenylisothiazole (4-D-4) and 4-phenylthiazole (2) without deuterium incorporation. Irradiation of 4-phenylthiazole (2) under these conditions results in rapid photodeuteration to yield 2-deuterio-4-phenylthiazole (2-D-2), which subsequently phototransposes to 5-deuterio-3-phenylisothiazole (5-D-3). These experimental results can be rationalized by a mechanism involving initial electrocyclic ring closure and sigmatropic shift of sulfur around the four sides of the azetine ring. Rearomatization of each bicyclic intermediate thus allows sulfur to insert into each position in the carbon-nitrogen sequence. As a consequence, these compounds divide into a tetrad in which isomers 1, 2,4, and 6 interconvert mainly via P5, P6, and P7 pathways and a dyad of two compounds in which 3 phototransposes to 5 via P5 and P7 pathways. Within the tetrad, BC-6, the bicyclic intermediate derived from 5-phenylisothiazoles (6), is postulated to undergo deuteration with simultaneous sigmatropic shift of sulfur when the reaction is carried out in benzene-D2O. This mechanistic view provides one coherent interpretation for the observed phototransposition and photodeuteration reactions.
