477-1,4-Thiazine, 3-ethyl-5,6-dihydro-2-methyl

Similar ring systems were prepared <97JHC1693> by Coppo and Fawzi from the reaction of substituted ethyl 5-[methyl(methylsulfonyl)amino]-l 7/-pyrazole-4-carboxylates 119 with sodium hydride. This gave the 7-substitued 1,7-dihydro-l-methylpyrazolo[3,4-c][l, 2]thiazin-4(37/)-one 2,2-dioxides 120 in fair to good yield (Scheme 30). They also extended this synthesis by treating methyl 2-[methyl(methylsulfonyl)amino]-6-(trifluoromethyl)-3-pyridinecarboxylate 121 with sodium hydride in dimethylformamide to yield l-methyl-7-(trifhioromethyl)-l//-pyrido[2,3-c][l,2]thiazin-4(3//)-one 2,2-dioxide 122 in 79% yield (Scheme 31) <98JHC499>. 

Thiazin 5-Cyan-2-ethyl-2-methyl-6-methylthio-4-oxo-3,4-dihydro- E14a/3, 510 [HS-C(SR)=C(CN) — CO-NHj + Keton]... 

Ethyl 9-ethoxycarbonyl- and 9-hydroxymethyl-3-methyl-6-oxo-2/f,6//-pyrido[2,l-Z>][l,3]thiazine-4-carboxylates were isomerized into 4H,6H-pyrido[2,l-b][l,3]thiazine-4-carboxylates by treatment with KOH overnight at room temperature and by treatment with NaOEt at 0 °C for 1 h and room temperature for 3h in EtOH, respectively. In another experiment, when the 9-hydroxymethyl derivative was treated with NaOEt in EtOH at — 10°C for 3h, a 2.5 1 mixture of ethyl 3,4-cw-H-9-ethoxymethyl-3-methyl-6-oxo-3,4-dihydro-2//,6//-pyrido[2,l-Z)][l,3]thiazine-4-carboxylate and the aforementioned 4//,6//-isomer were obtained (00JCS(P1)4373). 

Photolysis of the four examples of 2,3-dihydro-6f/-l,3-thiazines 101-104 resulted in the formation of different products which is dependent on R and R (Scheme 3). When both groups are methyl (101), isomeric thiazolines 105 and 106 are isolated, the thiazoline 106 being the major isomer. The ethyl analogue 102 reacts differently and the thioamide 107 is formed. All four thioamide isomers are formed when the benzyl analogue 103 is photolyzed and the... 

Thiamin hydrochloride Thiaminium chloride hydrochloride. See Thiamine HCI Thiamin nitrate. See Thiamine nitrate 5-Thianonane. See Butyl sulfide Thia-4-pentanal. See3-Methylthiopropionaldehyde 3-Thiapentane. See Ethyl sulfide Thiaphene. See Thiophene 2-Thiapropane. See Dimethyl sulfide Thiate EF-2. See Thmethylthiourea Thiate H. See 1,3-Diethylthiourea Thiate U. See 1,3-Dibutylthiourea 4H-1,3-Thiazin-2-amine, 5,6-dihydro-6-methyl-, (monohydrochloride)... 

Methyl (3R)-3,4-dihydro-3-iodomethyl-2,2-dimethyl-2H-l,4-thiazine-6-carboxylate refluxed 5 days in ethyl methyl ketone methyl (3R)-3,4-dihydro-3-isopropenyl-2H-l,4-thiazine-6-carboxylate. Y 61%, F. e. s. A. R. Dunn and R. J. Stoodley, Soc. Perkin I 1972, 2509. 

HgS passed 7 hrs. with vigorous stirring under Ng into a refluxing soln.of 2-methyl-3-ethyl-5,6-dihydro-4H-l,4-thiazine and n-butylamine in diloroform 2,2-di-ethylthiazolidine. Y 97% conversion 88%. F. e., alsoh reverse oxidative ring expansion with sulfur, s. F. Asinger, H. Offermanns, and D. Neuray, A. 739, 32 (1970). 

---