Yamamoto, Yuzuru published the artcilePyridine derivatives containing sulfur. XXXI. Synthesis of pyridothiazoles and pyridoxazoles, Application In Synthesis of 31784-71-1, the publication is Yakugaku Zasshi (1951), 169-72, database is CAplus.
cf. C.A. 46, 112h. The following correction is made: 2-Amino-5-bromo- or 2-amino-5-iodopyridine and KCNS or Cu(CNS)2 do not form a pyridothiazole ring as reported (cf. C.A. 46, 111c, 112ad). To 2-chloro-5-aminopyridine (I) (3 g.) and 9.1 g. KCNS in 47 mL. 95% AcOH at -5 to -10° is added 1.26 g. Br dropwise, the mixture filtered, and 3 volumes H2O is added to the filtrate, which is again filtered and neutralized with Na2CO3 to give crude 2-amino-5-chloropyrido[3,2-d]thiazole (H) (C.A. numbering). Crude II recrystallized from MeOH gives 1.7 g. II, decompose 243-4°. 2-Hydroxy-5-aminopyridine and KCNS and Br in a similar way give the 5-HO analog (III) of II, m. 248-9°; acetate, needles, m. 286°. By using the 2-alkoxy analogs of I the following 5-alkoxy analogs of II are prepared similarly: MeO, needles or plates, m. 191-1.5°; EtO, needles or plates, m. 201-3°; iso-PrO, light yellow plates, m. 191-3°; BuO, plates, m. 139°; and iso-AmO, light orange needles, m. 126.5°. 2,5-Diaminopyridine and KCNS in 95% AcOH similarly give 2,5-diaminopyrido[3,2-d]-thiazole, m. 214-15°. 2,6-Diaminopyridine (3 g.) and 11 g. Cu(CNS)2 in AcOH after removal of the AcOH, solution of the residue in hot water, and precipitation with Na2CO3 give 0.8 g. 2,5-diaminopyrido[2,3-d]thiazole, yellow prisms, m. 137°. Treating 2 g. 2-amino-3-nitro-5-bromopyridine (IV) with 2.8 g. PCl5 4 h. at 120-40°, decomposing the excess PCl5 with ice water, filtering, and recrystallizing from MeOH give 1.4 g. 2-chloro-3-nitro-5-bromopyridine, yellow needles, m. 67-8°. Heating 1.5 g. IV in 6.5 mL. 85% HCl, adding 6.5 g. SnCl2 at 100° during a period of 3 h., drying in vacuo, making alk. with NaOH, and taking up with ether gives 0.5 g. 2-hydroxy-3-amino-5-bromopyridine (V), m. 182-4°. Boiling 0.5 g. V in 3 mL. Ac2O 40 min., filtering off the excess Ac2O, cooling, making alk. with Na2CO3, and taking up with AcOEt gives 0.3 g. 6-bromo-2-methyloxazolo[5,4-b]-pyridine, needles, m. 223-5°.
Yakugaku Zasshi published new progress about 31784-71-1. 31784-71-1 belongs to thiazole, auxiliary class Other Aromatic Heterocyclic,Chloride,Amine, name is 5-Chlorothiazolo[5,4-b]pyridin-2-amine, and the molecular formula is C28H29NO4, Application In Synthesis of 31784-71-1.
Referemce:
https://pubchem.ncbi.nlm.nih.gov/compound/thiazole,
Thiazole | chemical compound | Britannica