From 2-halothiazoles

Thiazolyl sulfamic acids, rearrangement of sulfonic acid, 70 rearrangement to sulfonic acid, 75 by sulfonation, 75 2-Thiazolyl sulfenyl chloride, transformation to, thiazolyl disulfides. 412 2-Thiazolyl sulfide, in hydrocarbon synthesis, 406 oxidation of, with m-chloroperbenzoic acid, 415 with CrOj, 415 with Hj02,405,415 with KMn04,415 physical properties, infrared, 405 NMR, 404 pKa, 404 ultraviolet, 404 preparation of, from 2-halothiazoles and 5-Thiazolyl sulfides, bis-5-thiazolyl sulfide, oxidation of, 415 general, 418 5-(2-hydroxythiazolyl)phenyl sulfide case, 418 physical properties, 418 preparation of, 417-418 table of compounds, 493-496 uses of. 442 2-Thiazolyl sulfinic acid, decomposition of, 413 preparation of, from 2-acetamidothiazole sulfonyl chloride, 413 from A-4-thiazoline-2-thione and H, 0, 393,413 table of compounds, 472-473 5-Thiazolyl sulfinic add, preparation of,... 

Large-scale reductive removal of the halogens is sometimes of preparative value thus it is convenient to remove chlorine from 4-chloroquinazoline [317], halogen from 2-halothiazoles [478, 479] and iodine from 4-iodophthalazines [306] by reduction at a mercury cathode, and chlorine from 2-amino-4-chloropyrimidine at a spongy cadmium electrode [480]. 

Halothiazoles are usually obtained from 2-aminothiazoles through the Sandmeyer reaction. Nevertheless, ammonolysis has sometimes proved useful for the preparation of 2-aminothiazole derivatives. Detweiler et al. (18) obtained 2-(u-pyridinylamino)thiazole (1) from 2-bromothiazole (Scheme 1). The reaction is easier if a nitro group occupies the 5-position of the thiazole ring (19-21). Ethylene diamine derivatives undergo this reaction with 2-haiothiazoles (22-24). 

Tertiary amines may be obtained from alkaline alkylation of secondary amines (46), but mixtures are obtained (see Section III.l.B) hence heterocyclization and ammonolysis of 2-halothiazoles are to be preferred. 

Since the exocyclic sulfur is more reactive in the ambident anion than in A-4-thiazoIine-2-thione. greater nucleophilic reactivity is to be expected. Thus a large variety of thioethers were prepared in good yields starting from alkylhalides (e.g.. Scheme 38 (54, 91, 111, 166-179). lactones (54, 160), aryl halides (54, 152. 180, 181), acyl chlorides (54. 149, 182-184). halothiazoles (54, 185-190), a-haloesters (149. 152. 177. 191-194), cyanuric chloride (151). fV.N-dimethylthiocarbamoyl chloride (151, 152. 195. 196), /3-chloroethyl ester of acrylic acid (197), (3-dimethylaminoethyl chloride (152). l,4-dichloro-2-butyne (152), 1,4-dichloro-2-butene (152), and 2-chloro-propionitrile (152). A general... 

Thioethers can be obtained either by heterocyclization (Chapter II) or from the reaction between 2-halothiazoles (102) and the sodium salt of... 

Sulfones and sulfoxides (145) are obtained usually from the corresponding sulfide by oxidation (Scheme 75) (341). though some of them were prepared from a halothiazole and metal sulfinate (342). 2-Amino-5-acetamidophenylsulfonylthiazole has been prepared by direct heterocycli-zation (343. 344). 

Ru, Os, and Ir carbene complexes have been prepared from reactions of anionic or low-valent metal complexes with some organic salts or neutral compounds with highly ionic bonds. Oxidative addition of halothiazole and -oxazole species to IrCl(CO)(PMe2Ph)2 affords Ir(III) complexes which on protonation yield cationic carbenes (69), e.g.,... 

Aminothiazole is easily diazotized in a concentrated solution of nitric and phosphoric acid. A large-scale procedure for the diazotization of 2-aminothiazole and its conversion to 2-bromothiazole has been reported . The synthesis of 2-halothiazoles can be easily achieved from 2-aminothiazole by (i) diazotization and (ii) treatment with CuCl, CuBr, or Nal <85JHC1621>. When the diazonium salt derived from 2-aminothiazole is treated with sodium azide the 2-azido derivative in equilibrium with its tetrazole cyclization product are obtained <92BMC1603>. 

The aryne 533 was also considered and rejected as an intermediate in the nucleophilic substitution of 5-halothiazoles (538) based on the following evidence only normal substitution to 539 is obtained, inconsistent with the expected formation of 535 from the aryne 533 as described above no exchange of the 4-proton is observed the reactivity of the 4-phenyl derivative 540, which cannot form the aryne 533, is similar to that of 538 and finally no aryne... 

---