L- -2-mercapto

The same substrate (11) with 2,3-dimethylbut-2-ene gave l-(2-mercapto-1,1,2-trimethylpropyl)phthalazine (13) (MeOH, hv, 2h 71%) and thence 1-isopropylphthalazine (14) (vacuum distillation 31%) analogs likewise." ... 

Many mercaptoazoles exist predominantly as thiones. This behavior is analogous to that of the corresponding hydroxyazoles (c/. Section 4.02.3.7). Thus oxazoline-, thiazoline- and imidazoline-2-thiones (521) all exist as such, as do compounds of type (522). However, again analogously to the corresponding hydroxyl derivatives, other mercaptoazoles exist as such. 5-Mercaptothiazoles and 5-mercapto-l,2,3-triazoles (523), for example, are true SH compounds. 

Hydroxy and mercapto substituents at the 3- and 5-positions can also exist in tautomeric forms (see Section 4.01.5.2) and can be alkylated at either the substituent or the ring nitrogen atom. 3-Methoxy groups are not replaced by nucleophiles, but both 3- and 5-alkylthio groups react readily, as does 3-methoxy-l,2-benzisothiazole. Alkylthio compounds can be oxidized to sulfoxides and sulfones, and the latter readily undergo nucleophilic replacement. All the hydroxy compounds react with phosphorus pentachloride to give the chloro derivatives. 

Buta-1,3-diene, 1 -(2 -furyl)-pyrolysis, 4, 600 Buta-1,3-diene, 1-mercapto-thiophenes from, 4, 887 Buta-1,3-diene, 1 -(1 -methyl-2-pyrrolyl)-thermal cyclization, 4, 285 Buta-1,3-diene, l-(2-thienyl)-electrocyclization, 4, 748 Butadienes... 

Imidazole, 1 -hydroxy-2,4,5-triphenyl-3-oxides reactions, S, 455 Imidazole, iodo-nitrodehalogenation, 5, 396-397 Imidazole, 1-iodo-reactions, S, 454 stability, S, 110 Imidazole, 2-iodo-synthesis, S, 401 Imidazole, N-iodo-, S, 393 reactions, 5, 454 Imidazole, 4-iodo-5-methyl-iodination, 5, 400 Imidazole, 2-isopropyl-4-nitro-N-nitration, 5, 351 Imidazole, 2-lithio-reactions, S, 106, 448 Imidazole, 2-mercapto-l-methyl-as antithyroid drug, 1, 171 mass spectra, 5, 358 Imidazole, 1-methoxymethyl-acylation, S, 402 Imidazole, 5-methoxy-l-methyl-reactions... 

Thiazolonaphthyridines, 2-mercapto-halogenation, 6, 687 Thiazolo[4,5-6][l,7]naphthyridines applications, 6, 710... 

Related reactions are those of sodium azide with carbon disulflde to give 5-mercapto-l,2,3,4-thiatriazole (see 8ection IV) and with thio-carbonyl chloride to give 5-chloro-l,2,3,4-thiatriazole. ... 

From 4-phenylthiosemicarbazide Freund and HempeH obtained a product to which they assigned the structure of a tetrazolinethione. When heated in alkaline solution it was isomerized to a compound which, on the basis of adequate chemical evidence, was considered to be 5-mercapto-l-phenyltetrazole. According to Lieber and Ramach-andran, however, the initial product is 5-phenylamino-l,2,3,4-thia-triazole. Lieber and Slutkin have also converted some di(thiosemi-... 

In solutions of 3-mercapto-l, 2,4-triazoles the tautomeric equilibrium is shifted to the thione forms 181b (Scheme 65) [76AHC(S1), pp. 404, 415 96UK326]. Such an equihbrium was observed for 3-mercapto-5-ferrocenyl-4-phenyl-1,2,4-triazole 182 (94MI1121 96UK326). The thione tautomers 183 of 5-mercapto-l,2,4-triazoles are predominant [76AHC(S1), pp. 405, 414 97SA(A)699]. 

The tautomerism of 3-mercapto-l,2,5-triazole 184 has not been studied thus far. Very little information is available on the structure of 2-mercapto-1,3,4-triazole and its selenium analog, but apparently the thione 185 and se-lenone 186 forms are preferred for these compounds [76AHC(S1), pp. 408, 414]. 

Based on IR and NMR-spectroscopic studies [76AHC(S1), pp. 406, 414 94MI1027 96CHEC-II(4)267], 2-mercapto-l,3,4-oxadiazole prefers the thione form 195. 

No definite choice between the two tautomeric forms was made in early studies of 5-mercapto-l,3,4-triazolin-2-one 244 (Scheme 84) [76AHC(S1), p. 464]. The oxo-thione form 245, similar to 241, was attributed to 2-mercapto-4-hydroxyoxazole and its derivatives based on IR-spectro-... 

Aminolysis of the 5-substituted-2-mercapto-l,3,4-thiadiazolo[3,2-c]-quinazolinium iodides 119 with butylamine afforded the mesoionic 1,3,4-triazolo[l,5-c]quinazolines 120 [77IJC(B)1110] (Scheme 44). 

Hydrolytic fragmentation of the C5-N6 part took place upon heating 7-methyl-5-propyl-2-thioxo-l,2,4-triazolo[l,5-c]pyrimidine (129) with hydrochloric acid. 3-Acetonyl-5-mercapto-l,2,4-triazole (130) and butanoic acid were obtained as a result of N4-C5, C5-N6, and N6-C7 bond cleavages (65JCS3369) (Scheme 50). 

Triazole ring cleavage of the 7-amino-5-benzyl-5-mercapto-l,2,4-triazolo-[l,5-c]pyrimidinium iodide 135 at the N3-N4 bond occurred upon treatment with potassium carbonate to give the 4-amino-2-benzylmercapto-l-methyl-... 

Oxidation of 2-mercapto-l,2,4-triazolo[l,5-c]pyrimidines (174) with chlorine or bromine in water (64BRP951652 65JCS3369), with hydrogen peroxide and chlorine (95MIP1), as well as with sodium chlorate in hydrochloric acid (94JMC2371) gave the corresponding 2-sulfonyl halide derivatives 175. Oxidation of the 2-alkylmercapto compounds 176 to the 2-alkylsufonyl derivatives 177 was made with ammonium peroxodisulfate and sulfuric acid... 

The same diamine, when treated with carbon disulfide in alkaline medium, yielded 2-mercapto- l//-imidazo[4,5-/]quinoline (88PS267,88SC973,86IJC264), which, on treatment with alkyl, aralkyl, and acid halides, gave the corresponding thioethers and thioesters 111, respectively (88PS267, 86IJC264). 

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