Thiazole-5-thiones

3-Thiazole-5-thiones (Anhydro-5-mercapto-l,3-thiazolium Hydroxides) (109) 

Monocyclic l,3-thiazole-5-thiones (109) are easily prepared by 1,3-dipolar cycloaddition of carbon disulfide to meso-ionic l,3-oxazol-5-ones (66)44,62 and l,3-thiazol-5-ones (105). Polycyclic meso-ionic 1,3-thiazole-5-thiones (110) 9-71 are formed from carbon disulfide and azomethine ylides (111) derived from isoquinolinium iodides and base. 

The meso-ionic l,3-thiazole-5-thione (112)68 is formed from N-thiobenzoylproline and warm thiolactic acid. 

The constitution (110, Ar = p-Br. C6H4) was Firmly established by X-ray crystallography.72 The corresponding derivative (110, Ar = p-02N. C6H4) yields a methiodide which gives meso-ionic l,3-diazole-4-thiones (103) with primary aliphatic amines.72b The meso-ionic 1,3-thiazole-5-thiones (109) give the salts (113) with methyl iodide.39 

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Figure 3.7 Complex obtained by reaction of [Au(C6F5)(tht)] with 4-methyl-3H-thiazole-2-thione.

In the middle of the 1950s, Knott reported the synthesis of dyesmffs based on benzothiazole derivatives. Alkylation of Al-methylbenzo-l,3-thiazole-2-thione with a-bromoacetophenone and deprotonation of the resulting thiocarbonylium salt 5 yielded, after spontaneous desulfurization of the intermediate thiirane (7), the alkylidene derivative 8 (18) (Scheme 5.1). In order to rationalize the reaction, thiocarbonyl ylide 6 was proposed as the precursor of thiirane 7. To the best of our... 

The thiazole-2-thione (51) with an a-halo ketone gives the intermediate (52) which is cyclized by strong acid into the thiazolo[2,3-/ thiazolium salt (53) (77HC(30-i)l). A wide variety of [5,5]-fused systems are prepared in this way. 

Other thiohydroxamic acid derivatives have been used for the generation of radicals. Acyl derivatives of iV-hydroxythiazole-2-thione (75) have been explored by Barton as precursors for carbon radicals [86JCS(P1)39]. It has also been shown that similar precursors can be used for the generation of dialkylaminium cation radicals, N-hydroxy-4-methyl-thiazole-2-thione carbamates, TTOC carbamates 76 (91JOC1309). In contrast to... 

Monoalkyl aminium radicals cannot be prepared from PTOC carbamates 29 due to an equilibrium in solution favoring 2-mercaptopyridine-Ar-oxide and an alkyl isocyanate [Eq.(ll)]. With Af-(monoalkyl)thiazole-2-thione carbamates, TTOC carbamates, the equilibrium lies far to the side of the carbamate 84, and these precursors can be prepared from an isocyanate and Ar-hydroxythiazole-2-thione [Eq. (12)]. Under UV photoinitiation in acidic media, TTOC carbamates are efficient precursors for monoalkyl aminium cation radicals (Scheme 26). Monoalkylaminium radical 85 ey-clizes as efficiently as its analogous dialkylaminium radical 66, and the resulting carbon radical 86 can be trapped by a variety of radicophiles (91JOC1309) to prepare substituted pyrrolidines. 

Oxygen-sulfur heteroatom exchange has been achieved with 3-methyl-benzene thiazole-2-thione in the presence of trifluoroacetic acid and with l-phenyl-5-mercaptotetrazole. Thiirane can be prepared from oxirane on a support impregnated with alkali metal salts, by decomposition of the dithiocarbon-ate formed with carbon disulfide. A macrocyclic ether, perhydrobenzo-18-crown-6, plays a role in the nucleophilic reaction of oxirane with KCNS, which leads to thiirane in good yield. ... 

If R3 or R4 is a 2-hydroxyethyl group or a 2-acetoxyethyl group, treatment with hydrochloric acid yield 3-(2-methyl-4-amino-5-pyrimidi-nylmethyl)-2,3,3a,5,6,6a-hexahydrofuro[2,3-d]thiazole-2-thione (CXCVI) with liberation of water or acetic acid (Table 21). On further hydrolysis with acids the tetrahydrofuran ring opens again and 3-(2-methyl-4-amino-5-pyrimidinylmethyl)-4-methyl-5-(2-hydroxyethyl)-/l4-thiazoline-2-thiones are obtained (Table 29)-... 

The interaction of ammonia with carbon disulfide produces ammonium dithiocarbamate in solution, which reacts with 2-halo-ketones to produce thiazole-2-thiones similarly, methyl dithiocarbamate serves as a component for the construction of 2-methylthiothiazole, reducable to thiazole itself by hydrogenolysis, thus providing a good route to the unsubstituted heterocycle. °... 

Thiazole-2-thione reacted with Br(CH2)3Br to give, mainly, a salt C6HgNS2" Br suggest a structure and a mechanism for its formation. 

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