Mercapto derivative

Mercapto derivatives of furan, thiophene, selenophene (77ACS(B)198) and pyrrole (72AJC985) all exist predominantly in the thiol form. 2-Mercaptobenzothiophene is also a thiol (70JCS(C)243i) whereas 2-mercaptoindole is mainly indoline-2-thione (89) (69CPB550). The finely balanced nature of this system is indicated by the fact that a 3-aryl, but not a 3-alkyl, substituent will stabilize the 2-thiol form, whereas for 3-aryl-fV-methyl derivatives the 2-thione tautomer is preferred (71CC836). 

The known 3-mercapto derivatives of furan, thiophene, selenophene (77ACS(B)198), ben-zothiophene (70JCS(Q243i) and indole (69TL4465) all exist as the 3-thiol tautomers. 

The preparation of 7,7-d2-cholesterol in 1950 was the first example of deuterium incorporation into steroids via desulfurization of mercaptals with deuterated Raney nickel. A substantially modified version of this reaction subsequently became the first widely used method for site-specific insertion of two deuteriums in place of a carbonyl oxygen. This conversion consists of the preparation of a mercapto derivative (84 85), which usually... 

According to the systematic nomenclature these substances were first named l-f-triazolo[d] pyrimidines in compliance with the general principles of the Ring Index/ More recent papers and Chemical Abstracts indexes use the term i -triazolo[4,5-d]pyrimidine (147) in accord with the lUPAC nomenclature. The numbering of substituents when using the last-mentioned name is different from that of the 8-aza analogs. For the formulas of oxygen and sulfur derivatives names derived from the lactim or thiolactim form are almost exclusively in use (in common with the purine derivatives). These derivatives are thus described as hydroxy and mercapto derivatives, respectively. The name 1,2,3,4,6-pentaazaindene is used only rarely for this system. 

The methods outlined, of course, are readily applicable to a wide variety of substituted heterocycles like the carboxyl, hydroxy and mercapto derivatives of pyridines, pyridine 1-oxides, pyrroles, etc. The application to amines and to diaza compounds such as pyrimidine, where the two centers are basic, is obvious except that now 23 takes the role of the neutral compound, 21 and 22 the roles of the tautomeric first conjugate bases, and 20 the role of the second conjugate base. Extensions to molecules with more than two acidic or basic centers, such as aminonicotinic acid, pyrimidinecarboxylic acids, etc., are obvious although they tend to become algebraically cumbersome, involving (for three centers) three measurable Kg s, four Ay s, and fifteen ideal dissociation constants (A ), a total of twenty-two constants of which seven are independent. 

The reversible hydration of nitrogen-containing heterocyclic bases and their hydroxy and mercapto derivatives is acid-base catalyzed and, at constant pH, the reactions obey first-order rate equations. 2 26.27-33... 

The nature and position of the cyclic heteroatoms within the five-membered rings of azoles can affect the positions of the prototropic tautomeric eqihbria, particularly of hydroxy and mercapto derivatives. 

The same starting compound 270 was also subjected to ring closure by using other reagents <2003PS1143> reaction of 270 with acetic anhydride afforded the methyl-substituted 272, whereas reaction with carbon disulfide yielded the 3-mercapto derivative 273. 

In West Germany pyridazinium compounds as represented by formula (120, R1 = halogen, alkyl, aryl R2 = H, alkyl R3 = substituted amino R4 = substituted alkyl, cycloalkyl) have been claimed as antibacterial agents [338]. In Australia, mercapto derivatives of several nitrogen heteroaromatics including pyridazine-derived compounds (121, R = CONH2, CH2NMe2) have been prepared in a search of amplifiers of phleomycin [339] however, only low activity has been observed in this series. 

The )V-(2,2-diethoxycarbonyl)vinyl derivative of cephalosporin C (34) was reacted with thiols in water at pH 6.5 at 60°C for 5-6 hr, or in boiling methylene chloride for 50 min, or in the absence of a solvent at 140°C for 15 min to give the mercapto derivatives (1584) (82EUP45717). When the mercapto derivatives (1584) first were reacted with dimethylaniline and dichlorodimethylsilane at 30°C for 10 min, the mixtures were then cooled to -10°C, and phosphorus pentachloride was added, followed by stirring at -5°C for 40 min, the 7-aminoceph-3-ene-4-carboxylic acid derivatives (1585) were obtained after work-up. 

On the other hand, Seto and Ogura (64BCJ1526) prepared isomeric thiazolotropone 193 as well as the 2-amino (191) and the 2-mercapto derivatives (192) from 3-aminotropolone (112) and dithiobenzoate 194, isothiocyanate, or carbon disulfide, respectively. 

Nitration of pyrido[l,2-f>]cinnolin-6-ium hydroxide inner salt 17 (R = H) and its 2-acetamide derivative afforded its 2-nitro and 2-acetamido-3-nitro derivatives, respectively. The reaction of 17 (R = H) with iodine monochloride afforded the 2-iodo derivative. The 2-cyano derivative was obtained from the 2-bromo derivative of 17 (R = H) with Cu(I)CN. Treatment of 17 (R = H) with P4S10 afforded the 11-mercapto derivative 41 (74JHC125). 

In an attempt to prepare tris(mercapto)amines of the type (CF3S)2-NSCF Cl3 n (w = 0, 1,2) from (CF3S)2NH and the appropriate sulfenyl chloride, it was observed that, besides the expected bis(trifluoromethyl-mercapto)derivatives, other products were also formed (57) ... 

In all the reactions discussed in this section, both isopropyl groups were transformed into a 1,2-dithiole ring. When N-alkyldiisopropylamines and sulfur monochloride were mixed in chloroform in the absence of another base, that is, DABCO, two monocyclic dithiole-3-thiones 93 and 94 were isolated. 5-Mercapto derivative 93 was the main product in all the cases examined (2001MC165, 2006RCB143 Scheme 45). 

Ptepd by treating the 3-mercapto deriv with hydrogen peroxide... 

Chloro, 3-bromo, 3-iodo, and 3-nitro derivatives of 5,7-dimethyl-pyrazolo[l,5-a]pyrimidine derivatives were prepared by chlorination, bromination, iodination, and nitration of 3-unsubstituted 5,7-dimethyl-pyrazolo[l,5-a]pyrimidines. Reaction with bromine and potassium thiocyanate gave a 3-thiocyanato derivative, which was converted into the mercapto derivative upon saponification. Nitrosation gives the 3-nitroso derivative and acylation with trifluoroacetic anhydride affords the trifluoroacetyl derivative (74JMC645 77JMC386). 

The Tautomerism of Heterocycles J. Elguero etal., Adv. Heterocycl. Chetn., Suppl. 1,1976. Ring-Chain Isomeric Transformations of Hydroxy-, Amino-, and Mercapto-Derivatives of Carbonyl Compounds and Their Heteroanalogues R. Valters, Russ. Chem. Rev. Engl. Transl.), 1974, 43, 665-678. 

Porphyrins can also be sulfonated a t the peripheral positions, and copper(II) porphyrins react with thiocyanogen to give the methine-thiocyanatoporphyrin which can be hydrolyzed to the corresponding mercapto derivative. Reactions between metalloporphyrins and car- benes are known, but they tend to give mixtures of products owing to addition at methine positions as well as across peripheral double bonds. Nitrenes also react with metal-free porphyrins to give insertion products and methine-substituted derivatives. 

N -Cyanocarbamimides (112) may be condensed with chloromethyleniminium salts in a similar way (equation 58). Yields are good to excellent, and reaction conditions are mild (Table 12) (81S907). The synthesis provides an easy route to 4-aIkoxy-2-chloro-l,3,5-triazines (113) and the-corresponding mercapto derivatives. 

Hydrolysis of the 2-acetylthioxy derivative (103 X = S) in aqueous methanol gave the 2-mercapto derivative, which was then desulfurized to 4-oxo-4H-pyrido[l,2- ]pyrimidine in 3"0 aqueous ammonia in the presence of Raney nickel.167 The same product was obtained in poor yield when 2-hydrazino-4-oxo-4f/-pyrido[l,2-u]pyrimidine was treated with a 15"/ solution of copper(ll) sulfate in aqueous acetic acid.255... 

The reaction of tetrachloropyridine 289 with sodium hydrosulfide giving only 4-mercapto derivative 290, which was transformed (1996KGS364) into compound 291 in 77% yield (with respect to mercaptopyridine 290) by 5-alkylation and Dieckmann cyclization, is another example of the application of this approach. 

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