Thione alkyl aryl

A -l,3,4-Oxadiazoline-5-thione, 4-alkyl-2-(4-pyridyl)-biological activity, 6, 445 A -l,3,4-Oxadiazoline-5-thione, 2-aryl-reactions... 

The reaction of 1-amino-1-deoxyketoses, and their N-alkyl and N-aryl derivatives, with alkyl or aryl isothiocyanates (Huber et al, 1960) was studied in more detail, and new 4-(alditol-l-yl)-l-alkyl(aryl)-3-alkyl(aryl)-l,3-dihydro-2H-imidazole-2-thiones were obtained. These compounds were used as starting materials for the synthesis of OL-histidines, DL-histidine-2-thiol, and other imidazole derivatives of biological interest. 

Publications on other types of rearrangements involving tetrazoles are cited at length in a review <2004SOS(13)861> in particular, the Smiles rearrangement of 2-[(l-alkyl/aryl-17/-tetrazol-5-yl)sulfanyl]pyridine-3-amines 208 to 3-[(l-alkyl/aryl-l/7-tetrazol-5-yl)amino]pyridine-2(l/f)-thiones 209 under acidic conditions and Smiles rearrangement of 5-sulfanyl/sulfone-substituted tetrazoles 210 to tetrazol-5-amines 211 under basic conditions (Scheme 19) <2004SOS(13)861>. 

The main route to A2-oxadiazoline-5-thiones (83 R1 = alkyl, aryl, C02Et, R2 = H) is the cyclization of dithiocarbazates (88) prepared from acylhydrazines (89 R2 = H) and carbon disulfide. The ester (83 R1 = C02Et, R2 = H), obtained by this method, has been hydrolyzed... 

The thiones (3b) are readily alkylated by alkyl halides, forming 3-alkylthio-l,2-dithiol-ylium salts (21 R = alkyl). Aryl halides are usually unreactive but do react under light catalyzed conditions to form 3-arylthio-1,2-dithiolylium salts (21 R = aryl) (79ZOR1069). 

Excitation of the alkyl aryl thione 443 with an activated (3-hydrogen into either the Si (n,7t ) or S2 (it,it ) state using different irradiation wavelengths was found to produce the cyclopropanethiol 444 via the same 1,3-biradical (Scheme 6.212).1274 In contrast to the reaction from the 17t,7t state, the product formation obtained by excitation into Si was quenched by a triplet quencher, indicating that the lowest (n,7t ) triplet must be the reactive state. Avery large isotope effect (kH/kD >17) found for this reaction indicates a substantial tunnelling effect (Special Topic 5.2) in the hydrogen abstraction process. 

Reaction of 2-alkyl/aryl isothiazol-3(2//)-thiones 90 with various alkyl-halogenides gave the 3-iS -alkyl-substituted isothiazolium salts 25a,91 in good-to-very-good yields (70BSF3076, 73CJC3081, 93JHC929, Scheme 29). Several isothiazolium iodides 25a,91a-n, perchlorate 25a and chlorides 91o-v were also synthesized. The structure of 2-methyl-5-aryl-isothiazolium chloride 91q, isolated in 60% yield, was confirmed by X-ray analysis. The S-alkylated isothiazolium salts 25a,91 with yields and references are represented in Table 5. 

Spectra.—Ultraviolet Spectra, The transient, extra absorption band which appeared in the 400—600 nm region (maximum absorption at ca. 475 nm) in the u.v. spectrum of thiobenzophenone as a result of the flash photolysis of this thione has been tentatively assigned to short-lived, triplet thio-benzophenone. " A similar species, generated in the same manner from Michler s thione, was found to exhibit absorption in the 470—520 nm region. " The influence of substituents (R) on the u.v. absorptions of 3-alkyl- and 3-aryl-6-methylthiouracils (368) has been studied, and, based on a comparison with the u.v. spectra of alkyl-, aryl-, and benzoyl-thioureas, the two bands at 280 nm and 240 nm (the intensities of which... 

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). 

Reactions of iV -alkylated or arylated azinium compounds with nucleophiles proceed more readily than those of the parent, uncation-ized azines, and the ring tends to open. The iV -substituent may bring into play an accelerative effect from the London forces of attraction. Increased displaceability of the substituent in iV -alkyl-azinium compounds has been noted for 2-halopyridinium (87) 1-haloisoquinolinium, 4-halopyrimidinium, 4-methoxypyrid-inium (88), 4-phenoxy- and 4-acetamido-quinazolinium (89), 3-methylthiopyridazinium, and 2-car boxymethylthiopyrimidi-nium salts (90). The latter was prepared in situ from the iV -alkyl-pyrimidine-2-thione. The activation can be effectively transmitted to... 

The reagent does not replace nitrogen atoms, and N-alkyl or N-aryl anthranilic acids yield 2,l-benzisothiazoline-3-thiones (94) on heating with phosphorus pentasulfide in xylene. Curiously, when alkyl iV-arylanthranilates are treated in the same way, only a very small proportion—less than 10%— of 94 is obtained. The major product (80%) is the cyclic phosphorus-containing compound (95), the identification of which gives some clue about the structures of possible intermediates.122... 

As with five-membered heterocycles, phosphorus pentasulfide may replace a ring oxygen atom by sulfur, or it may effect replacement in an acyclic precursor and then bring about cyclization. Thus isochroman-l-one (99) is converted into thioisochroman-l-thione (100) under the same conditions a 3-arylisocoumarin( 101) produces a 3-ary 1-1-thioisocoumarin (102) only, with no replacement of the ring oxygen atom.122 A typical example of thiation, followed by cyclization, is the formation of 2-alkyl- or 2-aryl-3,l-benzo-thiazine-4-thiones (103) from /V-acylanthranilic acid esters (104) by treatment with phosphorus pentasulfide in boiling xylene.122... 

Microwaves were used to support S-arylation of 5-substituted oxadiazoline-2-thiones <2000BMC69> and <2000M1207>. 5-(4-Pyridyl)oxadiazoline-2-thiones treated with 2-haloesters also afforded A-alkyl derivatives <2000CHE851>. A similar reaction occurred in the case of 5-pyrazolyloxadiazoline-2-thiones <2000JFA5312>. Organophosphorus derivatives of 1,3,4-oxadiazole were obtained by the reaction of bis(oxadiazolinethiones) with 0,0-diethylchlorophosphate (Scheme 21) <1998JFA1609>. 

When thioxo (or thiol) derivatives (as part of a thiourea function incorporated into the heterocyclic system) are present, effective. Y-alkylation is observed. Thus, the 3-heteroaryl-substituted [l,2,4]triazolo[3,4-/)][l,3,4]thiadiazole-6(5//)-thiones 37 dissolved in sodium hydroxide solution react with alkyl halides to afford the corresponding 6-alkylthio derivatives 38 (Equation 4) <1992IJB167>. The mesoionic compounds 39, inner salts of anhydro-7-aryl-l-methyl-3-methylthio-6-sulfonyl-[l,2,4]triazolo[4,3-A [l,2,4]triazolium hydroxides, are methylated with methyl iodide to give the corresponding quaternary salts 40 (Equation 5) <1984TL5427, 1986T2121>. 

The reaction of hydrazinapyrazoles 218 with acid halides also yields alkyl- and aryl-pyrazolo[5,l-c]-l,2,4-triazoles. Pyrazolo[5,l-c]-triazole-3-thiones are formed from 218 and carbon disulfide [77JCS(P1)2047]. 

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