Alkylthio - substituted

The photolysis of 4-substituted 2,3-dimethyl-3-isoxazolin-5-ones has been studied. Irradiation in methanol or ethanol with a 100 W high-pressure mercury lamp through a Pyrex filter of a 4-phenylthio compound produced a semithioacetal (Scheme 5). In contrast, an H, Cl or OPh moiety gave no reaction. The use of alkylthio substitution gave similar products. Cyclic compounds yielded cyclic products (Scheme 5), and the photolysis of (29) in benzene... 

Alkylthio-substituted allylboronates have also been prepared27. The ethylthio -isomer, however, was prepared with only 70% isomeric purity. 

The reaction of 3,4-bis(benzenesulfonyl)furoxan with alcohols and thiols in basic media affords a variety of alkoxy-and alkylthio-substituted (benzenesulfonyl)furoxans. For these derivatives a paramount problem is to determine the position (3- or 4-) of the substitution in the furoxan ring. The structures of these derivatives were assigned on the basis of both chemical and NMR evidence. In particular, 13C NMR substituent constants were obtained by NMR study of suitable furoxan models. By assuming a complete additivity of the substituent effects at the furoxan ring, these values were used for structural determination <1997FES405>. 

Reaction of 3,4-bis(phenylsulfonyl)-l,2,5-oxadiazole oxide isomers with ethanol and ethanethiol in basic medium gave the expected alkoxy- and alkylthio-substituted (benzenesulfonyl)furoxans, respectively <1996JHC327, 1997FES405>. Nucleophilic substitution of the sulfonyl group of 3,4-bis-(benzenesulfonyl)furoxan 222 in the presence of aqueous NaOH in tetrahydrofuran (THF) furnished the corresponding 3 -0-(3-benzenesulfonylfur-oxan-4-yl) derivative 223 in 79-92% yield (Equation 44) <2004JME1840>. 

Cyclisation of an NH amide toward a cyclic thionium ion was described for the synthesis of a tetrahydropyrrolo-[l,2-tf]pyrimidine-2,6(l//,7//)-dione 351. Compound 349 was transformed to 351 in two steps. The first one is the formation of a transient alkylthio-substituted lactam 350 from amidothioacetal 349 in the presence of dimethyl-(methylthio)sulfonium tetrafluoborate (DMTSF) followed by intramolecular cyclization <2000JOC235>. 

BTDM-TTF is one of the most powerfnl donors of the TTF class. Alkylthio-substitution, such as in BEDT-TTF (ET), leads to a slight redaction in its electron-donor ability. Nevertheless, salts of this cation-radical with tetracyanoqninodimethide (TCNQ) and its derivatives show significantly higher conductivity (by ca. 10 -10 ) than the analogons BTDM-TTF salts (Grossel and Weston 1994). This reflects some enhancement of intra and interstack interactions produced by the sulfur atoms at the edges of the donor skeleton. 

Wu N, Saito G, Imaeda K, Shi Z, Mori T, Enoki T, Inokuchi H (1986) Uncapped alkylthio substituted tetrathiafuivaienes (TTC -TTF) and their charge transfer complexes. Chem Lett 15 441 4... 

Saito G, Enoki T, Toriumi K, Inokuchi H (1982) Two-dimensionality and suppression of metal-semiconductor transition in a new organic metal with alkylthio substituted TTF and perchlorate. Solid State Commun 42 557-560... 

The protonation of 185 and 186 with trifluoroacetic acid (TFA) gave 4-(/i t/-butylthio)-3,6-diphenyl- 193 and 4-(ter1-butylthio)-3,6-di(2-thienyl)thieno[3,4-f]thiophene-l(3//)-thione 194 (Scheme 18). The treatment of 193 with sodium hydride and then isopropyl iodide led to 4-(/i< t/-butylthio)-3,6-diphenyl-l-(isopropylthio)thieno[3,4-f]thio-phene 195 by the regeneration of the thieno[3,4-f]thiophene ring system, thus making possible the synthesis of other alkylthio-substituted thieno[3,4-(r]thiophene derivatives. When the reaction of 185 with TFA was carried out... 

Many carbanionic nucleophiles that would be considered too hard to react as Michael donors can be made into effective reagents for conjugate addition reactions by appending resonance or inductively stabilizing groups to soften their intrinsic Lewis basicity. Such stabilized anionic Michael donors include enolates, alkylthio-substituted carbanions, ylides and nitro-substituted carbanions. 

Polyglymes offer a viable alternative as solvents to the potentially carcinogenic HMPA.1871188 Alkyl and phenyl sulfides were prepared from the reaction of suitable aryl halide precursors and an excess of sodium thiolates in tetraglyme.188 By the same procedure 2-(alkylthio)-substituted (alkyl = Me(CH2)n n = 3, 15,17) quinolines, pyrimidines and pyrazines were prepared from the corresponding chlorides.187... 

Amino-l,2,4-thiadiazoles are weak bases. The basicity is further decreased by 3-alkylsulfonyl and 3-alkylthio substitution but increased to a slight extent in compounds containing the 3-dialkylamino group. 3-Amino-l,2,4-thiadiazoles are generally much weaker bases than the 5-amino isomers (65AHC(5)ll9). Crystalline picrate and p-toluenesul-fonate salts of amino-l,2,4-thiadiazoles are readily prepared and the formation of insoluble 1 1 complexes with silver nitrate has been reported. 

Crystalline dimers of type (27) have been synthesized under thermal conditions for the first time from phenylacetic acid derivatives (25) (79CB1650). The structure of (27 R = Me) was established by X-ray analysis (78TL671). The dimer (27 R = Me) is stable in solution, whereas the analogous alkylthio-substituted dimers are in a temperature and solvent dependent equilibrium with the monomeric 1,3-dithiolone (26). The monomers (26), generated from the dimers (27), display the same propensity towards [3 + 2] cycloaddition as do the mesoionic dithiolones which are generated in situ from the precursors (25). A photochemical dimerization of (9) has also been described (80CL717) (see Section 4.32.3.1.8(iii)). 

M. Mizuno, A. F. Garito, and M. P. Cava, Organic metal Alkylthio substitution effects in tetrathiafulvalene-tetracyanoquinodimethane charge transfer complexes, J. Chem. Soc. Chem. Commun. 18-19 (1978). 

R2 = hydroxy, alkoxy, alkylthio, substituted alkyl, substituted phenyl, o-hydroxyphenyl... 

The intramolecular addition of cysteine thiyl radicals (CysS ) to phenylalanine yielding alkylthio-substituted cyclohexadienyl radicals was observed in Cys-Phe and Phe-Gly-Cys-Gly peptides.CysS radicals were generated by pulse irradiation of aqueous solution containing the respective disuHide-linked peptide [reactions (11)-(14)] ... 

There are, however, many pieces of evidence that the cysteine link only causes small perturbations in the electronic structure and energetics of tyrosine. Electrochemical experiments by Whittaker et al [31] showed that the p fiTa of o-methylthiocresol was only 0.7 pH units lower than for cresol (9.5 vs. 10.2). Babcock and co-workers have shown, based on EPR and ENDOR experiments on both apo-enzyme and model alkylthio-substituted phenoxyl radicals, that the sulfur cross-link only induces small perturbation in the spin distribution of the tyrosyl radical [32]. No big shift in the g-tensors between unsubstituted and methylthio-substituted radicals was observed. Since this kind of shift is expected when heavy elements carry some of the spin in organic radicals, the conclusion was that the sulfur center possesses only a small part of the unpaired spin. We have conducted ab initio multiconfigurational linear response g-value calculations of unsubstituted and sulfur-substituted phenoxyl radicals and shown that the shift in g-tensor is as small as 0.0008 in the gxx-component (2.0087 vs. 2.0079 in t). The other components were virtually unchanged, thus confirming the experimental results [33]. 

Alkoxy- and alkylthio-substituted aminothienopyrimidines 94 were prepared by cyclization of the corresponding isoureas and isothioureas 95. Isoureas are generated in situ from thiophenes 30 with cyanates in the presence of acids (1984INDP151496). Isothioureas are produced by alkylation of thioureas 33 (1991GEP287503). 

Figure 2 In the peptide Phe-Gly-Cys-Gly (formed by Phenylalanine, Glycine, Cysteine and Glycine amino adds linked by peptidic bonds), the sulphur atom is very close to the phenyl ring. An Intramolecular addition ofthe CysS radical on the aromatic ring of Phe (marked with an arrow) leads easily to the alkylthio-substituted cyclohexadie-nyl radicals. A tom colors Cyan carbon blue nitrogen red oxygen yellow sulphur. H atoms are not shown.

Ring expansion can occur during the fragmentation of methylisothiazoles (Scheme 2) and alkylthio-substituted isothiazoles (730MS(7)463, 72CR(C)1871). An interesting feature of... 

---