Thiocarboxylates, 0-methyl

Methyl fluorene-9-thiocarboxylate Methyl fluorene-9-thionocarboxylate Methyl fluorene-9-carboxylate... 

S,3R). Secondly, the t/treo-3-methyl-D-cysteine (25,35) was prepared using the previously described addition of thiocarboxylic acid to threonine-derived aziridines. 62 ... 

Ca, Sr, and Ba carboxylate, thiocarboxylate, thiocarboxylate-carboxylate, sulfito, and sulfonate compounds and their monodentate base adducts are white solids, many of which decompose on melting and are only soluble in protic solvents such as alcohols and water.I68-232-240 They are invariably oligomeric or polymeric in the solid state see, for example, Refs. 235, 239, and 240. On thermolysis, the nonfluorinated carboxylates degrade to the metal carbonates while their fluorinated congeners usually form the metal fluorides.212 222-262 269 The thiocarboxylates give mixtures of the metal oxides and sulfates on thermolysis in air.238-239 270 The methyl-thiocarbonate compound, Ca[(OCS)OMe]2(MeOH)3 2, is a dimer in the solid state, soluble in polar coordinating solvents and stable under reduced... 

Other miscellaneous additions reported include the photoaddition of thiocarboxylic acid to 3,4-diallyl-1,6-propano-1H,6H-3a-thia (S )-1,3,4,6-tetraazapentalene-2,5(3H,4H)-dithione, the Paterno-BUchi addition of methyl vinyl sulphides to benzophen-... 

Methyl thiocarboxylates are very suitable for the V-thioacylation of V-unprotected amino acids. Thus, shaking a heterogenous mixture of PhCSOMe in ether and the amino acid in aq. NaOH gives g(X)d yields of V-thiobenzoylated material. Using (9-alkyl thiocarboxylates of amino acids (2 R = R NHCHR ), the approach has been extended to synthesize endothiopeptides such as (5) formation of imidates may interfere with the desired process. The reaction has been carried out in water/THF using NazCOj or as shown in equation (3). ... 

DCC can be used to prepare 5-alkyl and 5-aryl thiocarboxylates (1) from carboxylic acids and thiols according to equation (5). This method has been successfully applied to the synAesis of thiol esters with sensitive substituents, e.g. 5-methyl thioacrylate, a natural product. In particular, N-protected amino acid and peptide 5-phenyl esters, which are useful building blocks in peptide synthesis, are obtained in excellent yields without racemization. N-Hydroxyphthalimide and DMAP have been used as cocatalysts to facilitate the reaction. The preparation of the Wittig reagent (5) by this route is shown in equation (6). 

Methyl and S-aryP thiocarboxylic esters can also be prepared directly from carboxylic acids if thiocyanates or chlorothioformates are used instead of thiols (equations 11 and 12). 

By addition of thiols to isonitriles thioformimidates (274 equation 147) are accessible. 2-Methyl-propaneisonitrile inserts into the thietane system to give triiminothiolanes (275 Scheme 42). A related insertion of isonitriles into a C—S bond was observed in the reaction of alkylmercaptocyanoacetic acid esters, labile thioimidates (276) are the products. - The addition of thiocarboxylic acids to isonitriles, giving mixed anhydrides of thioformimidic acids and carboxylic acids has been studied. ... 

Prop-2-ynyl)-5-(trifluoromethyl)-l, 3,4-thiadiazol-2(3//)-one (19) reacts with nucleophiles (ammonia, pyrrolidine, or potassium methylthiolate) with formation of 6-methylene-2-(trifluo-romethyl)-5,6-dihydro-4//-l,3,4-thiadiazine-4-carboxamides 20a, b or S-methyl 6-mcthylene-2-(trifluoromethyl)-5,6-dihydro-4//-l,3,4-thiadiazine-4-thiocarboxylate (20c).82 The action of aqueous sodium hydroxide on 19 gives rise to the 4//-1,3,4-thiadiazine 20d, which also bears an exocyclic methylene group.82... 

Methylation with dimethyl sulfate also converts thiocarboxylic acids into their methyl esters,446 and sulfites into aliphatic sulfonic acids. 

S-Methyl thiocarboxylates. Ketene S,S-dimethylacetals (1) can be hydrolyzed to S-methyl thiocarboxylates (2) by trifluoroacetic acid in water. Ketene thioacetals derived from 1,3-dithiane are unchanged by this procedure. ... 

The syntheses of 5-thio-D-arabinose and -lyxose have been achieved conventionally by thiocarboxylate displacements on 5-sulphonate ester derivatives of these sugars, and their methyl glycosides were also prepared, both anomers being obtained. Methyl 5-thiopentopyran-osides (D-arabino. L-lyxo, D-ribo. and D-lyxo derivatives) have also been prepared from methyl 5-thio-3-0-tosyl-o<-D-xylopyranoside as outlined in Scheme 1. The syntheses of S-(5 -deoxy-5 -adenosyl)-(+)-2-methylhomocysteine (14.) has been achieved in two steps from (+)-2-methyl-homocysteine. Methyl 2-0-tosyl-4,6-thioanhydro-K-... 

L-Kynurenine obtained from for the degradation of tryptophan is hydroxylated by a KMO homolog encoded by qbsG. The 3-hydroxy-kynurenine could be transam-inated into xanthurenic acid by the QbsB protein. The bifunctional protein QbsL activates xanthurenic acid via its N-terminal AMP (adenosine monophosphate) lig-ase domain, whereas the C-terminal domain of QbsL is responsible for the addition of the methyl group. QbsCDE proteins transfer sulfur from an unknown sulfur donor molecule. The participation and exact role of QbsK, a putative oxidoreductase, was not clear. Quinolobactin was proposed to result from the spontaneous hydrolysis of 8-hydroxy-4-methoxy-2-quinoline thiocarboxylic acid 17 [18]. 

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