Methyl 5-thio spectrum

The IR spectrum in Nujol of l,2,4-thiadiazolidine-3,5-dithione indicates that the dithione structure (18a) predominates. However, the dithione can be readily dialkylated on sulfur. Thus, treatment with 2,3-dichloropropene in aqueous sodium hydroxide forms (208 Scheme 73) (65AHC(5)119). The disulfenamide (209) condenses with aldehydes and ketones to give the corresponding imines (210) and (211 Scheme 74) (74ZOB2553). 5-Mercapto-3-methyl-thio-l,2,4-thiadiazole (212) reacts with di- -butyltin chloride in THF to give di-n-butyltin derivative (213 Scheme 75) (72USP3634442). 

Lumazine, 6,7-diphenyl-5,6-dihydro-properties, 3, 306 UV spectrum, 3, 279 Lumazine, 6,7-diphenyl-2-thio-glycosidation, 3, 297 reactions, 3, 300 Lumazine, 6,7-diphenyl-4-thio-reactions, 3, 300 Lumazine, 2,4-dithio-methylation, 3, 299 Lumazine, l-/3-D-glucopyranosyl-NMR, 3, 282 Lumazine, 1-hydroxy-structure, 3, 282... 

Mercapto-l,2,4-thiadiazoles are distinctly acidic. The pK of 5-thio-3-methyl-l,2,4-thiadiazole at 25°C is 5.18 <65AHC(5)119>. The position of equilibrium in the tautomers of 5-thio-l,2,4-thiadiazoles (10) (R = H) appears to be on the thione side (11) or (12). The solid state IR spectrum of (10) (R = Ph) shows no sign of SH absorption <92PS(66)32i>. However, treatment of (10) (R = Ph, / -Tol) with diazomethane does not produce any A-methylated products, but only the 5-methyl derivatives (137) (R = Ph, /)-Tol). Methylation of (10) (R = Ph) with methyl sulfate and with methyl iodide in sodium hydroxide gives only the S-methyl derivatives (137) (Scheme 31) <92PS(66)321>. In 1989 Yousef et al. reported that (10) (R = Ph) reacted with aromatic sulfenyl chlorides and with formaldehyde to give the A-substituted products (26) and (27) (Scheme 31). At the same time, alkylation... 

Cyclization at the hydroxylamine also occurs in the hydrogenation of l-nitro-2-thio-cyanatobenzene (30) to give 2-aminobenzothiazole 3-oxide (31) (Scheme 9.14).157 The hydrogenation over Raney Ni in ethanol at room temperature and 0.3 MPa H2 was complete after several hours with absorption of 2 mol of hydrogen to give crude 31 in 75-88% yield. The infrared spectrum of the product 31 indicated the presence of an equilibrium between 31a and 31b. Under similar conditions but with use of platinum oxide in tetrahydrofuran, 31 and its 5-methyl, 5-methoxy, and 5-chloro derivatives... 

The best known of the potential mercaptoimidazoles are the imidazoline-2- and benz-imidazoline-2-thiones, which resemble imidazolin-2-ones in that the tautomeric form (53 X = S) is the preferred form. The crystal structure and the HNMR spectrum of 1,3-dimethyl-3H-imidazoline-2-thione have been interpreted as showing partial double bond character in the N—C—N system, but no aromaticity (70CC56). However, the preference for a betaine structure (56) rather than (57) or (58) should be accepted with caution since it is really only a resonance structure similar to others which undoubtedly contribute to the overall structures of oxo-, thio- and amino-imidazoles. Measurement of the piSTa values for a series of imidazoline-2-thiones substituted variously on C-4, C-5, N-1 and N-3 by hydrogen, phenyl or methyl shows that all of the values are similar. Approximate Kr values calculated show that these compounds exist even more in the thione forms (53, X = S 58) than do the corresponding thiazoline-2-thiones and oxazoline-2-thiones. The UV spectra in aqueous solution support thione structures, as do dipole moment and X-ray studies (76AHC(S1)280, p. 400). 

The reaction of 5-amino-5-deoxy-l,2-0-isopropylidene-a-D-xylo-furanose (15) with methanolic hydrogen chloride (0.5 %), under careful exclusion of moisture, results in a mixture of the anomers of methyl 5-amino-5-deoxy-D-xylofuranoside, from which the /8-D anomer crystallizes. The five-membered ring-structure was proved by the results of periodate oxidation and by the infrared spectrum of the tetraacetate, which shows a band for NH. A methyl pyranoside was not found, and 3-pyridinol (21) was formed only in traces. A spontaneous ring-enlargement, such as is observed under similar conditions with 1,2-O-isopropylidene-5-thio-a-D-xylofuranose (see p. 208), is not possible in this instance. Stabilization as the methyl fiiranoside is, apparently, so rapid that the secondary reaction (leading to the pyranose form) does not occur. If water (several percent) is added to the reaction mixture, glycoside formation is hindered, and a large proportion of 3-pyridinol is formed. ... 

The acetolysis of S-acetyl-l,2-0-isopropylidene-3,5-di-0-methyl-6-thio-a-D-glucofiiranose with acetic acid—acetic anhydride—sulfuric acid gave a small yield of the crystalline septanose triacetate (271). The septanose structure of 271 was established by the absence of the thiol band in its infrared spectrum, and by the signals for three O-acetyl and two O-methyl groups found in its nuclear magnetic resonance spectrum. 

The synthesis of 3-azido-3-deoxy-5-tliio-/i-D-ribopyranose (288) was realized" from the tosylate 286 via thioacetate 287 in five steps (Scheme 76). Treatment of287 with acidic methanol gave a septarable 1 2 mixture of the methyl a-and / -pyranosides. The a anomer 288, whose H NMR. spectrum suggested an equilibrium of the C4 and " Q conformations, was transformed into 289 by conventional reactions. l,2,3-Tri-6 -acetyl-3-azido-3-deoxy-5-thio-D-xylopyranose was prepared via the xylo analogue of 286, starting form D-glucose."" " ... 

Extensive MO calculations for bond lengths and angles of l-phenyl-2-thio-5-carbomethoxymethylhydantoin have been reported.218 He(I) excited photoelectron spectra of hydantoin and 1-methyl-hydantoin are assigned by comparison with the spectrum of succinimide and by INDO/S calculations.219... 

Cefminox. [6R-[6a,7thio]methyl]S-oxo-S-thia-I-azabicyc (o-[4.2.0]oct-2-ene-2-carboxytic add 7,5-t2-1 -amino -2-ea rb-oxyethy]thioacetamido)-7 -methoxy-3-[[(l -methyl-12f-tetrazol 5-yl)thio]methyl]-3-cephem -4 -carboxylic acid. C)6HnN707S3 mol wt 519.57. C 36.99%, H 4.07%, N 18.87%, O 21.56%, S 18.51 %. Semisynthetic broad spectrum cephamycin antibiotic. Prepn Belg. pat. 880,686, K. 

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