Mono sulfoxides

Pihl, A., and Lange, R. (1962) The interaction of oxidized glutathione, cystamine mono-sulfoxide, and tetrathionate with the -SH groups of rabbit muscle D-glyceraldehyde 3-phosphate./. Biol. Chem. 237, 1356-1362. 

Macrocyclic sulfoxides and sulfones have begun to attract interest as phase transfer catalysts <81H(16)1701, 86JCS(Pi)465> they are best obtained by oxidation of the parent crown thioether. By way of illustration, mono(sulfoxide) of 9S3 has been isolated as an iron(II) complex (Section 9.30.3.4), while the tris(sulfone) can be prepared from 9S3 with excess permanganate <871C3762>. Cyclic sulfones extrude SO2 at 500°C (60-80 Pa) to give cyclophanes <89JOC2632,90CC1066>. 

Methyl-substituted cyclic sulfides can be expected to undergo oxidation by cytochrome P450 enzymes to produce the corresponding sulfoxides (Takata et al., 1983). The mono-sulfoxides are predicted to be the main urinary metabolites of simple cyclic sulfides. 

The seleno derivative 1374, which can be readily prepared by reduction of di-phenyldiselenide with sodium borohydride then alkylation with chloromethyltri-methylsilane, is alkylated to 1375 to give, on oxidative hydrolysis, aldehydes 1376 in high yields, PhSe02H-H20 1377 [104], and 7 (Scheme 8.44). Alkylation of the commercially available methyl thiomethyl sulfoxide 1378 leads to mono- or dialkyl... 

In the presence of a suitably disposed /i-hydrogen—as in alkyl-substituted thiirane oxides such as 16c—an alternative, more facile pathway for thermal fragmentation is available . In such cases the thiirene oxides are thermally rearranged to the allylic sulfenic acid, 37, similarly to the thermolysis of larger cyclic and acyclic sulfoxides (see equation 9). In sharp contrast to this type of thiirane oxide, mono- and cis-disubstituted ones have no available hydrogen for abstraction and afford on thermolysis only olefins and sulfur monoxide . However, rapid thermolysis of thiirane oxides of type 16c at high temperatures (200-340 °C), rather than at room temperature or lower, afforded mixtures of cis- and trans-olefins with the concomitant extrusion of sulfur monoxide . The rationale proposed for all these observations is that thiirane oxides may thermally... 

In pyridine- X-C interactions, the C - X moiety is roughly coplanar with the pyridine and the two C-N- X angles are approximately 120° [129,143, 144]. The same holds for other nitrogen heteroaromatics (e.g. pyrazine, quinoline, etc.) [145-147]. A carbonyl group pins the donors after a trigonal planar geometry and works either as a mono- [148,149] or bidentate XB acceptor [150]. Sulfoxides behave similarly [151,152] and imines form XB along the expected axis of the lone pair [153]. 

A prochiral bis(cyanomethyl) sulfoxide was converted into the corresponding mono-acid with enantiomeric excesses as high as 99% using a nitrilase-NHase biocatalyst. The whole-cell biocatalyst Rhodococcus erythropolis NCIMB 11540 and a series of commercially available nitrilases NIT-101 to NIT-107 were evaluated in this study. As outlined in Figure 8.18, the prochiral sulfoxide may be transformed into five different products (plus enantiomeric isoforms), of which, three are chiral (A, B, and C) and two achiral (D and E). Only products A, B, and E were observed with the biocatalysts employed in this investigation. Both enantiomerically enriched forms of both A and C could be obtained with one of the catalysts used. The best selectivities are as follows (S)-A 99% ee, (R)-A 33% ee, (S)-C 66% ee, and (R)-C 99% ee, using NIT-104, NIT-103, NIT-108, and NIT-107 respectively. Each of these catalysts produced more... 

Figure 8.18 Conversion of a prochiral bis(cyanomethyl) sulfoxide into the corresponding mono-acid using a nitrilase-NHase biocatalyst...

Reaction of compound 37 with bromine in chloroform results in mono-bromination a to the sulfur. Treatment of this brominated derivative with NaBH3CN in AcOH gives a mixture of products resulting from reduction of the C=N double bond and of elimination of HBr. Reaction of 44 with sodium ethoxide results in the ethoxy-substituted derivative 45, whereas reaction with pyridine gives the dehydrobrominated derivative 46. Reaction of either 44 or 46 with sodium cyanide in dimethyl sulfoxide (DMSO) gives the cyano-derivative 47 <1983HCA971> (Scheme 13). 

Bajugam and Flitsch [217] have described the synthesis of glycosylamines from mono-, di-, and trisaccharides by direct microwave-assisted Kochetkov amination (Scheme 6.110). The reaction was found to be effective with just a fivefold excess (w/w) of ammonium carbonate with respect to the sugar, as compared to the 40-or 50-fold excess needed under thermal conditions. All transformations were completed within 90 min in dimethyl sulfoxide as solvent, maintaining the vessel temperature at an apparent 40 °C using the heating-while-cooling technique (see Section 2.5.3). 

Addition of 1,5-dithiacyclooctane to zeolite CaY in the presence of molecular oxygen results in spontaneous oxidation to mono- and bis-sulfoxides through formation of the corresponding radical cation characterized by ESR and diffuse reflectance of UV-Vis spectroscopy.51... 

Reaction of -dimethylthiobenzene sulfoxide 56 with trifluoroacetic anhydride results in a mixture of sulfide 65 and the corresponding mono- and disubstituted products of the Pummerer rearrangement 63, 64 via intermediate disulfonium dication 62 (Scheme 23).88... 

Thus a number of enzymes have been shown to be able to control the oxidation of sulfides to optically active sulfoxides most extensive investigations have concentrated on mono-oxygenases (e.g. from Acinetobacter sp., Pseudomonas putida) and haloperoxidases1 071 (from Caldariomyces fumago and Coral I ina officinalis). A comparison of the methodologies11081 led to the conclusion that the haloperoxidase method was more convenient since the catalysts are more readily available (from enzyme suppliers), the oxidant (H2O2) is cheap and no cofactor recycling is necessary with the haloperoxidases. Typical examples of haloperoxidase-catalysed reactions are described in Scheme 24. 

Recently, much attention has been devoted to the use of car-banions derived from optically active a-substituted sulfoxides in asymmetric synthesis. Thus, the condensation of the lithium salt of the optically active dithioacetal mono-5-oxide 51 with benzaldehyde yields a mixture of diastereomeric adducts 307, which were converted in high chemical yield into the corresponding optically active a-methoxyaldehyde 308, having 70% optical purity (316). 

Quite recently, the addition of methoxy anion to the optically active styryl sulfoxide 314 was found to give a mixture of diastereo-meric dithioacetal mono-iS-oxides 315, which were converted to the optically active a-methoxy aldehyde 316, having 59.6% optical purity (316). 

Methyl vinyl ketone, see 2-Methyl-l, 3-butadiene Molinate sulfoxide, see Molinate Monobutyl phosphate, see Tributyl phosphate Monobutyl phthalate, see Benzyl butyl phthalate Mono-n-butyl phthalate, see Di-n-butyl phthalate Monobutyl phthalate, see Di-n-butyl phthalate Monochlorobenzidine, see 3,3 -Dichlorobenzidine Monochlorobiphenyl, see Chlorobenzene, PCB-1221, PCB-1254... 

Electrophilic substitution of thianthrene takes place at C-2. No examples of even minor amounts of 1-mono-substituted product have been reported. Disubstitution gives 2,7- (usually) or 2,8-products. In a few cases, 2,6-derivatives have been claimed. The presence of a sulfoxide or sulfone unit greatly reduces the susceptibility of either ring to electrophilic substitution. Carbon-centered electrophilic addition to sulfur to produce 5-R-thianthrenium salts has been described rarely most examples of the formation of such salts have involved the thianthrene radical ion(l-t-). Treatment of thianthrene with alkyl/aryllithiums produces the 1-lithio-species, and these organometallic derivatives allow the introduction of substituents at this position. 

Balance of Activatlon/DetoxifIcatlon Reactions. The activated intermediates or reactive fragments appear to be carbamoyl sulfoxides or mono-, dl- and trlchloroacroleins, all of which are relatively unstable compounds. The carbamoyl sulfoxides are rapidly detoxified by reaction with GSH, involving catalysis by a GSH -transferase in the case of -alkyl and -benzyl thiocarba-mate sulfoxides ( -5, 24) but probably not with -chloro-... 

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