Sulfoxide, methyl methylthio

Die Synthese von racemischen a-Acylamino-carbonsaure-methylestern VI aus ali-phatischen Carbonsaure-nitrilen I und dem Carbanion von Methyl-(methylthio-methyl)-sulfoxid II verlauft iiber ein Enamino-sulfoxid III. Dieses lagert sich bei der N-Acylierung mit Carbonsaure-anhydriden/Pyridin in die Aminosaure-Derivate IV mn, die iiber die a-Acylamino-a-methylthio-carbonsaure-methylester V in die a-Acylamino-carbonsaure-methylester VI iibergefiihrt werden konnen1 ... 

Thiophene-2-carbaldehyde condenses easily with ethyl acetoacetate or ethyl nitroacetate in the presence of TiCU and a tertiary organic base (pyridine or N- methylmorpholine) at 0-22 °C, giving (361) (72T663). Base-catalyzed condensation of thiophene-2-carbaldehyde with methyl (methylthio)methyl sulfoxide followed by treatment with HC1 in alcohols gives (2-thienyl)acetic esters (Scheme 114) (79BCJ2013). 

Sulfoxid Methyl-(4-methylthio-phenyl)- Ell, 747 (S-Oxigenier.) 4H,6H-[Pg.494]

Sulfoxid Methyl-(l-methylthio-2-oxo-2-phenyl-ethyl)- Ell, 790 (x-Acylier.)... 

In conclusion, the 1,3-dithiane unit still remains among the most valuable acyl anion equivalents, although that involving methyl methylthio sulfoxide or its diethyl analog offers the definite advantages of proceeding with metal hydride or even under phase-transfer catalysis conditions and of producing the carbonyl compound under reasonably mild conditions. 

Als Synthesebausteinc fiir die Aldehyd-Herstellung (Ubersicht s. Lit.360) haben Methyl-(methylthio-methyl)-(V)360"362, Ethyl-ethylthiomethyl-sulfoxid(VI)295,363,364 bzw. l,3-Dithian-S-oxid(VII)295,364-366 Anwendung gefunden. 

ALDEHYDES Lithium methylthio-formaldine. 2-(N-Methyl-N-formyl)-aminopyrldine. Methyl methylthio sulfoxide. 2-Methylthio-l, 4-diphenyl-... 

Related Reagents. Methyl Iodide Methyl Sulfate 1-Benzene-sulfinyl Piperidine Diphenyl Sulfoxide Dimethyl(methylthio) Sulfonium Tetrafluoroborate. 

The alkylthio group is replaceable by nucleophiles. The positions 7 and 4 react under mild conditions in that order the 2-alkylthio functions require more drastic treatment. Conversion of l-methyl-4-methylthiopteridin-2-one (157) into the 4-methylamino derivative (158) can be achieved by stirring with methylamine at room temperature (equation 48). The reactivity of an alkylthio group can often be further enhanced by oxidation to the corresponding sulfoxide and sulfone. Thus, reaction of l,3-dimethyl-7-methylthiolumazine (160) with m-chloroperbenzoic acid yields 7-methylsulfinyl- (161) and 7-methylsulfonyl-l,3-dimethyllumazine (162 equation 49) (82UP21601). 4-Amino-2-methylthio-7-... 

Treatment of ethyl 10-methylthio-9-fluoro-3-methyl-2,3-dihydro-7-oxo-7//-pyrido[l,2,3- 7e]-l,4-benzoxazine-6-carboxylate with oxone in aqueous MeOH at 0°C afforded 10-methylsulfonyl derivative (99H(51)1563). Methylthio group in a 7-(4-methylthiophenyl)-5-oxo-2,3-dihydro-5//-pyrido[l,2,3- 7e]-l,4-benzoxazine-3-carboxamide was oxidized to a sulfoxide and a sulfone group (OOMIPl). 

Scheme 5.1 Mechanism of thioglycoside activation (a) by thiophiles X1 such as /V-bromosuccinimicle (NBS), 11,12 methyl triflate,13 dimethyl(methylthio)sulfonium triflate (DMTST),14 phenylselenyl triflate (PhSeOTf),17,18 iV-iodosuccinimide/triflic acid (MS/TfOH),19 20 and iodonium di-sym-collidine perchlorate (IDCP)21 (b) by tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBPA,+)25 and (c) via anomeric sulfoxides.26 The stereochemical outcome of these glycosylations follows the same general trends as with many other glycosyl donor/promoter combinations (m-CPBA = mcta-chloroperbenzoic acid).

Oxidation of 2-methyl-3-(methylthio)quinoxaline 1,4-dioxide with 1 equivalent of m-chloroperbenzoic acid yields the corresponding sulfoxide, and 2 equivalents of oxidizing agent gives the sulfone, both products being isolated in good yield. Treatment of the substituted sulfoxide- or sulfone-quinoxaline dioxides with aqueous halogen acids leads to nucleophilic displacement and the formation of 2-haloquinoxaline 1,4-dioxides.199... 

Methyl 3-oxodithioalkanoates 109 Methyl 2-pyridinesulfinate 55 (Methylthio)furans 146 (/ )-(+)-MethyI p-tolyl sulfoxide 26 Michael addition... 

Monomolar benzylation of methyl 2,3-di-0-benzyl-a-D-galactopyranoside in DMF gave 2,3,6-tri-O-benzyl derivative in 73% yield [52], The primary 6-benzyl ether also forms the major part of the monobenzyl fraction obtained from methyl a-D-galactopyranoside or from its p-anomer [53]. Interestingly, position 6 becomes less reactive than position 2 if 3,4-0-isopropylidene acetals is used to protect the other two secondary hydroxyl groups. The ratio of 2- and 6-benzyl ethers was found to be 11 1 in the a-anomer and 2.5 1 in the p-anomer [53] (see also, Ref. [54]). Uridine [55], cyti-dine [56], and 4-(methylthio)uridine [56] also prefer OH-2 over the primary position when benzylated in dimethyl sulfoxide (for other benzylations in this solvent, see Refs. [35, 57]). 

Methyl-l-penten-3-one-l-ol 1 and glacial acetic acid in benzene was added to pyrrolidine to give 2-methyl-l-pen ten-1-[N-pyrrolidinyl]-3-one 2. Compound 2 when treated with oxalyl chloride and methanol was added, 3,5-dimethyl-2-methoxycarbonyl-4-pyrone 3 was produced. Treatment of compound 3 with sodium borohydride in methanol gives 3,5-dimethyl-2-hydroxymethyl-4-pyrone 4. Compound 4 was converted to 3,5-dimethyl-2-hydroxymethyl-4-pyridone 5 by heating compound 4 with aqueous ammonia in a sealed flask. Compound 5 was converted to 4-chloro-2-chloromethyl-3,5-dimethyl pyridine 6 by treatment with phosphorous oxychloride. Treatment of compound 6 with 5-methoxy-2-mer-captobenzimidazole in tetrahydrofuran gave 2-[2-(4-chloro-3,5-dimethyl pyridinyl)methylthio]-5-methoxy benzimidazole 7. When compound 7 was treated with potassium hydroxide in dimethyl sulfoxide containing methanol, 2-[2-(3,5-dimethyl-4-methoxypyridinyl)methylthio]-5-methoxy... 

In comparison to some of the other activation methods however, the dimethyl sulfoxide-acetic anhydride procedure has certain disadvantages. The method often requires the use of long reaction times (1 24 h), which can result in many side reactions, especially with sensitive substrates. Notable in this respect is that it is not uncommon for this procedure to result in the formation of substantial yields of the thiomethyl ethers obtained from the Pummerer rearrangement product as described above. In fact upon attempted oxidation of cholesterol with this system, the major product obtained was the corresponding (methylthio)methyl ether. Acetates may also be formed if the alcohol is unhindered. For example the sugar derivative (9) reacts under these conditions to form an enol acetate (derived from the requir carbonyl compound) in 40% yield contaminated with 30% of the acetate (10 equation S). ... 

Sulfoxid [2-(3,4-Methylendioxy-phenyl)- -methylthio-2-oxo-ethyl]-methyl- Ell, 790 (Michael-Add.)... 

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