Dimethylsulfoxide-Acetic anhydride

A variety of methods have been described to solve the task in solution.16 Common oxidative agents for this transformation include various heavy-metal reagents such as chromium-or ruthenium-based oxides, pyri-dine-S03, and dimethylsulfoxide (DMSO) in combination with acetic anhydride, carbodiimide, or oxalyl chloride for activation. One of the most prominent methods for the reliable conversion of sensitive compounds is the Dess-Martin reagent or its nonacetylated equivalent, 1-hydroxy-(17/)-benzo-l,2-iodoxol-3-one-l-oxide (2-iodoxybenzoic acid, IBX). 

Scheme 6 describes the most important reactions of the perimidinespirocyclo-hexadienone 1. A treatment of 1 (R = H) in dimethylsulfoxide (DMSO) solution with methyl iodide in the presence of potassium carbonate affords the A-m ethyl derivative la (R = Me), whereas use of an excessive amount of methyl iodide in this reaction leads to the A,A -dimethyl derivative of the ring-closed tautomer.4,7 By contrast, acylation of la by acetic anhydride or its tosylation by treatment with p-toluenesulfonyl chloride results in the formation of the respective derivatives of the ring-opened tautomeric form lb. 

Protocol 4 describes the oxidation of alcohol 8 by dimethylsulfoxide (DMSO) and acetic anhydride at room temperature.20 This Albright-Goldman method is more economical and simpler to perform on a large scale than other... 

The methylthiomethyl ether (MTMOR) Tertiary hydroxyl groups, which are susceptible to acid-catalyzed dehydration, can be easily protected as MTM ethers and recovered in good yield. The MTM ether of a hydroxyl group can be formed either by a typical Williamson ether synthesis or on reaction with dimethylsulfoxide (DMSO) and acetic anhydride (AC2O). In the latter case, the reaction proceeds with the Pummerer rearrangement " (Scheme 1.25). 

Dimethyl sulfoxide-Acetic anhydride, 199 Dimethylsulfoxide-N-Bromosuccinimide, 199-200... 

Appropriate alkyl iodides or bromides were reacted with 57 and 2-epi-Sl in the presence of Ag20 in CH3CN with yields ranging from 36 to 77% (74, Scheme 10) [34, 51]. However, with these conditions preparation of branched alkyl ethers was unsuccessful [51]. Reacting 57 with chloromethyl methyl ether, diisopropylethy-lamine, and catalytic DMAP in CH2CI2 afforded 75 in a 72% yield and was the first 1 derivative reported to have increased affinity at the KOP receptor relative to 1. [41, 52]. Based on the successful increase in affinity of derivative 75, additional simple alkoxymethyl ethers were obtained using appropriate alkyoxymethyl chloride with diisopropylethylamine in DMF (76-78). However, more complex alkoxymethyl derivatives were synthesized from the common methylthiomethyl ether intermediate (79), which was obtained from reaction of 57 with acetic acid, acetic anhydride, and dimethylsulfoxide (DMSO) [52]. Compound 79 was then... 

The introduction of a nitro group at C-1 in isoquinolines can be achieved using a mixture of potassium nitrite, dimethylsulfoxide and acetic anhydride. The key step is the nucleophihc addition of nitrite to the heterocycle previously quatemised by reaction at nitrogen with a complex of dimethylsulfoxide and the anhydride. 

Otto reported (71AP505) (Scheme 72) that pyrazol-3-one 62 reacts at ambient temperature with thiophenol in dimethylsulfoxide to afford 4-phenylthiopyrazol-3-one 227 in 81% yield. It is interesting that sulfonium ylid 226 was the proposed intermediate since it could be formed by reacting pyrazol-3-one 62 with acetic anhydride in dimethylsulfoxide and could then be converted into product 226 by reacting with thiophenol in 7V,7V-dimethylformamide and a catalytic amount of 4-toluenesulfonic acid. 

Inoue, S., Omoto, S., Iwamatsu, K., and Niida, T. (1980). Modification of macrolide antibiotic midecamycin. II. Reaction of midecamycin and 9-acetyl midecamycin with dimethylsulfoxide and acetic anhydride. J. Anibiot. 33,61-71. 

Diethylenetriamine pentaacetic acid (DTPA) 97% purity, ethylenediamine and carbonyldiimidazole were purchased from Aldrich and used as supplied. Acetic anhydride, pyridine, dimethylsulfoxide and dimethylformamide, also from Aldrich, were of Analar purity, and were dried over molecular sieves 3A before use. Dextran (MW 40000), di-t-butyl dicarbonate of 97% purity and Dowex 50Wx8x200 ion exchange resin, were supplied by Sigma. 

Diacetone allose can be formed from diacetone glucose by first oxidizing die C-3 hydroxyl carbon with acetic anhydride in dimethylsulfoxide [101], followed by reduction with sodium borohydride (reaction 4.95). The reduction forms exclusively the allose configuration. 

Solvents A acetone, AA acetic acid anhydride, ACN acetonitrile, AcOH glacial acetic acid. Butac butyl acetate, Bu 1-butanol, GHT butylhydroxy-toluene, Ch chloroform, CY cyclohexane, Dh dichloromethane, De 1,2-dichloroethane. DIMSO. dimethylsulfoxide, DO dioxane, E diethyl ether, Et ethanol. Etac ethyl acetate, F formamide, H hexane. He heptane, IP isopropanol. Me methanol, MEK methyl ethyl ketone, P petroleum ether,. Py pyridine, T toluene, W water, X xylene. 

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