DMSO oxidation with

The best direct synthetic route to uracil is probably the classical procedure from malic acid and urea in concentrated sulfuric acid (26JA2379), despite efforts to use maleic acid, urea and polyphosphoric acid (71S154) or propiolic acid, urea and a little concentrated sulfuric acid (77JOC2185) to achieve the same result. However, the most convenient source (apart from purchase) is to convert 2-thiouracil (937 X = S) into uracil by boiling with aqueous chloroacetic acid (52MI21300) or perhaps by oxidation with DMSO in strong sulfuric acid (74S491). 

As discussed in Section 8.2.1, DMSO reacts with Me3SiCl 14 in acetonitrile, via 789 and 1276, to give 1277 and HMDSO 7, which separates as a mobile colorless upper layer [70]. One thus wonders whether the reaction conditions for oxidations with DMSO/MesSiCl 14, DMSO/Me2SiCl2 48, or DMSO/SiCU 57 can be adapted to generate Me2SCl2 1277 cleanly in acetonitrile or CH2CI2 for in-situ or subsequent oxidation of primary or secondary alcohols to their carbonyl compounds, before decomposition of 1277 occurs to MeSCl 1278 and MeCl. 

Some studies have focused on the generation of the corresponding radical cations of methylamine, dimethylamine and TV-methylpiperidine2,3 by /-irradiation at low temperature. The radical cation of t-BuNH2 can be formed (k = 3.4 x 106 M-1 s 1) by oxidation with DMSO-C14. 

Conversion of the 2-buten-4-olides (197 R = Me) into the bromomethyl derivative (197 R = CH2Br), followed by oxidation with DMSO, leads to the dioxo compounds (198) (Equation (68)) <84KGS740>. 

The synthesis of (+)-nojirimycin (1) from tetra-O-benzyl-D-glucopyranose (11) as depicted in Scheme 10 °° was found to be unreliable. Compound 11 underwent anomeric oxidation with DMSO-AC2O to afford tetra-0-benzyl-D-glncono-l,5-lactone (52) in 84% yield, which was treated with liquid ammonia solntion in the presence of trace amounts of Amberlite IR-120 (H+) resin in dioxane to give the glnconolactam 53 (50%). Treatment of 53 with sodinm borohydride followed by removal of the benzyl protecting groups afforded... 

The most difficult total syntheses in this class of pseudotrisaccharides were those of streptomycin and dihydrostreptomycin. About 35 years after their discovery and the elucidation of their structure, S. Umezawa and colleaguessucceeded in synthesising these compounds. The glycosyl derivative (I), prepared through several steps from streptobiosaminide, was condensed with the protected streptidine (II), to yield dihydrostreptomycin, after deprotection. Subsequent oxidation with DMSO/dicyclo-hexylcarbodiimide (DCC) produced streptomycin... 

Another useful method for modification of tryptophan groups is oxidation with DMSO and cone. HCI to form oxindole (2-hydroxytryptophan) groups. This reaction proceeds in >95% yield. ... 

Oxidations. Dimethyl selenoxide is more effective than dimethyl sulfoxide (4,194 6, 227) for oxidation of trivalent phosphorus and thiocarbonyl compounds. It oxidizes acyclic P(III) compounds to oxides (with nearly complete inversion of configuration) cyclic P(III) compounds are oxidized with retention of configuration. The same stereochemical result obtains in oxidations with DMSO. 

Swern oxidation of various indolic substrates has been described, and a range of products resulting from overall oxidation at the 2-position have been observed. For example, indolylpropanol 1809 [R = (CH2)30Hj is oxidized with DMSO and either trifluoroacelic anhydride or oxalyl chloride to give the unsaturated aldehyde 1810 [R = (CH2)2CH0] [1333]. 

Tomita R, Yasu Y, Koike T, Akita M (2014) Cranbining photoredox-catalyzed trilluoro-methylation and oxidation with DMSO facile synthesis of a-trifluoromethylated ketones from aromatic alkenes. Angew Chem Int Ed 53 7144—7148. doi 10.1002/anie.20I403590... 

Preparation of PEG aldehyde proved problematic primarily because of the pronounced ability of PEG to form complexes with metallic oxidizing agents. An initial preparation with pyridinium chloro-chromate gave aldehyde product, which could be purified with variable success, by chromatography on alumina. Oxidation with DMSO-acetic anhydride and substitution on the diethyl acetal of bromoacetaldehyde (eq. 8) provided two excellent methods for preparation of the PEG aldehyde. 

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