I₂- or NBS-Catalyzed Highly Efficient α-Hydroxylation of Ketones with Dimethyl Sulfoxide

Abstract

An efficient method for the direct preparation of high synthetic valuable α-hydroxycarbonyls is described. The simple and readily available I2 or NBS was used as catalyst. DMSO acts as the oxidant, oxygen source, and solvent. A diverse range of tertiary Csp(3)-H bonds as well as more challenging secondary Csp(3)-H bonds could be hydroxylated in this transformation. The reaction is mild, less toxic and easy to perform.

Bromine-Mediated Cross-Dehydrogenative Coupling (CDC) Reactions

“…A substitution reaction of α-haloketone A with DMSO generates the ion-pair intermediate B, which subsequently gives intermediate C. The final product is obtained through protonation and S-O bond cleavage of intermediate C.In this way, the halide catalysts are regenerated 10. …”

C−O coupling of Malonyl Peroxides with Enol Ethers via [5+2] Cycloaddition: Non‐Rubottom Oxidation

“…In a number of studies direct hydroxylation of ketones [36] was achieved by using hypervalent iodine compounds, [37] molecular oxygen, [38] [39] DMSO/I 2 or DMSO/NBS, [40] DMSO/CuBr 2 or DMSO/HBr, [41] thallium(III)/p-nitrobenzenesulfonate, [42] Ti(O i Pr) 4 / TBHP [43] and PhNO/TFA. [44] In regard to the oxyfunctionalization of carbonyl targets, [45] they were previously limited to the alkoxy, [46] peroxy, [47] oxygensulfonyl, [48] oxygen-phosphoryl, [49] aminoxy [50] groups.…”

Iodine‐Mediated Nucleophilic Direct Oxidative α‐Acetoxylation and α‐Alkoxylation of Ketones

“…The direct α‐oxygenation of carbonyl compound includes oxidation of enol or its derivatives with peroxides such as m ‐CPBA, TBHP, benzoyl peroxide and oxone . In few reports the DMF and DMSO were used as oxygen sources.The α‐acyloxy carbonyl compounds were also synthesized from ethynylcarbinols, terminal alkynes and enamides . Although, various procedures have been reported for the synthesis of α‐acetyloxy motifs, the development of a general and facile strategy is highly desirable due to the disadvantages like harsh reaction conditions, metal catalyzed conditions, multistep synthesis, acidic conditions and multiple oxidation procedures associated with them.…”