Moffatt-type oxidation

Oxidation. The reagent has been used in place of DCC in Pfitzner-Moffatt type oxidations (I, 304-307 2, 162). Thus 2, 3 -0-isopropylideneadenosine (2) was oxidized to 2, 3 -0-isopropylideneadenosine-5 -aldehyde (3) in 60% yield by the ketenimine (1), DMSO, and phosphoric acid. 

Moffatt-type oxidation of the resulting carbinol to the aldehyde and Wittig reaction with l-tributylphosphoranylideneheptan-2-one led to the enone (XLVII). Borohydride reduction, removal of the tetrahydropyranyl group and ester hydrolysis then gave (+ )-PGEi methoxime. 

These reagents have a number of drawbacks. First of all, they are toxic especially via contact with skin. The LD50 (dermal, rat) of DCC is 71 mg kg. This should always be considered if the reaction is used for the preparation of materials for biological applications. Moreover, the N.N -dialkylurea formed during the reaction is hard to remove from the polymer except for preparation in DMF and DMSO, where it can be filtered off. In case of esterification of polysaccharides in DMSO in the presence of these reagents, oxidation of hydroxyl functions may occur due to a Moffatt type reaction (Fig. 25, [188]). The oxidation products formed can be detected with the aid of 2,4-dinitrophenylhydrazine, e.g. in case of the conversion of dextran with DCC in DMSO [189],... 

Microflow systems serve as effective environments to perform various oxidation reactions using chemical reagents. The oxidation using dimethyl sulfoxide (DMSO), which is known as Moffatt-Swern type oxidation, is one of the most versatile and reliable methods for the oxidation of alcohols into carbonyl compounds in laboratory synthesis [1, 2]. However, it is well known that activation of DMSO leads to an inevitable side-reaction, Pummerer rearrangement, at temperatures above — 30°C (Scheme 7.1). Therefore, the reaction is usually carried out at low temperatures (—50 °C or below), where such a side-reaction is very slow [3, 4]. However, the requirement for such low temperatures causes severe limitations in the industrial use of this highly useful reaction. The use of microflow systems solves the problem. For example, the oxidation of cyclohexanol can be accomplished using a microflow... 

The first total synthesis of the nucleoside antibiotic herbicidin B was accomplished in the laboratory of A. Matsuda. The key step was a novel aldol-type C-glycosidation reaction promoted by Sml2 between a 1-phenylthio-2-ulose derivative and a 1- 3-D-xylosyladenine-5 -aldehyde derivative. During the preparation of the phenylthio sugar subunit, the Moffatt oxidation was applied to convert the primary alcohol to the corresponding aldehyde, which was immediately oxidized with PDC in DMF/MeOH to the methyl ester. The reaction conditions were completely compatible with the silyl protecting group as well as the thioacetal functionality. 

The total synthesis of the antimicrobial drimane-type sesquiterpene (-)-pereniporin A was achieved by the research team of K. Mori. The advanced intermediate bicyclic primary alcohol was first oxidized to the corresponding aldehyde using the Moffatt oxidation. Interestingly, the sensitive a-hydroxy aldehyde moiety in the product remained unchanged. The final step was a global deprotection followed by a spontaneous lactol formation. 

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