#Dimethyl sulfide charge Activator

Addition of the primary or secondary alcohol followed by deprotonation of sulfenate 25 with triethylamine leads to the desired aldehyde or ketone, respectively.Dimethyl sulfoxide (DMSO) has been known to enhance cell membrane permeability of drugs or DNA. Dimethyl sulfoxide, which is at the same oxidation level as salt 24, reacts with oxalyl chloride ( 23) to liberate carbon monoxide, carbon dioxide and reagent 24. Swern Oxidation: (1978) This later Swern procedure is a convenient method for the production of reagent 24 without using dimethyl sulfide and chlorine. The ketone or aldehyde is produced in the usual fashion with triethylamine. Addition of the alcohol to intermediate 21 yields the desired sulfenate 22. Swern Oxidation: (1976) This early Swern oxidation employs trifluoroacetic anhydride ( 20) at -50 oC to activate dimethyl sulfoxide. The usual sulfenate intermediate 18 collapses by the intramolecular mechanism upon the addition of triethylamine. In the reaction of this species with an alcohol, the succinimidyl group functions as a leaving group. Sulfenate 15 is decomposed by the intramolecular mechanism (vide supra) to yield an aldehyde or ketone.Ĭorey-Kim Oxidation: (1972) In this procedure dimethyl sulfide is activated (oxidized) with N-chlorosuccinimide ( 16) to provide reagent 17. Sulfate is the leaving group in the displacement by the alcohol (primary or secondary) in intermediate 14.

#Dimethyl sulfide charge Activator

Parikh-Doering Oxidation: (1967) This oxidation utilizes the pyridine sulfur trioxide complex ( 13) as the activator of dimethyl sulfoxide. Accordingly, the reaction produced dimethyl sulfide-d 5( 12) and undeuterated aldehyde 11 (Experiment 2). To corroborate this mechanism the deuterium was incorporated into DMSO as DMSO-d 6. The ylid decomposes by intramolecular deprotonation to produce the observed products. This result is consistent with a base that deprotonates the methyl group attached to sulfur forming ylid 6. However, dimethyl sulfide-d 1 ( 7) was obtained. If the Kornblum mechanism were to apply, the dimethyl sulfide obtained would be devoid of deuterium (Experiment 1). Sulfenate salt 5 was prepared by the Moffatt-Pfitzner procedure (see above). The elimination is an intramolecular process. Torrsell Mechanism: (1966) The Swedish chemist Torrsell demonstrated that the mechanism of these DMSO-based oxidations do not proceed via an intermolecular β-elimination. It is critical that the conjugate base of the acid is basic enough to effect the last step of the reaction.

However, pyridinium trifluoroacetate is an effective catalyst. Although phosphoric acid is an effective acid catalyst for this reaction, sulfuric acid, hydrogen chloride and trifluoroacetic acid are not. This species suffers collapse to the carbonyl compound under the influence of the dihydrogenphosphate anion. Stable dicyclohexyl urea 4 is formed along with sulfenate salt 3. Intermediate 2 is again protonated to facilitate addition of the alcohol oxygen on the sulfur atom. The activator is prepared by protonation of dicyclohexyl carbodiimide ( 1, DCC), which is attacked by dimethyl sulfoxide. Moffatt-Pfitzner Oxidation: (1963) This variant of a dimethyl sulfoxide-based oxidation was developed at Syntex. Moreover, the chloroformate is readily available by treatment of the alcohol to be oxidized with excess phosgene. This procedure ameliorated the harsh conditions of the Kornblum procedure. Addition of triethylamine generates the oxidation product. The essential issue is to find a method to generate the sulfenate salt.īarton Modification: (1964) Barton and coworkers were able to generate sulfenate salts by treating alkyl chloroformates with DMSO with loss of CO 2. The downside of the procedure is the elevated temperature although the contact time is only a few minutes. Presumably the tosylate can be prepared from the alcohol which is a more direct route. This work formed the tosylate from the alkyl iodide with silver tosylate.

Dimethyl sulfide (DMS) is the reduction product of the reaction. The accepted mechanism at the time was an E2 elimination as shown. Kornblum Oxidation: (1959) A primary tosylate is heated at 150 o to cause S N2 displacement by the oxygen of dimethyl sulfoxide (DMSO) in the presence of NaHCO 3.