Sulfoxide intermediate

The enantioenriched sulfoxide intermediate 72 (R = CH2OH), obtained by asymmetric 5-oxidation with a chiral oxaziridine (89 11 enantiomeric ratio), has provided a highly enantioselective synthesis of the benzothiepin derivative 71 (4R, 5R). The aldehyde intermediate 72 (R = CHO) was cyclized asymmetrically to 71 (4R, 5R) with >98 2 enantiomeric ratio. Base treatment (f-BuOK, -10°C, THF) of the racemic benzothiepin 73... 

It is also possible to intercept the chiral sulfoxide intermediate and convert this species to an a-amino ester. Thus, the Grignard addition to dihydro-l,2-thiazine 1-oxides 131a and 131b followed by NH4CI workup and subsequent ozonolysis of 132a and 132b affords amino ester 133 with excellent retention of the absolute stereochemistry (Scheme 17) <2004JOC7198>. 

The second nonconjugative pathway is dethiomethylation, which results in diketo metribuzin (DK) [4-amino-6-(l,l-dimethylethyl)-l, 2,4-(2//,4//)-dione], as shown in Figure 7.13. This process was observed by Schumacher (1974) Mangeot et al. (1979) Abusteit et al. (1985) Gawronski et al. (1986,1987) and Devlin el al. (1987). The dethiomethylation may proceed through an oxidative pathway via a sulfoxide intermediate, as reported in mice and rats (Saeman and Casida, 1984 Saeman et al., 1985). 

The enantioselective sulfoxidation of thioanisole for the (R)-isomer by H64D/V68A and H64D/V68S Mbs suggest the sulfoxidation intermediate shown in Scheme 9 could be stabler for (R)-sulfoxide formation over the (S)-isomer. The chiral discrimination for (R)- and ( -intermediates is caused by steric interaction between the transition state and the heme cavity. However, it is... 

Figure 13. Schematic comparison of sulfoxidation intermediates and amines bound to the heme.

Activation temperatures of about -60 C are typically used to form the activated dimethyl sulfoxide intermediate (19), which arises by spontaneous loss of carbon dioxide and carbon monoxide from an initially form salt (Scheme 6). 

In the stereoselective total synthesis of ( )-14-deoxyisoamijiol by G. Majetich et al., the last step was the epimerization of the C2 secondary allylic alcohol functionality. The Mitsunobu reaction resulted only in a poor yield (30%) of the inverted product, so the well-established sulfoxide-sulfenate rearrangement was utilized. The allyic alcohol was first treated with benzenesulfenyl chloride, which afforded the thermodynamically more stable epimeric sulfenate ester via an allylic sulfoxide intermediate. The addition of trimethyl phosphite shifted the equilibrium to the right by consuming the desired epimeric sulfenate ester and produced the natural product. 

This methodology was employed for the synthesis of the reported structure of the alkaloid jamtine (02OL715, 02JOC929). The key sulfoxide intermediate 307 was heated with CSA to produce several tricyclic products (98% yield) as a mixture (5 2 1 1) of diastereomers in which 308 predominated (Scheme 57). The stereochemistry of 308 was secured by X-ray crystallographic analysis and is consistent with a Nazarov-type conrotatory 47i-electrocyclization followed by attack of the nucleophilically disposed aromatic ring from the least hindered side of the intermediate iminium ion. Reaction of a-ethylthio amide 308 with NaH effected an intramolecular alkylation to provide tetracycle 309. 

Sulfide Oxidation (Merck). A process for a chiral sulfoxide intermediate was developed using Kagan s Ti/tartrate and applied on a multikilogram scale for... 

Synthesis of ( )-j8-(Benzylo3gf)slyrenes from Ben l Alcohols. ( )-/3-(Benzyloxy)styrenes (7) were obtained from the reaction of benzyl alcohols (6) with KOH/DMSO (eq 5) in 56-92% yields. This result was explained by an initial oxidation to the benzaldehyde followed by a condensation with DMSO anion to form intermediate (8). Subsequent addition of benzyloxide anion to (8) and elimination of MeSO gives the product (7). The incorporation of the DMSO carbon was confirmed by and labelling. The methyl styryl sulfoxide intermediate (8) was independently synthesized and converted into (7) under identical reaction conditions. ... 

Sulfides are readily oxidized to sulfones, a transformation proceeding through a sulfoxide intermediate. For example, oxidation of dimethyl sulfide first gives dimethyl sulfoxide (DMSO), which subsequently furnishes dimethyl sulfone. Dimethyl sulfoxide has already been mentioned as a highly polar nonprotic solvent of great use in organic chemistry, particularly in nucleophilic substitutions (see Section 6-8 and Table 6-5). 

Oxidation of EDOT by m-chloroperbenzoic acid (m-CPBA) in halogenated hydrocarbons results in mixtures of the EEXTT-derived sulfone (via sulfoxide intermediate) and the thiolactone heterocyclus 3,4-ethylenedioxy-2(5H)-thiophenone (Figure 5.24). 

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