Benzyl sulfoxide

A filtered solution of 30 g. (0.14 mole) of benzyl sulfide (p. 32) in 250 ml. of acetone is treated with 15 g. of 30% hydrogen peroxide, and the mixture is shaken thoroughly. After standing at room temperature for 48 hours, the acetone is allowed to evaporate. The residue is recrystallized from petroleum ether to give 22 g. (75% yield) of white crystalline solid, melting at 132-133°. 

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A salt effect similar to that reported for the deuteration of methyl benzyl sulfoxide (see Section D. 1.1.1.5.) was also shown in this case (Table 2). 

Accordingly, there have been numerous studies on the stereochemistry of these a-sulfinyl carbanions56-77. Representative data on the reactions of a-lithiosulfoxides derived from benzyl sulfoxides with some electrophiles are listed in Table 13. Although the stereochemistry depends on the substituent on the sulfinyl function, the diastereomeric ratio remains the same regardless of the electrophile used for each sulfoxide. 

One interesting observation deduced from the data of Table 13 is that, despite the same diastereomeric ratio, the absolute configuration around the carbon atom of the major diastereomer changed with the electrophile used. In other words, the reactions of a-lithiobenzyl sulfoxides with 020 - and its carbonylation and carbonation proceeded with retention of configuration, while methylation with CHjl resulted in inversion . The stereochemical study of these reactions was conducted with optically active benzyl sulfoxides 42 and 39 as shown in Scheme i - - nd an interesting... 

The relative ease with which aryl benzyl sulfoxides undergo homolytic dissociation (Rayner et al., 1966) as compared to aryl benzyl sulfides or sulfones is supportive of this idea that ArSO radicals are easier to form than ArS or ArS02 radicals. Another interesting set of observations is the following. Booms and Cram (1972) found that optically active arene-sulfinamides ArS(0)NRPh (R = H or CH3) racemize thermally very readily at room temperature and that this racemization is the result of a free radical chain reaction (160) that is initiated by the dissociation of some of the sulfinamide into an ArSO and a PhNR radical (159). While the length of the inhibition... 

A different approach to the resolution of sulfoxides was recently reported by MikcJajczyk and Drabowicz (35). It takes advantage of the fact that sulfoxides as well as other sulfinyl compounds ry easily form inclusion complexes with 3-cyclodextrin. Since -cycl dextrin (the host) is chiral, its inclusion complexes with racemic guest substances are mixtures of diastereomeis that can be formed in unequal amounts. In this way a series of alkyl phenyl, alkyl p-tolyl, and alkyl benzyl sulfoxides has been resolved. However, the optical... 

In contrast to asymmetric oxidation of unsymmetrical sulfides with chiral peracids, microbial oxidation usually gives much better results. Thus, optically active phenyl benzyl sulfoxide was prepared by oxidation of the parent sulfide via fermentation with Aspergillus niger, NRRL 337, with 18% optical purity (42). Similarly, asymmetric... 

Bromination of (-)-(5 )-benzyl methyl sulfoxide 34 with bromine in pyridine affords a mixture of two regioisomers a-bromomethyl benzyl sulfoxide 328 and a-bromobenzyl methyl sulfoxide 329, in a molar ratio of 3 2 (325). Oxidation of thp latter gives the corresponding sulfone (-)-(S)-330, the absolute configuration of which was determined by X-ray analysis. In this context, it is interesting to point out that the formation of the sulfoxide 328 is accompanied by retention at sulfur, whereas 329 is formed with inversion at sulfur. 

A rare case of asymmetric induction caused by isotopic substitution was observed (326) when optically active (+)-() )-a,a-dideuteriodi-benzyl sulfoxide 331 was chlorinated with dichloroiodobenzene in pyridine, a,a-Dideuteriobenzyl a -chlorobenzyl sulfoxide 332 was obtained as a major regioisomer with at least 78% isotopic purity. The high stereospecificity of the reaction is indicated by formation of essentially only one of the possible diastereomers. Oxidation of sulfoxide 332 affords the sulfone 334, which has high optical rotation. 

In the similar reaction of 2-pyridyi benzylic sulfoxides with benzylic Grignard reagents, the incoming benzylic group seemed to couple pref-... 

KINETIC RESOLUTION OF RACEMIC SULEOXIDES (FIGURE 9.4) 9.3.2 SYNTHESIS OE (R)-(+)-PHENYL BENZYL SULFOXIDE... 

The crude reaction mixture was purihed by column chromatography by using petroleum ether EtOAc (6 2-5 5) as eluent to afford (7 )-(+)-phenyl benzyl sulfoxide (0.067 g, 31 %), phenyl benzyl sulfone (0.132g, 57 %) as well as (DHQD)2-PYR (0.085 g). Recovered catalyst and ligand were reused without any loss in activity and selectivity. 

These various intermolecular a-acetoxylation reactions have intramolecular counterparts. For example, treatment of the sulfinylbutanoic acid shown in equation (11) with acetic anhydride containing p-toluenesulfonic acid yields a sulfenylated butanolide, the carboxylic acid function having intercepted the a-thiocarbocation intermediate. Yet another demonstration of Ae intramolecular process, due to Al-lenmark, is the cyclization of o-carboxyphenyl benzyl sulfoxide with acetic anhydride to form the 1,3-benzoxathian-4-one shown in equation (12). This reaction was also conducted with one of the... 

Attempted chlorination of benzhydryl benzyl sulfoxide (1) with thionyl chloride in methylene chloride in the presence of either calcium oxide or pyridine resulted in cleavage to benzhydryl chloride (3) and x-toluenesulfinic acid (4). Phenylsulfine (5) is suggested as an intermediate to (4). ... 

In this class of Pummerer reactions subsequent formation of the a-acyloxy sulflde involves, in the majority of instances, an intermolecular acyloxy migration. The reaction of p-tolyl benzyl sulfoxide with acetic anhydride is an exception. However, even in this case no asymmetric induction is observed. ... 

Beilstein Handbook Reference) AI3-62190 Benzene, 1,r-(sulfinylbis(methylene))bis- Benzyl sulfoxide BRN 2049262 Dibenzyl sulfoxide Dibenzyl sulphoxide EINECS 210-668-7 NSC 55 Preventol Cl 5 Sulfoxide, dibenzyl Tardiol D. An organic inhibitor for use in cleansing acids and in the surface treatment of metals. Leaflets mp = 134° bpn 210° (dec) Xm = 220, 253, 260, 266, 270 nm (MeOH) insoluble in H2O, soluble in EtzO,... 

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