Phenylsulfinate

Work at Rhc ne-Poulenc has involved a different approach to retinal and is based on the paHadium-cataly2ed rearrangement of the mixed carbonate (41) to the aHenyl enal (42). Isomerization of the aHene (42) to the polyene (43) completes the constmction of the carbon framework. Acid-catalyzed isomerization yields retinal (5). A decided advantage of this route is that no by-products such as triphenylphosphine oxide or sodium phenylsulfinate are formed. However, significant yield improvements would be necessary for this process to compete with the current commercial syntheses (25—27) (Fig. 9). 

In the case of diaryl sulfoxides the formation of both the aryl radical and the hydroxycyclohexadienyl radical was observed optically. Veltwisch and coworkers45 studied also the reaction of OH radicals from radiolysis of aqueous solutions of mixed (alkyl phenyl) sulfoxides (PhSOR). They found the formation of both alkylsulfinic and phenylsulfinic acids. 

Chloro-5-phenyl-l,3,4-thiadiazole 52 reacts with thiourea in refluxing ethanol to afford the thione 61 (Equation 11) <2000MI31>. The reaction of sodium phenylsulfinate with thiadiazole 62 in refluxing dimethylfor-mamide (DMF) gave the 5-phenylsulfonyl-l,3,4-thiadiazole 63 (Equation 12) <1999AF1035>. 

A few nucleophiles either did not give any spin adduct with PBN or directly gave the benzoyl nitrone [9], Bromide ion did not give any spin adduct, explicable by the very short lifetime of Br-PBN (Rehorek and Janzen, 1984) and trifluoroacetate, nitrate, phenylsulfinate and chloride ion produced [9]. This can either be explained by the rapid further oxidation of the spin adduct formed [similar to reaction (29) see Table 4] or a rapid solvolysis reaction of the latter (Scheme 2), forming [9] by reaction of the intermediate carbocation... 

Elimination of phenylsulfinate anion, induced by base, introduces one double bond. The second double bond can be introduced by DDQ oxidation, as in Scheme 43. 

The addition of sodium phenylsulfinate nucleophiles to stereodefined acyclic allylic chlorides was reported to proceed with complete overall retention of configuration, indicating that this nucleophile adds with inversion of configuration, i.e. via attack at the allyl ligand (equation 193).21S A cyclohexenyl acetate substrate also showed predominant ligand addition, but some isomeric product was also produced (equation 194).216 This loss could be due to acetate epimerization of starting material, ir-allyl epimeriza-tion by PdL2, or by attack of the sulfur at the metal, followed by reductive elimination. 

Toda, F., Tanaka, K., and Okuda, T. (1995) Optical Resolution of Methyl Phenyl and Benzyl Methyl Sulfoxides and Alkyl Phenylsulfinates by Complexation with Chiral Host Compounds Derived from Tartaric Acid, J. Chem. Soc., Chem. Commun., 639-640. 

The synthesis of 4,5-dicyano-l,2,3-trithiole 2-oxide (172) starts from sodium cyanide and carbon disulfide which via (170) gave the disodium salt of 2,3-mercaptomaleonitrile (171 M = Na). Treatment of the corresponding silver salt (171 M = Ag) with thionyl chloride yielded (172) <66HC(2l-l)l). Phenylsulfine (174), prepared in situ by dehy-drohalogenation of phenylmethanesulfinyl chloride (173), slowly decomposed in ether solution at room temperature to give cis- and trans-stilbenes, mms-4,5-diphenyl-l,2,3-trithiolane 1,1-dioxide (36) and a 5,6-diphenyl-l,2,3,4-tetrathiane dioxide (68JCS(C)1612). The mechanisms of formation of these heterocycles are obscure. 

Nitro-l-(phenylsulfonyl)indole undergoes nucleophilic substitution reactions with enolates, for example, of diethyl malonate and cyclohexanone (Scheme 77), to afford the corresponding 3-substituted 2-nitroindoles <1997TL5603, 1999TL7615>. Similar S -type displacements of phenylsulfinate work very efficiently in an intramolecular sense (e.g., Scheme 78) <1999PHC45>. 

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). ... 

Palladium-catalyzed addition of phenylsulfinic acid to butadiene and isoprene gave mainly 1,2-addition products. From butadiene, a 4 1 ratio of 1,2- to 1,4-addition product was obtained in high yield [Eq.(ll)] [27]. It was later shown that the 1,2-addition product is the kinetic product and that prolonged reaction time increased the amount of 1,4-addition product [27b]. 

Substituted l,2-bis(phenylsulfonyl)benzenes are cleaved in a one-electron reaction with loss of phenylsulfinate. The substituted aryl radical may react with formation of derivatives of dibenzothiophene and other products [163]. l,4-Bis(alkylsulfonyl)benzenes... 

This overall synthetic strategy (see Figure 11.8) was adapted to give a range of isomeric pyrido[2,3-/z]pyrazincs structures 34 by simply varying the order of reaction with appropriate mono- and difunctional nucleophiles [57, 58] (see Table 11.6). For example, reaction of sodium phenylsulfinate with pentafluoropyridine gives the... 

The so-called thia-Fries rearrangement occurs upon treatment of aryl phenylsulfinates 235 (obtained by reaction of phenols with phenylsulfinyl chloride) with AICI3 at 25 °C to afford the (phenylsulfinyl)phenols 236 in good yields (equation 107) . 

Accordingly, bishydroxylation of the enol ether then gave an 80% yield of hydroxy ketones 37a and 37b. The ratio of these two compounds varied depending upon the reaction conditions, but the desired syn compound 37a always was major product in at least a 3 1 ratio. Succinylation of the mixture of 37a and 37b followed by -elimination of phenylsulfinic acid gave a mixture of diastereomeric lactones from which synthetic 1 could be isolated. 

However, this mechanism was excluded on the basis of the reaction of the 2-pyridylsulfone (198) with 5-hexenylmagnesium bromide which did not give any 2-(cyclopentylmethyl)pyridine (199), which would be expected for a radical process. The only isolated compound was the ligand coupling type product (200) in 99% yield. 131 In spite of these suggestions, the mechanism is more likely to be a simple addition on the C-2 atom of the pyridine ring, followed by elimination of phenylsulfinic acid. 

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