P-Toluenesulfinate

There are dubious claims for the displacement of the A7-fluorine in perfluoroazetine (240) (60DOK(l3l)l338) by ethanol and for the formation of an azete by reaction of the bicyclic azetine (241) with base. An attempt to produce azete by elimination of p-toluenesulfinic acid from azetine (237 Z = Ts) failed (7UOC435). 

Sodium p-toluenesulfinate [824-79-3] M 178.2, pK 2.80 (1.99)(for -S02 ). Crystd from water (to constant UV spectrum), and dried under vacuum or extracted with hot benzene, then dissolved in EtOH-H20 and heated with decolorising charcoal. The solution was filtered and cooled to give crystals of the dihydrate. 

A. Ethyl N- p-tolylsulfonylmethyl)carhamate,[Carbamic acid, (4 -methyl-phenylsulfonylmethyl)-, ethyl ester]. A solution of 178 g. (1.0 mole) of sodium p-toluenesulfinate (Note 1) in 1 1. of water is placed in a 3-1., three-necked daak, equipped with a condenser, an efficient mechanical stirrer, and a thermometer. After addition of 100 ml. (108 g.) of a 34—37% solution of formaldehyde ca. 1.2-1.4 moles) (Note 2), 107 g. (1.2 moles) of ethyl carbamate (Note 3), and 250 ml. of formic acid (Note 4), the stirred solution is heated to 70°. Soon after this temperature is reached, the reaction mixture becomes turbid by separation of the... 

Commercially available anhydrous sodium p-toluenesulfinate, purum, ca. 97% (Fluka A G, Busch S.G., Switzerland) was used. 

Sodium -tolueuesulfinate dihydrate can be used equally well. The checkers used anhydrous sodium -toluenesulfinate from Aldrich Chemical Company, Inc. This material was determined by titration to be 87% pure and gave lower yields. The yield stated was obtained by using stoichiometric amounts based on calculated purity. Sodium p-toluenesulfinate from other suppliers was found less pure and gave considerably lower yields. 

C and the residual solid was dried in vacuo over P205 overnight and then heated in toluene (20 mL) under reflux until TLC showed that the reaction was complete (15 min). The sodium p-toluenesulfinate produced was filtered off and the filtrate was washed with H20 (2 x 50 mL), dried and evaporated to leave the product yield 0.40 g (78%) oil bp 80 C/10 Torr. HPLC analysis (silica column at 0 T7) showed that the tautomers 7a and 8a were present in the ratio 5.9 1. 

The sodium salt of the tosylhydrazone of 2-(diphcnylmethylene)cyclopentanone (4.99 g, 11 mmol) was boiled under reflux with cyclohexane (150mL) for 25 h and the precipitated sodium p-toluenesulfinate was filtered off. The filtrate was evaporated under reduced pressure and the residue was crystallized (EtOH) to give the product (2.38 g). An additional 0.13 g (total yield 80%) was obtained from the filtrate by chromatography (silica gel) yellow crystals mp 159-160 °C. 

Preparation of enantiomerically pure sulfmate esters has most often been accomplished by making menthyl esters of arenesulfinic acids, particularly of p-toluenesulfinic acid. This... 

An a-fluorinated phosphinyl sulfoxide derivative, prepared as a mixture of diastereomers by the treatment of lithiated (a-fluoromethyl)diphenylphosphine oxide with menthyl p-toluenesulfinate, has been used for the preparation of enan-tiomerically pure 1-fluorovinyl and 1-fluoromethyl sulfoxides [76]. (E)-Diethyl ferf-butylsulfinylmethylphosphonate 117 has been prepared by the sulfinylation... 

Benzaldehyde reacts with formamide and MesSiCl 14 on heating to give, via 435, the N,N-acetal 469, which reacts in situ with p-toluenesulfinic acid, in high yields, to give 470 [58]. The analogous reaction of excess a,)9-unsaturated ahphatic primary amide with aliphatic aldehydes in the presence of TMSOTf 20 in 1,2-di-chloroethane at 25 °C affords the unsaturated N,N-acetals in high yield [58 a]. Benzaldehyde also condenses with excess HMDS 2, in the presence of catalytic amounts of ZnCl2, via 471, to 472 and HMDSO 7 [59] (Scheme 5.21). 

As an alternative, Harpp and coworkers reacted benzenesulfinyl chloride with the trimethylsilyl derivative of menthol to form the diastereomeric esters in 91% yield the epimer of configuration R could be isolated by crystallization in unspecified yield. Grossert and coworkers prepared ester 19 in 51% yield as a mixture of diastereomers by treating p-toluenesulfonyl chloride with sodium p-toluenesulfinate in DMF containing menthol. It was postulated that initial nucleophilic attack by the sulfinate oxygen on the sulfonyl sulfur atom gave the mixed sulfonate-sulfinate anhydride 21, which then reacted... 

A very surprising sulfone formation has been investigated by Oae and coworkers . On heating p-toluenesulfinic acid with dimethylaniline in ethanol for 15 h, the reaction mixture shown in equation 100 has been obtained. Obviously, the observed products arise from an equilibrium between the sulfinic acid and its pseudo-anhydride (disulfide trioxide), which is able to attack the amine nitrogen and degrade the tertiary amine corresponding to a Polonovsky reaction . 

The ion pair mechanism initially suggested by Darwish and McLaren (equation 2) has received further support from related studies conducted by several other investi-gators . For example, Fava and coworkers have reported that during isomerization in acetic acid, optically active benzhydryl p-toluenesulfinate loses optical activity at a rate which is about two and a half times faster than the rate of sulfone formation, thus indicating that return from an ion-pair species is occurring (equation 3). 

By modification of the elegant method of preparation of optically active sulfinates previously reported by Mikolajczyk and coworkers , an efficient stereospecific method for the conversion of readily available optically active sulfinamides to optically active sulfinates of inverted configuration at the sulfinyl function, has been recently reported by Hiroi and coworkers . The same authors subsequently reported the thermal rearrangement of several optically active cis- and trans-y-substituted allylic p-toluenesulfinates to optically active chiral sulfones with high stereoselectivity. For example, trans and cis (S)-( — )-crotyl p-toluenesulfinates rearranged to optically active (S)-(-l-)- and (R)-( — )-a-methylallyl p-tolyl sulfone, respectively (equation 19). 

The use of alkynyliodonium salts in the synthesis of 2,3-disubstituted 4,5-dihydrofurans was reported by Feldman. In this conversion, the addition of p-toluenesulfinate to ethers of 1-hydroxybut-3-ynyl(phenyl)iodonium triflates 79 induces a series of reactions that afford eventually 2-substituted 3-p-toIuenesulfonyl-4,5-dihydrofurans 80 . 

Esterification of p-toluenesulfinic acid with (- )-menthol gives a mixture of two diastereomers, which equilibrate to the pure (-)-menthyl (S)-p-toluenesulfinate diastereomer in the presence of hydrochloric acid (80% yield). The report includes an improved procedure for reaction of 1 with CH,MgI to give (R)-( + )-methyl p-tolyl sulfoxide.1... 

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