Cyclopropyl phenyl sulfones

Bromo-l-propenyl phenyl sulfone (104) can serve as a Michael acceptor to Grignard reagents to give cyclopropyl phenyl sulfones in good yields, (equation 85)70. Cyclopropanes prepared by this method are listed in Table 8. However, with methyl, ethyl or t-butyl... 

Cyclopropyl sulfones were shown to be obtained either by cyclization of y-p-tosyloxy sulfones 232 with base or by treatment of phenylsulfonylacetonitrile 233a or ethyl phenyl sulfonyl acetate 233b with 1,2-dibromoethane in the presence of benzyltriethyl-ammonium chloride (BTEA) and alkali in good yields. Chang and Pinnick synthesized various cyclopropane derivatives 234 upon initial treatment of carbanions derived from cyclopropyl phenyl sulfone with either alkylating agents or a carbonyl compound and subsequent desulfonylation, as shown below. 

Cyclopropyl phenyl sulfones. 3-Bromo-l-(phenylsultonyl)-l-propene (1), prepared as shown, reacts with allyl, propargyl, aryl, and benzyl Grignard reagents to give (E)-2-substituted cyclopropyl phenyl sulfones (2) in moderate to good yield. This reaction is not observed with alkyl Grignard reagents. 

As far as the situation of the sulfonyl group and derivatives of the sulfonyl group is concerned, there are conflicting results in the literature—at least at first sight. Zimmerman and Thyagarajan " (measurements in ether and hydrocarbon solvents) and Cram and coworkers (measurements in DMSO) reported that the equilibrium acidities of isopropyl- and cyclopropyl phenyl sulfone, 273 and 274, respectively, are roughly equal. 

If the electron-withdrawing group is such that self-condensation does not occur then the anion can be generated in the normal manner. Thus, the anion 349 of cyclopropyl phenyl sulfone (348) can be readily prepared by treatment of the parent compound with n-butyllithium at 0°C in THF. The anion has been shown to condense in excellent yield with aldehydes, ketones, methyl iodide and allyl and benzyl bromides to yield 350. The... 

The anion of 2-(methoxyethoxymethoxy)cyclopropyl phenyl sulfone (methoxyetho-xymethoxy = MEM) is a d -synthon for a,)8-unsaturated aldehydes ". The anion is readily formed by treating 2-(MEM)cyclopropyl phenyl sulfone (359) with n-butyllithium in THE at — 78°C. Treatment of the anion 360 with aliphatic primary bromides or allyl bromide produces the alkylated sulfone 361 in very good yields. Hydrolysis of the MEM-protecting group was readily performed by treatment with aqueous tetrafluoroboric acid to furnish the cyclopropanol sulfone (362). Treatment with aqueous sodium bicarbonate produced the corresponding aldehydes 363 in 70-90 % yields. 

The reaction of 3-bromo-l-(phenylsulfonyl)prop-l-ene with Grignard reagents derived from allyl bromide, 2-propynyl bromide, bromobenzene, benzyl bromide or l-bromo-3-methylbut-2-ene affords 2-substituted cyclopropyl phenyl sulfones. On the other hand, alkylmagnesium bromides give the corresponding y-substituted allyl derivatives (Table 20, entries 6-8). 

Under the same basic conditions /ra . -l-acetoxymethyl-1-methyl-2-tosylcyclopropane generated an a-sulfonyl anion, which attacked the ester group intramolecularly and afforded 2,5-dimethyl-l-tosyl-3-oxabicyclo[3.1.0]hexan-2-ol (22) in 50% yield.Stereoselective synthesis with a chiral cyclopropyl sulfoxide was experienced when ( )-4-tolylsulfinylcyclopropane was reacted first with butyllithium and then with methyl benzoate and gave 1-benzoyl-1-[(5)-4-tolylsulfinyl]cyclopropane (23a) in 62% yield. A useful reaction took place when 2-(hy-droxymethyl)cyclopropyl phenyl sulfide was treated first with an excess of butyllithium and then with dimethylformamide and gave 2-hydroxy-l-phenylsulfanyl-3-oxabicyclo[3.1.0]hexane (24), a lactol which has been used to carry out various useful synthetic transformations. Another useful reaction occurred when cyclopropyl phenyl sulfones were treated with butyllithium followed by an acyl imidazole to give acyl cyclopropanes in decent yield. 

An alkylidenecyclopropane has been obtained by treating 11-bromo-ll-trimethylsilyltri-cyclo[4.4.1.0 ]undecane with formaldehyde. In another successful synthesis cyclopropyl phenyl sulfone is used as starting material treatment with butyllithium followed by an acylsilane leads to a 1-cyclopropylidene-l-silyloxyalkane 3. ... 

Efficient oxidation also results from treatment of cyclopropyl phenyl sulfide (7) with ( —)-camphorsulfonyloxaziridines 8. Due to the optical activity of the reagents, the product cyclopropyl phenyl sulfoxide 9 is optically active. The best results were obtained when (-)- , -dichlorocamphorsulfonyloxaziridine [( —)-8b] was used the sulfoxide was obtained in 90% yield with 92% ee of the 5 -isomer. Application of ( —)-camphorsulfonyloxaziridine ( —)-8a, on the other hand, lowered both the yield and the enantiomeric excess to 23%.Moderate optical purity was obtained when cyclopropyl phenyl sulfide was incubated with Mortierella isabellina, cyclopropyl phenyl sulfoxide was isolated in 58% yield with 66%ee of the (-1-)-sulfoxide, together with cyclopropyl phenyl sulfone (2% yield). Optically inactive cyclopropyl phenyl sulfoxide was obtained in 98% yield when the corresponding sulfide was treated with sodium metaperiodate. ... 

Boidwell estimated the pKa of A 3-dimethyl-5-phenylsulfoximine (141) in DMSO to be about 33, less acidic than methyl phenyl sulfone by about 4 pK units. From a cyclopropyl effect on the equilibrium acidity of Af-phenylsulfonyl-5-methyl-5-phenylsulfoximine (142), it was concluded that the carbanion is planar or nearly planar to the sulfonimidoyl group.However, on the basis of the 7ch coupling constant in a NMR spectroscopic study, it was concluded by Marquet that the configuration of the lithi-ated a-carbon (142) is pyramidal. ... 

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