Cyclopropyl sulfonates

Substitution of the -methyl group of penicillanic acid sulfone has also been extensively investigated. The cyclopropyl sulfone (25, R = R = H,... 

Aryl 3-chloropropyl sulfones 231 were shown to cyclize to aryl cyclopropyl sulfones upon treatment with t-BuOK in r-butanol283 or with sodium amide in 1,2-dimethoxyethane284. Bird and Stirling285 investigated the reaction of aryl 3-chloropropyl... 

Grignard reagents, no detectable amount of cyclopropyl sulfones is formed. 

TABLE 8. Preparation of cyclopropyl sulfones from 104 and Grignard reagents70... 

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. 

Optically pure methylenecyclopropanes 59 were synthesized from cyclopropyl sulfones 58 and the carbenoid, iodomethylmagnesium chloride, in moderate to good yields (equation 15). ... 

Analogously, several dichloro- or difluoro-cyclopropyl ketones provide y-oxo-esters under similar conditions 48-49), whereas dichloro-cyclopropyl sulfones give y-sulfonyl orthoesters 50>. 

It may rather be that in the case of third row substituents like R4P the relative acidity of cyclopropyl and isopropyl hydrogens is not as indicative of the carbanion configuration as in the case with the second row substituents C(0)R, CN and possibly NO2. As far as cyclopropyl sulfones are concerned one would therefore predict that the corresponding a-sulfonyl cyclopropyl anions may have a pyramidal configuration. The deprotonation of cyclopropyl phosphonates, followed by reaction with aldehydes, was recently published by Hirao and coworkers ... 

Ketosulfones like (117) and (118) are readily alkylated and acylated. The alkylation may occur either at carbon or at oxygen depending on the reaction conditions (Scheme 51). Furthermore, one-pot alkylation using suitable dihaloalkanes occurs to yield cyclic products such as the cyclopropyl sulfone (119), as shown in Scheme 51. 

Cyclopropyl sulfones 3 are easily reduced to cyclopropanes 4 by treatment with sodium amalgam in refluxing ethanol. Yields above 80% have been reported.However, quite different reaction conditions are required to perform reductive desulfurization of cyclopropanesulfinic acids 5, i.e. the use of mercury(II) chloride, concentrated hydrochloric acid, and heat ethylmagnesium bromide followed by acid has also been used but yields were poor. ... 

In one case a cyclopropyl sulfone was converted to the corresponding cyclopropane by photochemical sulfur dioxide extrusion. Examples of Raney nickel desulfurization can be found in refs 921 and 922,... 

A large number of cyclopropanes have been synthesized from cyclopropyl sulfones, cyclopropyl sulfoxides and cyclopropyl sulfides by taking advantage of the acidity of the cyclopropyl proton a to the C-S bond. Butyllithium is used almost exclusively as the base. The cyclopropyl anions obtained are capable of reacting with alkyl halides, aldehydes, enamines, epoxides, esters. 

Double substitution by successive elimination and addition also takes place when 1-chloro-cyclopropanecarboxylates and 1-chlorocyclopropyl cyclopropyl sulfone are treated with potassium ieri-butoxide in tetrahydrofuran. The best result was obtained with the sulfone, which was converted to 2-feri-butoxycyclopropyl cyclopropyl sulfone (3) in 82% yield. ... 

Z-tert-Butoxycyclopropyl Cyclopropyl Sulfone (3) Typical Procedure ... 

To a solution of 1-chlorocyclopropyl cyclopropyl sulfone (1.13 g, 6.25 mmol) in anhyd THF (4 mL) cooled to 0 "C under Nj was added powdered r-BuOK (2.0 g, 18.0 mmol) in small portions. The resulting mixture was stirred at rt for 3 h and was then concentrated by distillation with the aid of a stream. The distillate... 

Cyclopropyl acetates have been obtained by using cyclopropyl sulfonates as starting materials. e rfo-10-Trifluoromethanesulfonyloxytricyclo[4.3.1. OJdecane and ent/o-lO-trifluoromethanesul-fonyloxytricyclo[4.3.1.0]dec-3-ene reacted with sodium acetate in acetic acid to give the corresponding acetates with retention of configuration in 44 and 11% yield, respectively. ... 

Truce, W. E., and V. V. Badiger Reaction of Dimethylsulfonium Methylide with Vinylic Sulfones. Formation of Aryl Cyclopropyl Sulfones. J. Org. Chem. 29, 3277 (1964). 

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