Cyclopropyldiphenylsulfonium tetrafluoroborate

Isolated carbonyls always give epoxides from the Corey-Chaykovsky reaction. Take the aldehyde substrate as an example. Spiro epoxide 30 was produced from the reaction of trisnorsqualene aldehyde 28 (R20 represents the polyene side-chain with 20 carbons) with substituted sulfur ylide 29, prepared in situ from cyclopropyldiphenylsulfonium tetrafluoroborate and KOH. " For the epoxidation of ketones, the Corey-Chaykovsky reaction works well for diaryl- (31), arylalkyl- (32), ... 

Diphenylsulfonium cyciopropanide has been generated irreversibly Method A, by reaction of triphenylsulfonium tetrafluoroborate with cyclopropyllithium in tetrahydrofuran at — 78°C 61,65 or Method B, by treatment of cyclopropyldiphenylsulfonium tetrafluoroborate with sodium methylsulfinylmethanide in 1,2-dimethoxyethane at —40°C.57,65 However, reversible formation from cyclopropyldiphenylsulfonium tetrafluoroborate with Method C, powdered potassium hydroxide in dimethyl sulfoxide at + 25 °C, is easier to perform and gives higher yields of cyclobutanones l.62 A large-scale preparation of cyclopropyldiphenylsulfonium tetrafluoroborate has been reported.65,66... 

Oxaspiropentanes have been obtained from the cyclopropylide 103, prepared by treatment of cyclopropyldiphenylsulfonium tetrafluoroborate 102 either with sodium methylsulfmyl carbanion in dimethoxyethane at —45 °C or with potassium hydroxide in dimethylsulfoxide at 25 °C. While the reaction of the ylide 103 with a,p-unsaturated carbonyl compounds has resulted in selective cyclopropylidene transfer to the a, 3-carbon-carbon double bond leading to spiropentanes, condensation of 103 with non-conjugated aldehydes and ketones led to oxaspiropentanes such as 104, which have been isolated in 59-100% yields, Eq. (30) 57). 

Cationic polymerization of thiiranes CMT (9-(thiiran-2-ylmethyl)-9//-carbazole) 217 and PMT (10-(thiiran-2ylmethyl)-1077-phenothiazine) 218 was studied by a Lithuanian group <2002JPH63>. Initiators were di-(/-butylphenyl)iodonium tetrafluoroborate (BPIT), diphenyliodonium tetrafluoroborate, cyclopropyldiphenylsulfonium tetrafluoroborate, and ( 7 -2,4-cyclopentadien-1 -yl) [1,2,3,4,5,6- )-( 1 -methylethyl)benzene]-iron(- -)-hexafluorophosphate(—1). The influences of temperature and initiator concentration on the polymerization rate and the conversion limit were determined. The values of initiator exponent and activation energy for the photopolymerization of CMT and PMT initiated with BPIT in 1,2-dichloroethane was established. 

Cyclopropyldiphenylsulfonium tetrafluoroborates 89 are versatile three-carbon building blocks. " Upon reaction with base, e.g. sodium methylsulfinylmethylide in 1,2-dimethoxyethane or potassium hydroxide in dimethyl sulfoxide, these salts are converted into ylides 90 which readily react with ketones or acrylates to afford spiroepoxides 91 or spiro[2.2]pentane-l-carboxylates 92, respectively. -Similar reactions were observed with (dimethylamino)phenylsulfoxonium cyclopropylide. ... 

An alternative and excellent route to oxaspiropentanes 83 and thus of cyclobutanones 84 proceeds through the condensation of cyclopropyldiphenylsulfonium tetrafluoroborate (82) with aldehydes and ketones. Table 2 presents some illustrative examples. With cyclopropyl methyl ketone and benzophenone as substrates, the oxaspiropentanes cannot be isolated but rapidly rearrange to the corresponding cyclobutanones." Here ring expansion is facilitated by the presence of excellent carbenium ion stabilizing groups. 

Table 2. Synthesis of Various Oxaspiropentanes and Cyclobutanones Utilizing Cyclopropyldiphenylsulfonium Tetrafluoroborate ...

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