Diphenylsulphonium cyclopropylide

A lot of progress in this area is due to the work of Trost, who introduced diphenylsulphonium cyclopropylide and phenylthiocyclopropyl lithium as extremely versatile C3-building blocks. The first reagent is easily available from the corresponding sulphonium salt by deprotonation with suitable bases (either under irreversible conditions with dimsyl sodium, or, preferably, in a reversible manner by employing potassium hydroxide in DMSO). The ylide adds to a,) -unsaturated carbonyl compounds forming... 

Due to efforts of Conia s (equation 148) and Trost s groups access to more substituted vinylcyclopropanes has been gained operating with siloxy derivatives prepared either by Simmons-Smith cyclopropanation or using diphenylsulphonium cyclopropylide as a key substance (see Section VI.D.l). Oxidative rearrangement has led to a cyclopentanol... 

Oxaspiropentanes have been also obtained in 59-100 % yields from the condensation of aldehydes and ketones with the diphenylsulphonium cyclopropylide prepared by treatment of the cyclopropyldiphenylsulphonium fluoroborate (119) with solid potassium hydroxide in dimethyl sulphoxide at 25°C (equation... 

The recently described sulphur ylide diphenylsulphonium cyclopropylide (172), which converts saturated ketones into spirocyclobutanones, reacted with a steroidal 4,6-dien-3-one in a more complex manner. Two moles of the reagent were incorporated to give the spiro[2,4]heptan-4-one (173) and the epimer at the C-3 position of the steroid. Scheme 7 illustrates the likely reaction path. ... 

Reagents i. BrCH(C02Bu >2-Me2NC(=NH)NMe2 ii, diphenylsulphonium cyclopropylide-KOH iii, NaBH4-Mg(OMe)2... 

Miscellaneous.—a-Elimination. Further examples of cyclobutanone synthesis employing lithium diphenylsulphonium cyclopropylide have been reported. ... 

Miscellaneous.—OrElimination. Lithium diphenylsulphonium cyclopropylide continues to be used in cyclobutanone synthesis, and a more efficient rearrangement of the initially produced spiro-epoxide is achieved by the use of lithium tetrafluoro-borate. A promising alternative route to cyclobutanones is shown in Scheme 64,... 

Cyclobutanones.—A wide variety of cyclobutanones have been prepared by the reaction of ketones or aldehydes with diphenylsulphonium cyclopropylide or with... 

Diphenylsulphonium cyclopropylide reacts with ketones to give good yields of the previously elusive oxaspiropentanes as shown in Scheme 82. By flash distillation in vacuo, pure compounds (628) were isolated. Alternatively, the oxaspiropentanes may be isomerized to cyclobutanones in high yield, and... 

Synthesis and Properties.—The two most general methods for preparing sulphonium ylides continue to be a-deprotonation of a sulphonium salt and the reaction of a sulphide (or disulphide with a carbene. A new development involves the reaction of the thianthrene or phenoxathiin cation radical with a dicarbonyl compound, e.g. ethyl benzoylacetate, to give (4). An infrequently used but useful route to sulphonium ylides involves reaction of sulphides e.g. dithia[3,3]cyclophanes with benzyne. A detailed description of a preparation of the sulphonium salt precursor to Trost s diphenylsulphonium cyclopropylide has appeared. The selectivity of ylide formation in the reaction of cyclic and acyclic sulphides with carbenes has been examined and compared with the much... 

---