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Cyclopropanone derivatives have long been considered unsustainable synthetic intermediates because of their extreme strain and kinetic instability.R eported here is the enantioselective synthesis of 1-sulfonylcyclopropanols,a ss table yet powerful equivalents of the corresponding cyclopropanone derivatives,bya-hydroxylation of sulfonylcyclopropanes using ab is(silyl) peroxide as the electrophilic oxygen source. This work constitutes the first general approach to enantioenriched cyclopropanone derivatives.B oth the electronic and steric nature of the sulfonyl moiety,w hich serves as ab aselabile protecting group and confers crystallinity to these cyclopropanone precursors,w ere found to have ac rucial impact on the rate of equilibration to the corresponding cyclopropanone.T he utility of these cyclopropanone surrogates is demonstrated in amild and stereospecific formal [3+ +1] cycloaddition with simple hydroxylamines,l eading to the efficient formation of chiral b-lactam derivatives.

Sulfone-substituted bicyclo­[1.1.0]­butanes and housanes have found widespread application in organic synthesis due to their bench stability and high reactivity in strain-releasing processes in the presence of nucleophiles or radical species. Despite their increasing utility, their preparation typically requires multiple steps in low overall yield. In this work, we report an expedient and general one-pot procedure for the synthesis of 1-sulfonylbicyclo[1.1.0]­butanes from readily available methyl sulfones and inexpensive epichlorohydrin via the dialkylmagnesium-mediated formation of 3-sulfonylcyclobutanol intermediates. Furthermore, the process was extended to the formation of 1-sulfonylbicyclo[2.1.0]­pentane (housane) analogues when 4-chloro-1,2-epoxybutane was used as the electrophile instead of epichlorohydrin. Both procedures could be applied on a gram scale with similar efficiency and are shown to be fully stereospecific in the case of housanes when an enantiopure epoxide was employed, leading to a streamlined access to highly valuable optically active strain-release reagents.

A new efficient and concise enantioselective synthetic method for (-)-horsfiline is reported. (-)-Horsfiline could be obtained from diphenylmethyl tert-butyl malonate in 9 steps (32%,>99% ee) by using the enantioselective phase-transfer catalytic allylation (91% ee) as the key step. This approach can be applied as a practical route for the large-scale synthesis of spirooxindole natural products, which enables a systematic investigation of their biological activity to be performed.

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