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.
1-Sulfonylcyclopropanols are employed here as efficient cyclopropanone equivalents in a formal vinylidene insertion process, providing the first general synthetic route to enantioenriched alkylidenecyclobutanones. The addition of an alkenyl-Grignard reagent leads to an alkenylcyclopropanol capable of electrophilic activation by N-bromosuccinimide, triggering a regio-and stereospecific 1,2-migration and affording alkylidenecyclobutanones after elimination. Activation of the intermediate with other electrophiles such as HCl or mCPBA leads to the formation of various chiral cyclobutanones and γ-lactones via alternative pathways.
The addition of organometallic reagents to ketones constitutes one of the most straightforward synthetic approaches to tertiary
alcohols. However, due to the absence of a well-behaved class of cyclopropanone surrogates accessible in enantioenriched form, such a trivial
synthetic disconnection has only received very little attention in the literature for the formation of tertiary cyclopropanols. In this work, we
report a simple and high-yielding synthesis 1-substituted cyclopropanols via the addition of diverse organometallic reagents to 1-
phenylsulfonylcyclopropanols, acting here as in situ precursors of the corresponding cyclopropanones.The transformation is shown to be amenable to sp, sp2 or sp3
-hybridized organometallic C-nucleophiles under mild conditions, and the use of enantioenriched substrates led to highly
diastereoselective additions and the formation of optically active cyclopropanols.
The addition of organometallic reagents to ketones constitutes one of the most straightforward synthetic approaches to tertiary alcohols. However, due to the absence of a well-behaved class of cyclopropanone surrogates accessible in enantioenriched form, such a trivial synthetic disconnection has only received very little attention in the literature for the formation of tertiary cyclopropanols. In this work, we report a simple and high-yielding synthesis 1-substituted cyclopropanols via the addition of diverse organometallic reagents to 1phenylsulfonylcyclopropanols, acting here as in situ precursors of the corresponding cyclopropanones. The transformation is shown to be amenable to sp, sp 2 or sp 3-hybridized organometallic C-nucleophiles under mild conditions, and the use of enantioenriched substrates led to highly diastereoselective additions and the formation of optically active cyclopropanols.
The direct and selective α-halogenation of alkyl sulfones was achieved via base-mediated electrophilic halogenation, where reagent–solvent halogen bonding was found to control the selectivity through alteration of the effective size of the halogen source.
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