1593772-57-6Relevant articles and documents
Divergent Reactivity of Alkyl Aryl Sulfones with Bases: Selective Functionalization of ortho-Aryl and α-Alkyl Units Enabled by a Unique Carbanion Transmetalation
?ehová, Lucie,Císa?ová, Ivana,Jahn, Ullrich
, p. 1461 - 1476 (2014)
The electron-accepting sulfonyl group exhibits a strong acidifying influence on neighboring α-H atoms. The Julia and related olefinations are based on this effect. Here a surprising reversal in the metalation selectivity of branched alkyl aryl sulfones is described. Such sulfones were found to initially undergo directed ortho-metalation with good regioselectivity, despite having a more acidic α-H atom. The structure of the alkyl unit profoundly, but predictably, influences the regioselectivity of the attack of the base. In β- and γ-branched ortho-(alkylsulfonyl)aryllithiums a transmetalation to the α-carbanion proceeds only upon warming. Correspondingly generated ortho- or α-carbanions were then selectively applied thus permitting access to synthetically interesting compound classes.
