Divergent Reactivity of Alkyl Aryl Sulfones with Bases: Selective Functionalization of ortho-Aryl and alpha-Alkyl Units Enabled by a Unique Carbanion Transmetalation

0427704 - ÚOCHB 2015 RIV DE eng J - Journal Article
Řehová, Lucie - Císařová, I. - Jahn, Ullrich
Divergent Reactivity of Alkyl Aryl Sulfones with Bases: Selective Functionalization of ortho-Aryl and alpha-Alkyl Units Enabled by a Unique Carbanion Transmetalation.
European Journal of Organic Chemistry. Roč. 2014, č. 7 (2014), s. 1461-1476. ISSN 1434-193X. E-ISSN 1099-0690
R&D Projects: GA ČR GAP207/11/1598
Institutional support: RVO:61388963
Keywords : sulfones * transmetalation * lithiation * deprotonation * alkylation * acidity
Subject RIV: CC - Organic Chemistry
Impact factor: 3.065, year: 2014

The electron-accepting sulfonyl group exhibits a strong acidifying influence on neighboring -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 -H atom. The structure of the alkyl unit profoundly, but predictably, influences the regioselectivity of the attack of the base. In - and -branched ortho-(alkylsulfonyl)aryllithiums a transmetalation to the -carbanion proceeds only upon warming. Correspondingly generated ortho- or -carbanions were then selectively applied thus permitting access to synthetically interesting compound classes.
Permanent Link: http://hdl.handle.net/11104/0233203