124992-97-8Relevant articles and documents
Development of Palladium-Catalyzed Decarboxylative Allylation of Electron-Deficient Sulfones and Identification of Unusual Side Products
Gill, Monica A.,Manthorpe, Jeffrey M.
, p. 6028 - 6039 (2019/05/24)
The use of sulfones as electron-withdrawing groups in substrates for palladium-catalyzed decarboxylative allylation was explored. A previously published trifluoromethanesulfonyl-based substrate was highly reactive and selective under mild conditions, but the substrate scope was not readily expanded. Instead, 3,5-bis(trifluoromethyl)phenyl sulfones were employed, thereby simultaneously retaining most of the electron deficiency and providing facile synthetic access. Optimization of the catalytic conditions to maximize the product distribution to a synthetically useful level of the allylation product over the protonation side product proved extremely challenging, with inconsistent and irreproducible results afforded with Pd2(dba)3 as the palladium source. A variety of substrates were subjected to the optimized catalytic conditions of PdCp(1-cinnamyl) and Xantphos in tetrahydrofuran at 50 °C for 30 min. These conditions were applicable to all substrates with the exception of the α,α-dimethyl allyl ester, which required more forcing conditions and afforded four products: the allylation and protonation products, as expected, along with a cyclopropylation product and an unprecedented pseudodimeric product. The mechanism for the formation of these unusual side products is considered.
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
supporting information, p. 1461 - 1476 (2015/10/05)
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.
Alkene synthesis: Elimination of arenesulfinic acid from alkyl aryl sulfones using potassium trimethylsilanolate as base
Baker-Glenn, Charles A.G.,Barrett, Anthony G.M.,Gray, Andrew A.,Procopiou, Panayiotis A.,Ruston, Mark
, p. 7427 - 7430 (2007/10/03)
The use of potassium trimethylsilanolate as base to induce elimination of potassium arenesulfinate from alkyl aryl sulfones to produce E-alkenes is described. The reaction was appropriate for substrates containing a benzyl or allyl group α to the sulfone
