title: Reaction of allene esters with Selectfluor/TMSX (X = I, Br, Cl) and Selectfluor/NH4SCN: Competing oxidative/electrophilic dihalogenation and nucleophilic/conjugate addition.
abstract: Reaction of benzyl and ethyl allenoates with TMSX (X = I, Br, Cl) and with NH4SCN were investigated in MeCN, DMF, and in imidazolium ionic liquids [BMIM][NTf2] and [BMIM][PF6] as solvent, in the presence and absence of Selectfluor. Comparative product analysis studies demonstrate that the ability of Selectflour to promote oxidative/electrophilic dihalogenation/dithiocyanation with TMSX/NH4SCN (as observed previously for 1-arylallenes) is diminished in allenoates, most significantly in reactions with TMSCl, and essentially disappearing in reactions with NH4SCN, in favor of nucleophilic/conjugate addition. The study underscores the contrasting reactivity patterns in 1-arylallenes and allenoates toward electrophilic and nucleophilic additions in halofunctionalization with TMSX/Selectfluor and thiocyanation reactions with NH4SCN/Selectfluor. These competing pathways are influenced by the nature of the anion, allene structure, and the choice of solvent.
authors.affiliation: Department of Chemistry, University of North Florida, 1 UNF Drive, Jacksonville, Florida 32224, USA.
authors.forename: A Srinivas
authors.initials: AS
authors.lastname: Reddy
authors.affiliation: Department of Chemistry, University of North Florida, 1 UNF Drive, Jacksonville, Florida 32224, USA.
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Laali
keywords: Selectfluor; TMSX and NH4SCN; allene esters; oxidative electrophilic dihalogenation/conjugate addition