RESUMEN
Synergistic organoboron/palladium cocatalysis enables dehydrative couplings of NH-sulfoximines with allylic alcohols, furnishing the corresponding N-allylated products. The reactions proceed in the absence of a Brønsted base and are tolerant of diverse sulfoximine partners, including functionalized variants. Experimental and computational studies suggest that the sulfoximine reagent is activated by complexation to the boronic acid cocatalyst.
RESUMEN
A method for regioselective palladium-catalyzed allylic alkylation of ambident nitrogen heterocycles, employing simple allylic alcohols as electrophile precursors, is described. An organoboron co-catalyst serves both to activate the azole-type nucleophile toward selective N-functionalization and to accelerate the formation of a π-allylpalladium complex from the allylic alcohol. The method can be applied to various heterocycle types, including 1,2,3- and 1,2,4-triazoles, tetrazoles, pyrazoles, and purines, and can be extended to substituted allylic alcohol partners.
Asunto(s)
Azoles , Paladio , Propanoles , Catálisis , Triazoles , Nitrógeno , Purinas , Pirazoles , TetrazolesRESUMEN
A method for regioselective N-alkylation of ambident, azole-type heterocycles with alkene or epoxide electrophiles is described. In the presence of diphenylborinic acid (Ph2BOH) and an amine cocatalyst, heterocyclic nucleophiles such as 1,2,3- and 1,2,4-triazoles, substituted tetrazoles, and purine are activated toward selective N-functionalization. The scope of electrophilic partners includes enones, 2-vinylpyridine, phenyl vinyl sulfone, a dehydroalanine derivative, and epoxides. Mechanistic studies, including in situ 11B NMR spectroscopy and kinetic analysis, are discussed.