Catalytic Intermolecular Linear Allylic C−H Amination via Heterobimetallic Catalysis

Abstract

A novel heterobimetallic Pd(II)sulfoxide/(salen)Cr(III)Cl-catalyzed intermolecular linear allylic C−H amination (LAA) is reported. This reaction directly converts densely functionalized α-olefin substrates (1 equiv) to linear (E)-allylic carbamates with good yields and outstanding regio- and stereoselectivities (>20:1). Chiral bis-homoallylic and homoallylic oxygen, nitrogen, and carbon substituted α-olefins undergo allylic C−H amination with good yields, excellent selectivities, and no erosion in enantiomeric purity. Streamlined routes to (E)-allylic carbamates that can be further elaborated to medicinally and biologically relevant allylic amines are also demonstrated. Valuable 15N-labeled allylic amines may be generated directly from allyl moieties at late stages of synthetic routes by using the readily available 15N-(methoxycarbonyl)-p-toluenesulfonamide nucleophile. Evidence is provided that this reaction proceeds via a heterobimetallic mechanism where Pd/sulfoxide mediates allylic C−H cleavage to form a π-allylPd intermediate, and (salen)Cr(III)Cl/BQ work together to promote functionalization with the nitrogen nucleophile.