Keynote article. Nickel catalysed coupling of allylamines and boronic acids

Abstract

Allylamines function as substrates for cross-coupling with boronic acids in the presence of nickel(0) catalysts rather than palladium(0) catalysts. Aryl,- vinyl- and methyl-boronic acids function well. With vinyl derivatives, E-isomers couple more efficiently than Z-isomers and both fully retain the geometrical integrity. Methylations preferably employ the boronic esters like 2-methyl-1,3,2-benzodioxaborole or 2-methyl-1,3,2-dioxaborolane rather than methylboronic acid. The stereochemistry of the reaction involves a net inversion with respect to the allylamine. The regioselectivity is a function of ligand. Generally, sterically bulky donor phosphines promote new C–C bond formation at the less substituted position. Bidentate ligands, notably 1,1′-binaphthyl-2,2′-ylbis(diphenylphosphinite)(BINAPO), promote new C–C bond formation at the more substituted allyl terminus. The amines appear to be the preferred partner compared to allyl alcohols and esters with the boronic acids and give higher stereospecificity.