Copper-catalyzed protoboration of borylated dendralenes: a regio- and stereoselective access to functionalized 1,3-dienes.

A copper-catalyzed protoboration of borylated dendralenes is reported. The method employs an NHC-Cu catalyst and provides access to 1,4-addition products with excellent levels of chemo-, regio- and stereoselectivity. The resulting diene bis(boronates) are oxidized to the corresponding diene diols which are synthetically versatile building blocks.