Highly Stereoselective Synthesis of (1<i>E</i>)‐2‐Methyl‐1,3‐dienes by Palladium‐Catalyzed <i>trans</i>‐Selective Cross‐Coupling of 1,1‐Dibromo‐1‐alkenes with Alkenylzinc Reagents

Abstract

Ligand control: The use of Pd complexes containing tBu3P or nitrogen-heterocyclic carbene (NHC) ligands almost completely prevents stereoisomerization, thereby permitting an efficient and selective methylation and higher alkylation of (Z)-2-bromo-1,3-dienes (see scheme, dba=trans,trans-dibenzylideneacetone).