Scope and Limitations of a Modified Sonogashira Cross-Coupling Protocol: Development of Synthetic Orthogonality

Nicholas Ball
Macalester University

A modification of Sonogashira cross coupling generates symmetric or unsymmetric bisarylethynes in one-pot. The key procedural modification involves the use of an amidine base and a substoichiometric amount of water. In particular, in situ protodesilylation follows installation of a trimethylsilylethynylene moiety, permitting a second cross coupling reaction to proceed. Examples of this modified Sonogashira protocol will be presented, along with recent results that establish several useful points of orthogonal reactivity.