Titanium-Promoted Cross-Coupling for the Selective Synthesis of Polysubstituted, Conjugated Amides.
α,β-Unsaturated amides are important building blocks and are key structural elements in a number of biologically active natural products. Despite their importance and prevalence, few methods exist to prepare conjugated amides directly and modularly. To address this gap, a titanium-promoted coupling of alkynes and isocyanates has been developed. The method is highly stereoselective, producing only the E isomer with good chemoselectivity and regioselectivity (>95/5), for unsymmetrical internal alkynes that contain a steric bias. The reactive titanacyclopentene intermediate formed from the coupling of the alkyne and isocyanate was additionally reacted with various electrophiles to access tetrasubstituted enamides.
Department of Chemistry, Oklahoma State University , 107 Physical Sciences 1, Stillwater, Oklahoma 74078, United States.
Vinoth Kumar
VK
Chenniappan
Department of Chemistry, Oklahoma State University , 107 Physical Sciences 1, Stillwater, Oklahoma 74078, United States.
Ronald J
RJ
Rahaim