Selectivity Control by Silver Catalysts in the Cycloisomerization of 1,6-Enynes Derived from Propiolamides

Abstract

Silver-catalyzed cycloisomerizations of 1,6-enynes derived from propiolamides led to a selective formation of Alder-ene type 1,4-dienes. Interestingly, AgNTf2 outperformed gold or platinum catalysts in terms of selectivity and reactivity, providing the 1,4-dienes at room temperature. The presence of C(5) carbonyl group in combination with Ag salts is key to the selectivity and the -oxo coordinated silver carbenoids was proposed as an intermediate based on the reaction profiles.