Silyl Group‐Directed 6‐exo‐dig Iodocyclization of Homopropargylic Carbamates and Amides

Iodocyclization of silyl group‐substituted homopropargylic carbamates and amides proceeded via 6‐exo‐dig mode to afford 6‐vinylene‐4,5‐dihydro‐1,3‐oxazines in moderate to quantitative yields. This is the first report for silyl group‐solely directed iodocyclization of alkynes utilizing the β‐silyl effect. Under these mild reaction conditions, various functionalities such as secondary alcohol, acetal, urea, and sulfide were tolerated. A silyl group efficiently directed the electrophilic cyclization mode to exo in the iodocyclization of homopropargylic carbamates and amides, leading to cyclic imidates.