Iron-Catalyzed Decarboxylative (4+1) Cycloadditions: Exploiting the Reactivity of Ambident Iron-Stabilized Intermediates

The first example of iron‐catalyzed decarboxylative (4+1) cycloaddition reactions is described in this publication. By using this method, a wide range of functionalized indoline products were prepared from easily available vinyl benzoxazinanones and sulfur ylides in high yields and selectivities. A possible reaction pathway involving an allylic iron intermediate is discussed based on a series of control experiments and density‐functional theory calculations. Going in reverse: The first example of iron‐catalyzed decarboxylative formal (4+1) cycloaddition reactions, which exploit the reverse reactivity of ambident iron‐stabilized intermediates, was developed. By using this method, a wide range of functionalized indoline products were facilely prepared in generally good yields and high stereoselectivities from easily available starting materials. Ts=4‐toluenesulfonyl.