Gold(I)‐Catalyzed [8+2]‐Cycloaddition of 8‐Aryl‐8‐azaheptafulvenes with Allenamides and Ynamides: Regioselective Synthesis of Dihydrocycloheptapyrrole Derivatives
Tatiana Suárez‐Rodríguez, A.L. Suarez-Sobrino, Alfredo Ballesteros
Abstract
Abstract Gold(I)‐catalyzed higher‐order [8+2] cycloadditions of 8‐aryl‐8‐azaheptafulvenes 1 with allenamides 2 and ynamides 3 were studied. 1,8‐Dihydrocycloheptapyrroles 4 were achieved by a regioselective [8+2] cycloaddition of azaheptafulvenes 1 and allenamides 2 in the presence of (2,4‐di t BuC 6 H 3 O) 3 PAuNTf 2 as catalyst. Besides, ynamides 3 and 8‐aryl‐8‐azaheptafulvenes 1 , undergo a regioselective [8+2] cycloaddition, to give 2‐amido‐1,4‐dihydrocycloheptapyrroles 7 in the presence of JohnPhosAuNTf 2 as catalyst. Both reactions take place with good yields and with a variety of substituents. A plausible mechanism hypothesis suggests a nucleophilic attack of the 8‐azaheptafulvene to the gold activated electron rich allene or alkyne moieties of the allenamide and ynamide, respectively.