Gold(I)-Catalyzed [8+2]-Cycloaddition of 8-Aryl-8-azaheptafulvenes with Allenamides and Ynamides: Regioselective Synthesis of Dihydrocycloheptapyrrole Derivatives |
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| Authors: | Dr Tatiana Suárez-Rodríguez Prof Dr Ángel L Suárez-Sobrino Prof Dr Alfredo Ballesteros |
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| Institution: | Departamento de Química Orgánica e Inorgánica, Instituto de Química Organometálica “Enrique Moles“, Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain |
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| 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-ditBuC6H3O)3PAuNTf2 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 JohnPhosAuNTf2 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. |
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| Keywords: | 8-azaheptafulvenes cycloaddition gold higher-order cyclization homogeneous catalysis |
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