Single and Consecutive Cyclization Reactions of Alkynyl Carbene Complexes and 8-Azaheptafulvenes: Direct Access to Polycyclic Pyrrole and Indole Derivatives
作者:José Barluenga、Jaime García-Rodríguez、Ángel L. Suárez-Sobrino、Miguel Tomás
DOI:10.1002/chem.200901257
日期:2009.9.7
The reactivity of alkynyl and enynyl Fischer carbene complexes towards 8‐azaheptafulvenes is examined. Alkynyl carbenes 1 a–f undergo regioselective [8+2] heterocyclization with 8‐aryl‐8‐azaheptafulvenes 2 a, b providing cycloheptapyrroles 3 and 4 with metal carbene or ester functionality at C3. Moreover, consecutive cyclizationreactions are involved when enynyl carbenes are used. Thus, the cyclopenta[b]pyrrole
sequential treatment of an acetylide with a Fischercarbenecomplex and an alkene/diene yields alkynylcyclopropanes with a wide substitution range. The intramolecular process provides 1‐alkynylbicyclo[3.1.0]cyclohexanes by starting from 1,6‐enynes. A non‐heteroatom‐stabilized metal alkynylcarbene is responsible for the selectivetransfer of the propargylene unit.
patterns: Gold(I) catalyzes the conversion of cyclopentenes (1/1′) into cyclohexadienes (2/3). This profound skeleton rearrangement comprises ring expansion and a [1,2]‐alkynyl shift, and is thought to be initiated by the cleavage of the bridging CC bond. The proposed allyl–gold cation intermediate is trapped with alcohols to provide bicyclo[3.2.1]octadiene and tricyclo[3.2.1.02,7]octane derivatives.
A formal [4 + 2] heterocycloaddition of non-heteroatom-stabilized alkynyl carbenecomplexes and iminopyrroles is described. The reaction implies a totally regioselective synthesis of 6-azaindole derivatives through the formation of the pyridine ring. The mechanism of the reaction has been explored by means of density functional theory calculations, which showed a preference for the [4 + 2] cycloaddition
Unusual [1,2]- and [1,3]-M(CO)<sub>5</sub> Shifts in Fischer Carbene Complexes: [4 + 3] and [3 + 3] Annulation Reactions of Furan and Pyrrole Rings
作者:José Barluenga、Miguel Tomás、Eduardo Rubio、José A. López-Pelegrín、Santiago García-Granda、Mónica Pérez Priede
DOI:10.1021/ja983692o
日期:1999.4.1
The cycloadditionreactions of various C-heteroarylimines with α,β-unsaturated Fischercarbenecomplexes have been studied. Either [3 + 3] carbocyclization or [3 + 3] and [4 + 3] heterocyclization reactions were accomplished, depending on the structure of the imine and on the type of unsaturation of the carbenecomplex. Imines derived from furan-, 4, benzofuran-, 5, and N-methylindole-2-carboxaldehyde