Premium
Single and Consecutive Cyclization Reactions of Alkynyl Carbene Complexes and 8‐Azaheptafulvenes: Direct Access to Polycyclic Pyrrole and Indole Derivatives
Author(s) -
Barluenga José,
GarcíaRodríguez Jaime,
SuárezSobrino Ángel L.,
Tomás Miguel
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200901257
Subject(s) - carbene , indole test , chemistry , regioselectivity , pyrrole , adduct , reactivity (psychology) , medicinal chemistry , aryl , ring (chemistry) , stereochemistry , combinatorial chemistry , catalysis , organic chemistry , medicine , alkyl , alternative medicine , pathology
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 cyclization reactions are involved when enynyl carbenes are used. Thus, the cyclopenta[ b ]pyrrole framework 7 is formed by the consecutive [8+2] cyclization and cyclopentannulation reactions. The initially formed cyclopentannulation adduct can be intercepted through a Diels–Alder reaction with classic dienophiles to afford increasing structural complexity (compounds 8 and 9 ). More importantly, the construction of the indole skeleton is accomplished with a high degree of substitution and functionalization (compounds 11 – 15 ) by a one‐pot sequence that involves [8+2] cyclization, RNC or CO insertion, and ring closure.