Spirocyclic 3-pyrrolin-2-ones

Zang and Larock reported an interesting iodo-mediated ipso-cydizution of alkynyl carboxamides leading to give spirocyclic 3-pyrrolin-2-ones (Scheme 42 2005JA12230) this work built upon the earlier work of... 

The Tietz research group discovered a novel route from pyrroles to 3-pyrrohn-2-ones they treated a pyrrole-2-methanol with HCl and obtained the corresponding 3-pyrrohn-2-one derivative (1996S851). Couturier and coworkers investigated interesting reactions involving the conversion of 2,3-halopyrrole derivatives into spirocyclic 3-pyrrolin-2-ones under acidic conditions (2012BMCL6292). 

Stephenson and Tucker discovered an approach to fused 3-pyrrolin-2-ones via a tandem Ir-mediated radical cyclization and Cope rearrangement (Scheme 36 20110L5468). Treatment of cyclopropane-substituted propar-gylamide 170 with an iridium reagent and triethylamine led to the formation of fused 3-pyrrohn-2-one 172. The reaction manifold that explains the outcome of the reaction includes a radical cyclization to the spirocyclic intermediate 171, Cope rearrangement and re-aromatization. 

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