Pyrrole direct coupling with carbonyl compounds

Although conceptually similar, the direct coupling of carbonyl compounds with pyrroles (Scheme 141) using a Cu(ii) oxidant probably differs mechanistically from the intramolecular cyclization of pyrrole 718 to 2,3-dihydro-l//-pyrrolizine 719 (in 65% yield as a 4.5 1 mixture of diastereomers) using Fe(lll)-based oxidant (ferrocenium hexa-fluorophosphate) (Scheme 142) <2006ARK310>. 

Applying the strategy of direct coupling of pyrroles with carbonyl compounds, Baran et al. developed a short enantioselective synthesis of (5)-ketorolac, Syntex s analgesic and anti-inflammatory agent.The antipode of ketorolac is more potent and causes fewer side effects. 

Baran PS, Richter JM, Lin DW (2005) Direct coupling of pyrroles with carbonyl compounds short enantioselective synthesis of (S)-ketorolac. Angew Chem Int Ed 44 609-612... 

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