Divergent synthesis of 2,3-dihydro-1H-pyrroles, 3-alkyl-1H-pyrroles and 3-alkenyl-1H-pyrroles from 2,4-pentadienenitriles and isocyanidesElectronic supplementary information (ESI) available: Copies of NMR spectra for compounds 2-4. CCDC 968815 and 968816. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4ob00912f

An efficient and divergent one-pot synthesis of 2,3-dihydro-1 H -pyrroles, 3-alkyl-1 H -pyrroles and 3-alkenyl-1 H -pyrroles from readily accessible 2,4-pentadienenitriles with isocyanide based on reaction condition selection has been described. The reaction of 2,4-pentadienenitriles with ethyl isocyanoacetate undergoes a formal [2 + 3] annulation either to generate 2,3-dihydro-1 H -pyrroles in the presence of DBU (0.3 equiv.) in EtOH at room temperature or to give 3-alkyl-1 H -pyrroles in the presence of DBU (2.0 equiv.) in EtOH under reflux. Moreover, the 2,3-dihydro-1 H -pyrroles could be converted to 3-alkenyl-1 H -pyrroles with DDQ as an oxidant. A facile and divergent synthesis of 2,3-dihydro-1 H -pyrroles, 3-alkyl-1 H -pyrroles and 3-alkenyl-1 H -pyrroles has been developed via a formal [2 + 3] annulation of 2,4-penta-dienenitriles and ethyl isocyanoacetate by the variation of reaction conditions.