Fig. 2: Optimization of deconstruction of the pyrrolidines.
From: Synthesis of dienes from pyrrolidines using skeletal modification
a Optimization of deconstruction of the pyrrolidine (1a) using N3SO2N3. b One-pot synthetic procedure developed using imidazolium sulfonyl azide. c Complete stereoselective synthesis of diene isomers (2b vs 3b). SC-I: (i) pyrrolidine (0.2 mmol), DBU (0.4 mmol), N3SO2N3 (0.2 M in DCM, 3.0 mL), DCM (0.5 mL), rt, 3 h; (ii) tBuOLi (1.0 equiv), DCE (2 mL), 120 °C, 3 h, isolated yield of diene based on pyrrolidine. SC-II: pyrrolidine (0.2 mmol), imidazolium sulfonyl azide (0.21 mmol), CH3CN (2.0 mL), 0 °C, 3 h; Removing most of CH3CN in vacuo, then tBuOLi (0.2 mmol), DCE (2 mL), 120 °C, 3 h, isolated yield based on pyrrolidine.
