General procedure for the syntheses of pentadienamides 2. A solution of freshly sublimated tBuOK (5 mmol, 560 mg, 2.5 equiv.) in THF (7 mL) was cooled to -78 °C. 1,1-Diethoxybut-2-ene (2 mmol, 288 mg) in THF (2 mL) and nBuLi (1.6 M in hexanes, 5 mmol, 3.13 mL) were added in quick succession and the mixture was stirred for 2 h during which time the temperature was raised to -40 °C. Afterwards the reaction was cooled back to -78 °C and the appropriate isocyanate (2.2 mmol) in THF (2 mL) was

more »

... After stirring the mixture at -78 °C for 2 h, a saturated NH 4 Cl solution (10 mL) was added. The resulting mixture was extracted with Et 2 O (3 x 10 mL), washed with water (10 mL) and brine (2 x 10 mL), and dried with anhydrous K 2 CO 3 . After filtration and evaporation of the solvent, the crude products were purified by flash column chromatography. General procedure for the syntheses of α-ketoamides derivatives 3. A solution of the appropriate pentadienamide (0.5 mmol) in CH 2 Cl 2 /MeOH (3 mL) was stirred in the presence of p-toluenesulfonic acid monohydrate (0.5 mmol, 95 mg, 1 equiv.) and the reaction progress monitored by TLC. After 0.5 h the reaction was complete, the reaction was quenched with water. After extraction with CH 2 Cl 2 (3 x 10 mL), the collected organic layers were washed with water (10 mL) and brine (2 x 10 mL), and dried with anhydrous K 2 CO 3 . After filtration and evaporation of the solvent, the crude products were purified by column flash chromatography. General procedure for the syntheses of N-aryl pyrrolidinones 4 and cyclic iminoethers 5. A 20-mL sealed tube fitted with a rubber septum cap and connected to a nitrogen filled balloon was charged with the appropriate pentadienamide (0.5 mmol) and cooled to 0°C. Then TFA (5 ml) was added dropwise, and the resulting mixture was stirred for 1 h. Afterwards the reaction was cooled back to 0 °C and a solution of NaOH (10%) was added, and the resulting mixture was extracted with several portions of Et 2 O. The combined organic layers were washed twice with NaHCO 3 , water and brine, and dried over anhydrous K 2 CO 3 . After filtration and evaporation of the solvent, the crude products were purified by column flash chromatography. Supplementary Material (ESI)