acetic anhydride; triethylamine; 4-pyrrolidin-1-ylpyridine in dichloromethane 1 h; Ambient temperatureE/Z ratio= 5:2;

1: 2.) 1M HCl / 1.) SnCl4 / 1.) CH2Cl2, -78 deg C, 2 h 2.) -78 deg C to room temp. 2: 90 percent / Et3N, (CH3CO)2O / PPY / CH2Cl2 / 1 h / Ambient temperature; E/Z ratio= 5:2 View Scheme