18-crown-6 ether in ethylene glycol dimethyl ether; dimethyl sulfoxide T=0°C; 1 h; Yields of byproduct given;

1H-imidazole; 4-(N,N-dimethlyamino)pyridine; 18-crown-6 ether 1) DMSO, DME, 0 deg C, 1 h; 2) DMF, r.t., 48 h; Yield given. Multistep reaction. Yields of byproduct given;