... 1473 J. Heterocyclic Chem., 32, 1473 (1995). ... Dry solvents and commercial compounds were obtained from Aldrich Chemical Co ... solid which could be recrystallizcd from methanol, mp 253-255°; 'H nmr (400 MHz, deuteriochloroform): 8 7.72 (d, J = 2.8 Hz, 1-H), 6.27 (d, J = 2.8 Hz ...