... The product was purified by evaporative distillation to give 5.0 g of 5 as a yellow oil which slowly solidified mp 26-27 OC; 'H NMR (CDCl,) 6.38 (d, J = 4, 1 H), 5.93 (b, 1 H), 5.47-4.43 (m, 3 H), 2.1 (s, 3 H). Anal. ... Yu-Fen Zhao,* She-Kang Xi, Ai-Teng Song, and Gai-Jiao Ji ...