Use of 1, 8-diazabicyclo[5.4.0]undec-7-ene (DBU) in boiling xylene was found to be a convenient method for the retro-cycloaddition of adducts of 4-phenyl-1, 2, 4-triazolidine-3, 5-dione (PTAD) with steroidal 5, 7-dienes. This process was applied to the syntheses of ergosta-5, 7, 24(28)-trien-3β-ol and ergosta-5, 7, 22, 24(28)-tetraen-3β-ol.
在沸腾的二
甲苯中使用1, 8-二
氮杂双环[5.4.0]十一烯(
DBU)被发现是一种便捷的方法,用于4-苯基-1, 2, 4-
三氮唑-3, 5-二酮(
PTAD)与
固醇5, 7-二烯加合物的逆环加成。这一过程被应用于合成ergosta-5, 7, 24(28)-
三烯-3β-醇和ergosta-5, 7, 22, 24(28)-四烯-3β-醇。