synthetic acids possessing widely divergent structural features have been synthesized. Murinichloroethyl carbonate (27) esters of cephalotaxine are the most active of this group; this activity is less than that of harringtonine and other naturally occurring cephalotaxine esters. Other synthetic esters exhibiting activity are methyl cephalotaxylfumarate (4) and the trichloroethyl carbonate of cephalotaxyl-L-mandelate
合成了二十二种新的天然(-)-头孢他辛与具有广泛不同结构特征的合成酸的酯。头孢他辛的Murinichloroethylcarbonate(27)酯是这一组中最活跃的。该活性小于harringtonine和其他天然存在的头孢他辛酯的活性。表现出活性的其他合成酯是头孢
噻唑基
富马酸酯甲酯(4)和头孢
噻唑基-L-
扁桃酸酯的
碳酸三
氯乙基酯(21)。该实验肿瘤系统的特异性显然需要(-)-头孢他辛酯来抑制肿瘤,因为从头孢他辛的合成(+)对映异构体制备的头孢他酸甲酯(7b)没有活性。