2-[2-(1-Benzenesulfonyl-1H-indol-3-yl)-1-hydroxy-2-methoxycarbonyl-ethyl]-1-(4-methoxy-benzyl)-1H-indole-3-carboxylic acid 在
草酰氯 、 titanium(III) chloride 、
silica gel 作用下,
以35%的产率得到Methyl 21-(benzenesulfonyl)-10-[(4-methoxyphenyl)methyl]-2-oxo-10,21-diazapentacyclo[12.7.0.03,11.04,9.015,20]henicosa-1(14),3(11),4,6,8,12,15,17,19-nonaene-13-carboxylate