9-acetyl-2-(1-acetyl-2-oxo-1,2-dihydro-indol-3-ylidene)-2,9-dihydro-pyrano[2,3-
b]indole-4-carboxylic acid benzyl ester 在
chromium(VI) oxide 、
溶剂黄146 作用下,
生成
1'-acetyl-5,2'-dioxo-1',2'-dihydro-5H-spiro[furan-2,3'-indole]-3-carboxylic acid benzyl ester