1',3'-dihydro-1'-ethanol-3',3'-dimethyl-8-methoxy-6-nitro-spiro(2H-1-benzopyran-2',2'-(2H)-indole) 、 alkaline earth salt of/the/ methylsulfuric acid 以55%的产率得到2-methyl-acrylic acid 2-(8-methoxy-3',3'-dimethyl-6-nitro-3'
H-spiro[chromene-2,2'-indol]-1'-yl)-ethyl ester