tert-butyl 7-(4-(ethoxycarbonyl)-4-methylpiperidin-1-yl)-5-oxa-2,6-diazaspiro[3.4]oct-6-ene-2-carboxylate 、
3,5-diethoxy-4-(1-methoxycyclobutyl)benzaldehyde 以the title compound was obtained in the similar manner as in Step G of Example 1的产率得到1-(2-(3,5-diethoxy-4-(1-methoxycyclobutyl)benzyl)-5-oxa-2,6-diazaspiro[3.4]oct-6-en-7-yl)-4-methylpiperidine-4-carboxylic acid