8,8,9,10,10-pentamethyl-1,5-dioxa-9-azaspiro-[5.5]undecane-3,3-dicarboxylic acid, diethyl ester 、
1,4-环己烷二甲醇 、 1,5-dioxa-3,3-bis(ethoxycarbonyl)-8,8,10,10-tetramethyl-9-azaspiro<5.5>undecane 以72%的产率得到8,8,9,10,10-Pentamethyl-1,5-dioxa-9-azaspiro-[5.5]undecane-3,3-dicarboxylic acid