anhydride may be visualized as a C-acylation of the β-dicarbonyl component followed by an intramolecular condensation in a Michael manner, forming a substituted furan which acts as diene in a Diels-Alder reaction with maleic anhydride. Hydrogenation and subsequent degradation of the adduct gives a furan derivative, 4-carboxy-5-methyl-2-furyl acetic acid (C8H8O5), very similar to the proposed furan intermediate
乙酰丙酮或
乙酰乙酸乙酯和
马来酸酐之间的2:1加合物的形成可以可视化为β-二羰基组分的C-酰化,然后以迈克尔方式分子内缩合,形成取代的
呋喃,该取代的
呋喃在Diels中起二烯的作用-与
马来酸酐的Al醛反应。加合物的氢化和随后的降解得到
呋喃衍
生物4-羧基-5-甲基-
2-呋喃乙酸(C 8 H 8 O 5),与拟议的
呋喃中间体非常相似。给出并讨论了支持拟议结构的PMR光谱。