膦酰基乙酸甲酯二乙酯 、 6-[6,6-Dimethyl-4,8-dioxa-spiro[2.5]oct-(1E)-ylidene]-hexanal 在
sodium hydride 作用下,
生成 (E)-8-[6,6-Dimethyl-4,8-dioxa-spiro[2.5]oct-(1Z)-ylidene]-oct-2-enoic acid methyl ester 、
(E)-8-[6,6-Dimethyl-4,8-dioxa-spiro[2.5]oct-(1E)-ylidene]-oct-2-enoic acid methyl ester