A method for the synthesis of both symmetric and asymmetric fused spiro[4.4]-nonane-dione derivatives has been developed. It is based on a Diels–Alder reaction of spiro[4.4]nona-2,7-diene-1,6-dione as a dienophile component followed by immediate aromatization of the adduct. An active diene component can be generated using the tetrabromoxylene/NaI system, the 1,3-diphenylisobenzofuran/BF₃ system, or substituted cyclones.

中文翻译：

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通过串联 [4 + 2]-环加成/芳构化反应构建环状螺[4.4]-壬烷二酮

开发了一种合成对称和不对称稠合螺[4.4]-壬烷二酮衍生物的方法。它基于螺[4.4]nona-2,7-二烯-1,6-二酮作为亲二烯体组分的狄尔斯-阿尔德反应，然后立即对加合物进行芳构化。活性二烯组分可以使用四溴二甲苯/NaI体系、1,3-二苯基异苯并呋喃/BF ₃体系或取代旋风分离器来产生。