Synthetic Photochemistry. XXXI. The Cycloaddition Reaction of Myrcene with 2,4-Dioxopentanoate : A Facile Synthesis of a Versatile Intermediate for Cycloneryl Derivatives

Abstract

Methyl 2,4-dioxopentanoate and myrcene smoothly afforded the photoadducts by irradiation with a high-pressure mercury lamp. The (2+2) rr adducts were selectively resulted from the conjugated double bond moiety. Reductive cyclization of the adduct afforded cycloneryl derivatives, whose further chemical conversion were carried out. Previously we have accomplished total syntheses of protoilludenes2' and some elemenoid sesquiterpenoids3' by means of the photocycloaddition of enolized B-diketone with appropriate olefins. Particularly, taking the advantage that the conjugated olefins are capable of forming photocycloadducts with 2,4-Dioxopentanoate (1), 3'`' we have carried out the photocycloaddition with isoprene (A) to efficiently construct the Cio-frameworks3•5' which were convertible to the correct head-to-tail monoterpenoid

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合成光化学。第三十一章。月桂烯与2,4-二氧戊酸酯的环加成反应:一种环基衍生物多用途中间体的简易合成

在高压汞灯照射下，2,4-二氧戊酸甲酯和月桂烯顺利地生成光合物。(2+2) rr加合物是由共轭双键部分选择性生成的。加合物的还原环化得到环酰衍生物，其进一步的化学转化进行。我们已经用烯醇化的b -二酮与适当的烯烃进行光环加成的方法合成了原酰二烯和一些类元素倍半萜类化合物。特别是，利用共轭烯烃能够与2,4-二氧戊酸酯(1,3’”)形成光环加合物的优势，我们与异戊二烯(A)进行了光环加成，有效地构建了可转换为正确的首尾单萜类化合物(环烯醚)和倍半萜类化合物(烯烯类化合物)骨架的cio -框架3•5’。从而为萜类化合物2 + hv H 02Me 1 3 02Me + 02Me 4 + 5的多用途c -同源化开辟了新途径

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