Abstract

Robinson-type cyclopentannulations of cyclic β-oxoesters possessing a 1,4-diketone moiety are accomplished under four different Brønsted basic reaction conditions. Using pyrrolidine/acetic acid in DMSO, an oxohexahydrocyclopenta[a]indene (42%) and an N-Boc-protected oxohexahydrocyclopenta[c]pyridine derivative (62%) are obtained with retention of the ester moieties. The latter compound defines an interesting new scaffold for medicinal chemistry with three positions allowing further derivatizations. The use of KOtBu in DMSO or NaH in toluene leads to cyclopentene derivatives with either partial ester saponification and decarboxylation or displacement of the ester moiety within the carbon skeleton. With aqueous KOH, the cyclopentannulations are successful in almost all cases, but with the ester moieties cleaved off. The respective bicyclic and tricyclic products are obtained in good to excellent yields. The 1,4-diketone starting materials are prepared by cerium-catalyzed oxidative coupling of β-oxoesters with isopropenyl acetate. Alternatively, a two-step sequence consisting of α-propargylation followed by palladium-catalyzed alkyne hydration is used.

Robinson-type cyclopentannulations of cyclic β-oxoesters possessing a 1,4-diketone moiety are accomplished under four different Brønsted basic reaction conditions. Using pyrrolidine/acetic acid in DMSO, an oxohexahydrocyclopenta[a]indene (42%) and an N-Boc-protected oxohexahydrocyclopenta[c]pyridine derivative (62%) are obtained with retention of the ester moieties. The latter compound defines an interesting new scaffold for medicinal chemistry with three positions allowing further derivatizations. The use of KOtBu in DMSO or NaH in toluene leads to cyclopentene derivatives with either partial ester saponification and decarboxylation or displacement of the ester moiety within the carbon skeleton. With aqueous KOH, the cyclopentannulations are successful in almost all cases, but with the ester moieties cleaved off. The respective bicyclic and tricyclic products are obtained in good to excellent yields. The 1,4-diketone starting materials are prepared by cerium-catalyzed oxidative coupling of β-oxoesters with isopropenyl acetate. Alternatively, a two-step sequence consisting of α-propargylation followed by palladium-catalyzed alkyne hydration is used.

中文翻译：

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含1，4-二酮部分的环状β-氧代酯的Robinson型环化形成双环环戊烯酮衍生物

摘要

在四个不同的布朗斯台德碱性反应条件下，完成具有1,4-二酮部分的环状β-氧代酯的Robinson型环戊环化反应。在DMSO中使用吡咯烷/乙酸，在保留酯部分的情况下获得了氧代六氢环戊[ a ]茚（42％）和N -Boc保护的氧代六氢环戊[ c ]吡啶衍生物（62％）。后者化合物定义了一种有趣的药物化学新支架，具有三个位置，可以进一步衍生化。KO t的使用DMSO中的Bu或甲苯中的NaH导致环戊烯衍生物的酯部分皂化和脱羧或碳骨架内酯部分的置换。使用KOH水溶液，几乎在所有情况下都可以成功进行环戊环化反应，但是酯部分会被裂解。以良好或优异的产率获得了相应的双环和三环产物。1，4-二酮原料是通过铈催化β-氧代酯与乙酸异丙烯酯的氧化偶联而制得的。可替代地，使用由α-炔丙基化然后钯催化的炔烃水合组成的两步​​序列。

在四个不同的布朗斯台德碱性反应条件下，完成具有1,4-二酮部分的环状β-氧代酯的Robinson型环戊环化反应。在DMSO中使用吡咯烷/乙酸，在保留酯部分的情况下获得了氧代六氢环戊[ a ]茚（42％）和N -Boc保护的氧代六氢环戊[ c ]吡啶衍生物（62％）。后者化合物定义了一种有趣的药物化学新支架，具有三个位置，可以进一步衍生化。KO t的使用DMSO中的Bu或甲苯中的NaH导致环戊烯衍生物的酯部分皂化和脱羧或碳骨架内酯部分的置换。使用KOH水溶液，几乎在所有情况下都可以成功进行环戊环化反应，但是酯部分会被裂解。以良好或优异的产率获得了相应的双环和三环产物。1，4-二酮原料是通过铈催化β-氧代酯与乙酸异丙烯酯的氧化偶联而制得的。可替代地，使用由α-炔丙基化然后钯催化的炔烃水合组成的两步​​序列。