Macrocycle formation by catalytic intramolecular cyclopropanation. A new general methodology for the synthesis of macrolides
Macrocycle formation by catalytic intramolecular cyclopropanation. A new general methodology for the synthesis of macrolides
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DOI：
10.1021/ja971687z
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发表时间：
1997-09-24
影响因子：
15
通讯作者：
Lynch, V
中科院分区：
文献类型：
--
作者：
Doyle, MP;Peterson, CS;Lynch, V
当近端烯丙基和远端烯烃环丙烷之间存在竞争时，亲电性增强的催化剂：Rh-2(pfb)(4) > Rh-2(OAc)4、Cu(MeCN)(4)PF6 > Rh(cap)(4)和Cu(acac)(2)有利于大环丙烷化。萜烯体系、顺式神经酰基重氮乙酸酯及其相关结构、丙二酸酯衍生物，以及具有1,2-苯二甲醇、季戊四醇和顺式2-丁烯-1,4-二醇连接物的体系，都能在最远的碳-碳双键上进行环丙烷化，产率很高。一般来说，只观察到一种环丙烷非对映异构体，但环尺寸的增加使得大环化反应中的立体化学类似于分子间环丙烷化反应。在一种体系（25）中，大环加成伴随着环内酯的形成/[2,3]-异位重排导致形成10元环内酯。总的来说，对大周期形成的限制很少，而且该方法似乎具有普遍的适用性。
Catalytic intramolecular cyclopropanation by diazoacetates onto a remote carbon-carbon double bond resulting in the formation of 9- to 20-membered ring lactones is reported, When competition exists between proximal allylic and remote olefinic cyclopropanation, macrocyclization is favored by catalysts of increasing electrophilicity: Rh-2(pfb)(4) > Rh-2(OAc)4, Cu(MeCN)(4)PF6 > Rh(cap)(4), and Cu(acac)(2). Terpene systems, cis-nerolidyl diazoacetate and related structures, malonic ester derivatives, and those with 1,2-benzenedimethanol, pentaerythritol, and cis-2-buten-1,4-diol linkers all undergo cyclopropanation onto the most remote carbon-carbon double bond in good yield. Generally, only one cyclopropane diastereoisomer is observed, but increasing ring size allows stereochemistries in macrocyclization reactions that resemble those of their intermolecular cyclopropanation counterparts. In one system (25) macrocyclic addition is accompanied by ylide formation/[2,3]-sigmatropic rearrangement resulting in the formation of a 10-membered ring lactone. Overall, few limits to macrocycle formation are evident, and the methodology appears to have general applicability.