Synthesis of cycloheptanoids through catalytic enantioselective (4 + 3)-cycloadditions of 2-aminoallyl cations with dienol silyl ethers
Synthesis of cycloheptanoids through catalytic enantioselective (4 + 3)-cycloadditions of 2-aminoallyl cations with dienol silyl ethers
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通过 2-氨基烯丙基阳离子与二烯醇甲硅烷基醚的催化对映选择性 (4--3)-环加成合成环庚烷类化合物
DOI：
10.1038/s44160-022-00150-0
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发表时间：
2022-09
期刊：
影响因子：
--
通讯作者：
Weiwei Zi
中科院分区：
文献类型：
--
作者：
Lulu Shen;Zitong Lin;Bin Guo;Weiwei Zi
由于所需的两性离子三碳单元的不稳定性，涉及三碳单元（n + 3）的对映选择性环加成反应的开发是具有挑战性的。由于天然产物中奇数碳环基序的普遍存在，这些两性离子物种的反应性特别有趣。虽然与2-氧烯丙基阳离子的环加成反应通常很发达，但与2-氨基烯丙基阳离子的环加成反应很少，催化实例仅限于涉及呋喃衍生物的分子内反应。在这里，我们报告了一种方法，铜催化形成2-氨基烯丙基阳离子乙炔基亚甲基环氨基甲酸酯和随后的对映选择性（4 + 3）-环加成反应之间的2-氨基烯丙基阳离子和二烯醇硅醚。七元环碳环产物以良好的产率和高的对映体控制形成。反应产物的合成效用已通过一系列的还原，交叉偶联和环化转化得到证实。机理研究表明，该反应涉及双核铜催化剂，并逐步进行，与第二个C-C键的形成作为周转限制步骤。由于所需的两性离子三碳组分的不稳定性，通过（4 + 3）-环加成反应合成七元碳环通常具有挑战性。现在，铜催化的2-氨基阳离子与二烯醇硅醚的（4 + 3）-环加成反应被报道，以良好的产率和优异的对映体控制提供了七元碳环。
Development of enantioselective cycloaddition reactions involving three-carbon units (n + 3) is challenging because of the instability of the required zwitterionic three-carbon units. The reactivity of these zwitterionic species is particularly intriguing due to the prevalence of odd-numbered carbocyclic ring motifs in natural products. Although cycloadditions with 2-oxyallyl cations are generally well developed, cycloadditions are rare with 2-aminoallyl cations, with catalytic examples limited to intramolecular reactions involving furan derivatives. Here we report a method for copper-catalysed formation of 2-aminoallyl cations from ethynyl methylene cyclic carbamates and subsequent enantioselective (4 + 3)-cycloaddition reactions between 2-aminoallyl cations and dienol silyl ethers. The seven-membered ring carbocyclic products are formed in good yields and with high enantiocontrol. The synthetic utility of the reaction products has been demonstrated through a series of reductive, cross-coupling and cyclization transformations. Mechanistic studies reveal that the reaction involves a dinuclear copper catalyst and occurs stepwise, with formation of the second C–C bond as the turnover-limiting step. Synthesis of seven-membered carbocycles via (4 + 3)-cycloaddition reactions is often challenging due to the instability of the zwitterionic three-carbon component required. Now, a copper-catalysed enantioselective (4 + 3)-cycloaddition of 2-amino cations with dienol silyl ethers is reported, providing seven-membered carbocycles in good yields and with excellent enantiocontrol.
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作者：
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