Catalytic enantioselective intermolecular cycloadditions of 2-diazo-3,6-diketoester-derived carbonyl ylides with alkene dipolarophiles
Catalytic enantioselective intermolecular cycloadditions of 2-diazo-3,6-diketoester-derived carbonyl ylides with alkene dipolarophiles
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DOI：
10.1073/pnas.0307274101
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发表时间：
2004-04-13
影响因子：
11.1
通讯作者：
Redgrave, AJ
中科院分区：
文献类型：
--
作者：
Hodgson, DM;Bückl, T;Redgrave, AJ
催化级联反应能快速、对映选择性地产生复杂的分子结构，是不对称合成的一种有吸引力的方法。在本文中，手性铑催化剂显示，通过使用一系列的2-重氮基-3，6-二酮酯与双环[2.2.1]烯烃和苯乙烯作为反应伙伴来实现这样的转化。该反应可能通过从重氮化合物形成催化剂络合的羰基叶立德，然后与烯烃亲偶极试剂进行分子间环加成来进行。这是可能的，以获得高水平的不对称诱导[高达89%的对映体过量（ee）和92%ee的两个手性催化剂的研究]。对映体选择性是不是高度敏感的酮，形成叶立德的取代基变化，然而，分支确实提高ee. Observations的亲偶极体依赖的enantiofacial选择性在环加成表明，亲偶极体可以密切参与antirodiscrimination过程。
Catalyzed cascade reactions that generate molecular complexity rapidly and in an enantioselective manner are attractive methods for asymmetric synthesis. In the present article, chiral rhodium catalysts are shown to effect such a transformation by using a range of 2-diazo-3,6-diketoesters with bicyclo[2.2.1]alkenes and styrenes as reaction partners. The reactions are likely to proceed by formation of a catalyst-complexed carbonyl ylide from the diazo compound, followed by intermolecular cycloaddition with the alkene dipolarophile. It was possible to obtain high levels of asymmetric induction [up to 89% enantiomeric excess (ee) and 92% ee for the two chiral catalysts investigated]. Enantioselectivity is not highly sensitive to substituent variation at the ketone that forms the ylide; however, branching does improve ee. Observations of dipolarophile-dependent enantiofacial selectivity in the cycloadditions indicate that the dipolarophile can be intimately involved in the enantiodiscrimination process.