Enantioselective Ficini reaction: ruthenium/PNNP-catalyzed [2+2] cycloaddition of ynamides with cyclic enones.
Enantioselective Ficini reaction: ruthenium/PNNP-catalyzed [2+2] cycloaddition of ynamides with cyclic enones.
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DOI：
10.1002/anie.201007753
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发表时间：
2011-03
影响因子：
--
通讯作者：
C. Schotes;A. Mezzetti
中科院分区：
文献类型：
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作者：
C. Schotes;A. Mezzetti
最近的合成进展已经将氰化物变成了反应活性可以微调的广泛可用的底物。尤其是，酰胺与炔基溴化物的交叉偶联为广泛取代的氰化物提供了广泛的途径。[2]因此，在过去的几年中，它们在有机化学中的使用激增，这些化合物经历了α或β位置的加成、氧化或还原偶合、氧化、闭环歧化、环异构化和环加成反应。[1]虽然已经报道了大量的新的转化，但与氰胺的立体选择性反应，特别是不对称反应，[3]亚胺的直接应用是Ficini反应，其最初的版本是热驱动的，与环烯酮的[2+2]环加成反应(方案1)。[4]在Ficini反应中使用亚胺来代替亚胺的优点是，吸电子基团降低了三键的反应性。这种反应性的下降抑制了热反应，并允许采用催化方法，特别是对映选择性反应。尽管这是一个直截了当的发展，但第一个月桂胺与烯酮的催化反应的例子最近才被报道。[5]这些组合的AgI/CuII催化剂的性能一般，在氮原子上带有手性辅助的月桂胺产生了1：1的非对映异构体混合物。一般来说，[2+2]与氰胺的环加成反应很少见，而手性助剂
Recent synthetic advances have turned ynamides into broadly available substrates whose reactivity can be finely tuned.[1] In particular, the cross-coupling of amides with alkynyl bromides gives broad access to widely substituted ynamides.[2] Thus, the last few years have witnessed a surge of their use as nitrogen-containing building blocks in organic chemistry that undergo addition at the α or β positions, oxidative or reductive coupling, oxidation, ring-closing metathesis, cycloisomerization, and cycloaddition reactions.[1] Although a vast number of new transformations have been reported, stereoselective reactions with ynamides, and in particular enantioselective ones, are still rare.[3] A straightforward application of ynamides is the Ficini reaction, whose original version is a thermally driven, stepwise [2+ 2] cycloaddition of an ynamine with a cyclic enone (Scheme 1).[4]The advantage of using ynamides in the Ficini reaction instead on ynamines is that the electron-withdrawing group decreases the reactivity of the triple bond. This decrease in reactivity inhibits the thermal reaction and allows for a catalytic approach, and in particular for enantioselective reactions. Despite this being a straightforward development, the first example of a catalytic reaction of ynamides with enones was reported only very recently.[5] The performance of these combined AgI/CuII catalysts is modest, though, and an ynamide bearing a chiral auxiliary on the nitrogen atom gave 1: 1 diastereomeric mixture. In general,[2+ 2] cycloaddition reactions with ynamides are rare, and chiral auxiliaries on the