Addition of alkynes to aldehydes and activated ketones catalyzed by rhodium-phosphine complexes
Addition of alkynes to aldehydes and activated ketones catalyzed by rhodium-phosphine complexes
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DOI：
10.1021/jo701643h
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发表时间：
2007-12-07
影响因子：
3.6
通讯作者：
Chishohm, John D.
中科院分区：
文献类型：
--
作者：
Dhondi, Pawan K.;Carberry, Patrick;Chishohm, John D.
[图片]2-（二叔丁基膦）联苯和二羰基丙酮铑(I)的混合物提供了一种有效的催化剂体系，用于将炔添加到醛和活性酮中。与更常见的锌催化过程相反，可烯化的1,2-二羰基是这些铑催化添加物的优良底物。该反应允许在温和的条件下生成丙炔醇，可以耐受许多与其他方法不相容的官能团（如羧酸）。对于不对称的1,2-二酮，选择性很小。在某些情况下，具有相邻手性中心的醛与炔的加成反应通常提供具有极好选择性的费尔金加成产物。对催化剂结构的研究表明-二酮酸酯和一氧化碳配体似乎都与活性催化剂结合。使用手性膦诱导丙炔醇产物的不对称性提供了较低的对映选择性，这可能是由于膦与反应中心的关系较远。其他配体的修饰，如β -二酮酸酯，似乎是一个更有前途的途径，为发展对映选择性变体。
[GRAPHICS]A mixture of 2-(di-tert-butylphosphino)biphenyl and dicarbonylacetonato rhodium(I) provides an effective catalyst system for the addition of alkynes to aldehydes and activated ketones. In contrast to the more common zinc-catalyzed processes, enolizable 1,2-dicarbonyls are excellent substrates for these rhodium-catalyzed additions. This reaction allows for the formation of propargylic alcohols under mild conditions, tolerating many functional groups (such as carboxylic acids) that are incompatible with other methods. Little selectivity was observed in cases of unsymmetrical 1,2-diketones. Addition of alkynes to aldehydes with an adjacent chirality center usually provides the Felkin addition product with excellent selectivity in some cases. Studies on the catalyst structure show that both the beta-diketonate and a carbon monoxide ligand appear to be bound to the active catalyst. The use of chiral phosphines to induce asymmetry in the propargyl alcohol products provided low enantioselectivity, which may be due to the phosphine having a distal relationship to the reacting centers. Modification of other ligands, such as the beta-diketonate, appears to be a more promising avenue for the development of an enantioselective variant.