Addition of Alkynes to Aldehydes and Activated Ketones Catalyzed by Rhodium-Phosphine Complexes

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• 作者：Pawan K. Dhondi ; Patrick Carberry ; Lydia B. Choi ; John D. Chisholm
• 刊名：Journal of Organic Chemistry
• 出版年：2007
• 出版时间：December 7, 2007
• 年：2007
• 卷：72
• 期：25
• 页码：9590 - 9596
• 全文大小：176K
• 年卷期：v.72,no.25(December 7, 2007)
• ISSN：1520-6904

文摘

D=jo701643hn00001>A mixture of 2-(di-tert-butylphosphino)biphenyl and dicarbonylacetonato rhodium(I) provides an effectivecatalyst system for the addition of alkynes to aldehydes and activated ketones. In contrast to the morecommon 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 aldehydeswith an adjacent chirality center usually provides the Felkin addition product with excellent selectivityin some cases. Studies on the catalyst structure show that both the -diketonate and a carbon monoxideligand appear to be bound to the active catalyst. The use of chiral phosphines to induce asymmetry in thepropargyl alcohol products provided low enantioselectivity, which may be due to the phosphine havinga distal relationship to the reacting centers. Modification of other ligands, such as the -diketonate, appearsto be a more promising avenue for the development of an enantioselective variant.