Doran Robert, Guiry Patrick J
Centre for Synthesis and Chemical Biology, School of Chemistry and Chemical Biology, University College Dublin , Belfield, Dublin 4, Ireland.
J Org Chem. 2014 Oct 3;79(19):9112-24. doi: 10.1021/jo5014806. Epub 2014 Sep 18.
The catalytic asymmetric synthesis of a series of tertiary α-aryl cyclopentanones and cyclohexanones has been accomplished via a Pd-catalyzed decarboxylative protonation of the corresponding α-aryl-β-keto allyl esters. Enantioselectivities of up to 92% ee and 74% ee were achieved for cyclopentanone and cyclohexanone substrates, respectively. The route described gives access to these important structural motifs in moderate to high levels of enantioselectivity. In particular, this is only the second direct approach for the preparation of tertiary α-aryl cyclopentanones. The synthetic approach allows for simple modification of the aryl group. Significantly, substrates containing sterically hindered aryl groups gave the highest levels of enantioselectivity, and these aryl groups were readily installed by a Pb-mediated arylation of a β-keto allyl ester.
通过钯催化相应的α-芳基-β-酮烯丙基酯的脱羧质子化反应，实现了一系列叔α-芳基环戊酮和环己酮的催化不对称合成。环戊酮和环己酮底物的对映选择性分别高达92% ee和74% ee。所描述的路线能够以中等至高对映选择性水平获得这些重要的结构基序。特别地，这是制备叔α-芳基环戊酮的第二种直接方法。该合成方法允许对芳基进行简单修饰。值得注意的是，含有空间位阻芳基的底物具有最高水平的对映选择性，并且这些芳基可通过β-酮烯丙基酯的铅介导芳基化反应轻松引入。
