Enhancement of 5-Aminopenta-2,4-dienals Electrophilicity via Activation by <i>O</i>,<i>N</i>-Bistrifluoroacetylation. Application to an <i>N</i>-Acyl Pictet−Spengler Reaction
作者:Philippe Nuhant、Sanjay B. Raikar、Jean-Charles Wypych、Bernard Delpech、Christian Marazano
DOI:10.1021/jo9019545
日期:2009.12.18
tetrahydro-β-carbolines and tetrahydroisoquinolines bearing an enal function. In this N-acyl Pictet−Spengler reaction the electrophilicity of the aminopentadienals was dramatically increased by O,N-bistrifluoroacetylation. Recovery of the nitrogen nucleophilicity was achieved using a reductive process, and the heterocyclic amines were converted into aminonitriles by a Strecker reaction in the presence of butanal
用三氟乙酸酐处理由色胺或高藜芦胺与戊二醛缩合得到的氨基戊二烯醛,从而形成具有烯醇功能的四氢-β-咔啉和四氢异喹啉。在此N-酰基Pictet-Spengler反应中,O,N使氨基戊二烯醛的亲电性急剧增加-双三氟乙酰化。使用还原过程实现了氮亲核性的恢复,并且在丁醛存在下通过Strecker反应将杂环胺转化为氨基腈。在三氟甲磺酸锌存在下并通过氰化物离子捕获,通过分子内迈克尔将原位生成的烯胺加到烯部分上来实现环化。以这种方式,获得了与原美托美汀和二氢甲氧萘啶有关的化合物,并且还原步骤导致(±)-美托美诺的短合成。