Expeditious Approach to Pyrrolophenanthridones, Phenanthridines, and Benzo[c]phenanthridines via Organocatalytic Direct Biaryl-Coupling Promoted by Potassium tert-Butoxidet
Expeditious Approach to Pyrrolophenanthridones, Phenanthridines, and Benzo[c]phenanthridines via Organocatalytic Direct Biaryl-Coupling Promoted by Potassium tert-Butoxidet
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DOI：
10.1021/jo400890k
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发表时间：
2013-08-16
影响因子：
3.6
通讯作者：
Bisai, Alakesh
中科院分区：
文献类型：
--
作者：
De, Subhadip;Mishra, Sourabh;Bisai, Alakesh
在叔丁二氧化钾和有机分子作为催化剂的存在下，开发了一种涉及“无过渡金属”的邻卤- n -芳基苄胺分子内双芳基偶联的方法。该反应似乎是通过(KOBu)- bu -t促进的分子内均溶芳香取代（HAS）进行的。有趣的是，这种联芳基偶联在叔丁二氧化钾作为唯一启动子的情况下也起作用。在进一步扩展我们的方法时，我们发现n -酰基2-溴- n -芳基苄胺经过一锅n -去保护/联芳基偶联然后氧化，从而提供了一条快速的途径来获得菲菲啶和苯并[c]菲菲啶骨架。该策略已被应用于Amaryllidaceae生物碱的简明合成，即oxoassoanine (1b), anhydrolycorinone (1d), 5,6-二氢二氯乙烷（2d），三腓定（2b）和苯并[c]菲的生物碱二氢尼替丁（3b），二氢chelerythidine (3d)，二氢avicine (3f)，去尼替丁（3h）和去chelerythine （3j）。
A methodology involving a "transition metal-free" intramolecular biaryl-coupling of o-halo-N-arylbenzylamines has been developed in the presence of potassium tert-butoxide and an organic molecule as catalyst. The reaction appears to proceed through (KOBu)-Bu-t-promoted intramolecular homolytic aromatic substitution (HAS). Interestingly, this biaryl coupling also works in the presence of potassium tert-butoxide as sole promoter. On extending our approach further, we found that N-acyl 2-bromo-N-arylbenzylamines undergo a one-pot N-deprotection/biaryl coupling followed by oxidation, thus offering an expeditious route to the phenanthridine and benzo[c]phenanthridine skeletons. The strategy has been applied to a concise synthesis of Amaryllidaceae alkaloids viz. oxoassoanine (1b), anhydrolycorinone (1d), 5,6-dihydrobicolorine (2d), trispheridine (2b), and benzo[c]phenanthridines alkaloids dihydronitidine (3b), dihydrochelerythidine (3d), dihydroavicine (3f), nornitidine (3h), and norchelerythrine (3j).