Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5228727 | Tetrahedron | 2008 | 10 Pages |
A survey of conditions for the palladium catalyzed intramolecular Heck cyclization of protected amines has shown that the Herrmann-Beller palladacycle can be exploited under 'cationic' conditions to provide a robust and rapid route (<2 h) to the synthesis of single double bond isomer phenanthridines in excellent yield (76-99%). In addition, the same cyclization can be performed under 'neutral' conditions to provide phenanthridines with a double bond isomer profile suitable for exploitation in diversity-based applications. We have also shown that the highly reactive (tBu3P)2Pd catalyst can induce cyclization at low temperatures (â¤50 °C), giving similar results to the 'neutral' conditions, and offering an alternative pathway for sensitive substrates.
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