Intramolecular Hetero Diels−Alder (Povarov) Approach to the Synthesis of the Alkaloids Luotonin A and Camptothecin
摘要:
Pyrrolo[3,4-b]quinolines can be formed through the coupling of anilines with N-propargylic substituted heterocyclic aldehydes in the presence of mild Lewis acid catalysts (Ln(OTf)(3)). The coupling proceeds through sequential imine formation and a formal intramolecular aza-Diels-Alder (Povarov) reaction. This approach was applied in a total synthesis of luotonin A and a formal synthesis of camptothecin.
Intramolecular Hetero Diels−Alder (Povarov) Approach to the Synthesis of the Alkaloids Luotonin A and Camptothecin
作者:Heather Twin、Robert A. Batey
DOI:10.1021/ol0479848
日期:2004.12.1
Pyrrolo[3,4-b]quinolines can be formed through the coupling of anilines with N-propargylic substituted heterocyclic aldehydes in the presence of mild Lewis acid catalysts (Ln(OTf)(3)). The coupling proceeds through sequential imine formation and a formal intramolecular aza-Diels-Alder (Povarov) reaction. This approach was applied in a total synthesis of luotonin A and a formal synthesis of camptothecin.
FeCl<sub>3</sub>/KI‐Catalyzed Tandem Oxidative Cyclization for Switchable Total Synthesis of Luotonin A, B and Derivatives
A totalsynthesis strategy was developed for the synthesis of luotonin A, B and their analogues using synergistic FeCl3/KI-catalyzed oxidative cyclization. This protocol utilizes cheap and widely available N-propargyl 2-methyl-quinazolinones and arylamines under mild conditions, and it has a wide substrate scope and high atom economy. Different natural products (luotonin A, B and derivatives) can be