Herein we describe compositions and methods for the synthesis of [2.2.2]-diazabicyclic structures comprising a domino reaction sequence involving aldol condensation, alkene isomerization, and intramolecular hetero-Diels-Alder cycloaddition. Excellent diastereofacial control during the cycloaddition is enforced with a removable chiral phenyl aminal diketopiperazine substituent. The reaction sequence rapidly generates molecular complexity and is competent with both enolizable and non-enolizable aldehyde substrates. This method provides an efficient route to [2.2.2]-diazabicyclic structures, common to bioactive prenylated indole alkaloids such as the brevianamides and stephacidins.
Synthesis of 2-Pyridones by Cycloreversion of [2.2.2]- Bicycloalkene Diketopiperazines
作者:Kaila A. Margrey、Amy D. Hazzard、Jonathan R. Scheerer
DOI:10.1021/ol403632t
日期:2014.2.7
5-diketopiperazine (DKP) derivatives, is compatible with both aromatic and aliphatic aldehyde components, and can intercept either intra- or intermolecular cycloaddition manifolds. Priming of one aza-bridging function in the intermediate [2.2.2]-DKP scaffold permits cycloreversion (microwave heating) and selective extrusion of cyanate derivatives leading to the formation of 2-pyridone structures. Progress