We report a new class of bench-stable compounds that contain seemingly incompatible functional groups: an aldehyde and an unprotected secondary amine. The thermodynamic driving force to undergo condensation between these two functionalities is offset by a high barrier imposed on this process by the aziridine ring strain. The resulting amino aldehydes exist as dimers and in the solid state. They are stable to epimerization and contain two orthogonal reaction centers, namely, an amine/aziridine and an aldehyde. Their ability to act as linchpins has been evaluated in complex heterocycle synthesis. For instance, pentacyclic frameworks can be made in one simple operation using N-benzyltryptamine as the reaction partner. Construction of other molecular skeletons with minimal use of protecting group manipulations should be feasible.
Unprotected Vinyl Aziridines: Facile Synthesis and Cascade Transformations
作者:Sivaraj Baktharaman、Nicholas Afagh、Adelle Vandersteen、Andrei K. Yudin
DOI:10.1021/ol902550q
日期:2010.1.15
have led to the construction of a variety of stereochemically rich heterobicycles. A cascade ring-opening/ring-contraction mechanism operates in the course of the process. These results underscore the notion that interesting and useful nitrogen-mediated relay processes can arise when elements of strain are merged with the manifolds of enamine/iminium ion reactivity.
Skeletal Fusion of Small Heterocycles with Amphoteric Molecules
作者:Lawrence L. W. Cheung、Zhi He、Shannon M. Decker、Andrei K. Yudin
DOI:10.1002/anie.201106024
日期:2011.12.2
three contiguous stereocenters was prepared from a [3+2] annulation involving amphoteric aziridine aldehydes and isocyanates and further converted to a series of densely functionalized hetercycles, which are difficult to synthesize using established methods. The results highlight the potential of (1,3) amphotericmolecules to construct heterocyclic scaffolds using trivial starting materials.