Readily Available Unprotected Amino Aldehydes

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.