Concise synthesis of an enantiopure bicyclic pyrazinone as constrained peptidomimetic building blockElectronic supplementary information (ESI) available: Copies of the 1H and 13C NMR spectra of compounds 1, 2, 3, 4, 5 and 7. See DOI: 10.1039/c2ob06762e

A concise synthetic route has been developed for the preparation of a constrained peptidomimetic pyrazinone building block. From hydroxy- l -lysine, the desired pyrazinone is obtained in 43% overall yield (6 steps) via an efficient deprotectiondouble cyclization sequence. A concise synthetic route has been developed for the preparation of a constrained peptidomimetic pyrazinone building block.