A serendipitous one-pot synthesis of the octahydro-2-pyrazino[1,2-]pyrazine core.

An unexpected nitro group displacement during a nitro-Mannich reaction led to the one-pot formation of the octahydro-2-pyrazino[1,2-]pyrazine core, representing the shortest access to date to this pharmacologically relevant heterobicyclic system. A mechanistic hypothesis is suggested and supported by specific experiments and HRMS analysis of reaction mixtures.

Native State Organization of Outer Membrane Porins Unraveled by HDx-MS.

Hydrogen-deuterium exchange (HDx) associated with mass spectrometry (MS) is emerging as a powerful tool to provide conformational information about membrane proteins. Unfortunately, as for X-ray diffraction and NMR, HDx performed on reconstituted in vitro systems might not always reflect the in vivo environment. Outer-membrane vesicles naturally released by Escherichia coli were used to carry out analysis of native OmpF through HDx-MS.