Chiral bicyclic guanidines: a concise and efficient aziridine-based synthesis

A series of chiral bicyclic guanidines, either symmetrical or non-symmetrical, were synthesized using a concise and efficient aziridine-based synthetic methodology. Starting from commercial amino alcohols, five synthetic steps were performed, with only three requiring chromatographic purification, giving the desired guanidines in 43-71% overall yield. Preliminary studies using these guanidines showed moderate enantioselectivity for several Michael reactions.