A chemoselective route which provides direct access to bicyclic tetramates, making use of Dieckmann cyclisation of functionalised oxazolidines and imidazolidines derived from an aminomalonate, is reported; calculations suggest that the observed chemoselectivity is kinetically controlled and leads to the thermodynamically most stable product. Some compounds in the library showed modest antibacterial activity against Gram-positive bacteria, and this activity is maximal in a well-defined region of chemical space (554 < Mw < 722 g mol-1; 5.78 < cLogP < 7.16; 788 < MSA < 972 Å2; 10.3 < rel. PSA < 19.08).