Large, diverse compound libraries are an essential requisite in target-based drug development. In this work, a robust microwave-assisted synthesis for the diastereoselective generation of 3-saccharinyltrans-b-lactams is reported. The method is optimised for combinatorial library synthesis in which decoration of the scaffold is varied on both the b-lactam and the saccharine moiety. Within the European Lead Factory (ELF) consortium, a library of 263 compounds was efficiently produced using the developed methodology.