... Tetrahedron Letters. Volume 40, Issue 29, 16 July 1999, Pages 5295–5299. ... This letter describes novel high-yielding solution phase preparations of 1,4-benzodiazepine-2,5-dione, diketo-piperazine, ketopiperazine and dihydroquinoxalinone libraries via a UDC (Ugi/de-Boc ...