Efficient Microwave Assisted Syntheses of 2,5-Diketopiperazines in Aqueous Media

Aqueous in situ one-pot N-Boc-deprotection-cyclization of Nα-Boc-dipeptidyl-tert-butyl and methyl esters under microwave irradiation afforded 2,5-diketopiperazines (DKPs) in excellent yields. This protocol is rapid, safe, environmentally friendly, and highly efficient, and showed that the tert-butoxy moiety is also an excellent leaving group for these cyclizations.