A convenient and high yielding method to prepare a vast array of enantiomerically pure 3‐substituted diketopiperazines (3‐DKPs), bearing a benzyl protecting group on nitrogen 1 is reported. The methodology describes a simple one‐pot procedure, starting from readily available N‐protected L‐ or D‐amino acids employing the Ugi‐4CR in pure water, followed by a one‐step Boc‐deprotection and final lactamisation in acetic acid. All disubstituted DKPs were obtained in short times and isolated in excellent yields (84‐94%) by simple precipitation in water and subsequent filtration. The practical utility of this procedure proved efficient for the synthesis of cialis (Tadalafil) analogues.
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