n of P2 and amine capping structural elements provided inhibitors 4 and 38–50.
Scheme 3  Preparation of Hydroxymethylketone Derivatives
(i) 4 M HCl/dioxane, (ii) Boc-Leu-OH, HATU, NMM, DMF, 0 °C, (iii) HATU, 4-MeO-2-indolecarboxylic acid