Inhibition of human neutrophil elastase. 4. Design, synthesis, X-ray crystallographic analysis, and structure-activity relationships for a series of P2-modified, orally active peptidyl pentafluoroethyl ketones.

A series of P2-modified, orally active peptidic inhibitors of human neutrophil elastase (HNE) are reported. These pentafluoroethyl ketone-based inhibitors were designed using pentafluoroethyl ketone 1 as a model. Rational structural modifications were made at the P3, P2, and activating group (AG) portions of 1 based on structure-activity relationships (SAR) developed from in vitro (measured Ki) data and information provided by modeling studies that docked inhibitor 1 into the active site of HNE. The modeling-based design was corroborated with X-ray crystallographic analysis of the complex between 1 and porcine pancreatic elastase (PPE) and subsequently the complex between 1 and HNE.

Synthesis of cbz-protected ketomethylene dipeptide isosteres.

Ketomethylene peptide isosteres have been the focus of a variety of synthetic studies because of their potential as therapeutic agents in the treatment of medical conditions mediated by proteases (1-3). The dipeptide core units 1 are chemically characterized by a 1,4-disposition of the carbonyl groups (ketone and carboxylate) and have an alkyl group at C-2 that is a chiral center. Protecting groups at amino nitrogen (typically carbamate such as Cbz or Boc) and the carboxyl group (typically ester) are usually present to make processing easier but must be readily and independently removable to permit extension in either the N-terminal or C-terminal directions (Fig. 1). Figure 1.

Highly stereoselective synthesis of anti-N-protected-alpha-amino epoxides.

A simple and efficient method for the synthesis of anti-N-protected amino epoxides from carbamate-protected amino acids is described. The two key steps are the monobromination of a beta-ketoester and chelation-controlled reduction of a bromomethyl ketone intermediate. Good overall yields, high diastereoselectivity, and excellent functional group compatibility are characteristic.