Synthesis of unprotected and borane-protected cyclic phosphines using Ru- and Mo- based olefin metathesis catalysts.

Ru- and Mo-based catalysts can be used in ring closing metathesis (RCM) reactions to synthesise cyclic phosphines protected as their borane complexes. The compatibility of the Schrock Mo-catalyst and the N-heterocyclic carbene Ru-catalysts with this class of substrates is particularly noteworthy as asymmetric RCM (ARCM) is now emerging as a new tool for the preparation of homochiral phosphines. One of the key results is that the Mo-catalyst allows the ring closure of the unprotected diallylphenylphosphine with 95% conversion.

Pyrrolidine-5,5-trans-lactams. 5. Pharmacokinetic optimization of inhibitors of hepatitis C virus NS3/4A protease.

[reaction: see text] In this, the second of two Letters, the optimization of the pyrrolidine-5,5-trans-lactam template (exemplified by 1a) as a mechanism-based inhibitor of hepatitis C NS3/4A protease is described. "Right Box" analysis of cassette dosing screening pharmacokinetic data was used to rapidly categorize the compounds. GW0014 (compound 4d) emerged as the compound displaying an optimal balance of biochemical and replicon potency, along with low i.v. clearance in the dog.

The design of potent, non-peptidic inhibitors of hepatitis C protease.

The pyrrolidine-5,5-trans-lactam template was used to design small, neutral, mechanism-based inhibitors of hepatitis C NS3/4A protease displaying potent activity in the replicon cell-based assay. The activity of this series is not dependent upon its chemical reactivity and molecules have been synthesised which combine enhanced biochemical potency with improved plasma stability. Promising initial pharmacokinetic data indicating the potential for further optimisation of this series into low molecular weight, drug-like inhibitors is presented.

Design and synthesis of spiro-cyclopentenyl and spiro-[1,3]-dithiolanyl substituted pyrrolidine-5,5-trans-lactams as inhibitors of hepatitis C virus NS3/4A protease.

Using the pyrrolidine-5,5-trans-lactam template, we have designed small, neutral, mechanism-based inhibitors of hepatitis C NS3/4A protease. Compound 2b, with a spiro-cyclobutyl P1 substituent and an isopropyl carbonyl substituent at the lactam nitrogen, has an IC(50) value in the replicon cell-based assay of 3 microM.

Pyrrolidine-5,5-trans-lactams. 1. Synthesis and incorporation into inhibitors of hepatitis C virus NS3/4A protease.

[reaction: see text] In this, the first of two letters, we outline the use of the pyrrolidine-5,5-trans-lactam template to design small, neutral, mechanism-based inhibitors of hepatitis C NS3/4A protease. The hitherto unreported reaction of the acyl iminium ion precursor 4 with dialkyl-substituted silyl ketene acetals (e.g., 8b) is described. Compound 12b, with a spirocyclobutyl P1 substituent and a cyclopropylacyl substituent on the lactam nitrogen, has a k(obs)/I of 400 M(-)(1) s(-)(1) and demonstrates activity in a replicon cell-based surrogate HCV assay.

Pyrrolidine-5,5-trans-lactams. 2. The use of X-ray crystal structure data in the optimization of P3 and P4 substituents.

[reaction: see text] In this, the second of two letters, we describe the elaboration of the pyrrolidine-5,5-trans-lactam template to delineate the requirements for optimal substitution of the pyrrolidine and lactam nitrogen atoms. Central to the strategy is the use of rapid iterative synthesis in conjunction with X-ray crystal structure determination of ligand-protein complexes.