Martin Corless

A versatile route to substituted phosphinic acids

Abstract Mono-substituted phosphinic acids, symmetrical and unsymmetrical disubstituted phosphinic acids have been conveniently synthesized by 1,4 addition to α,β-unsaturated esters of bis(trimethylsilyl)phosphonite generated in situ, under very mild conditions.

An Imidazopiperidine Series of CCR5 Antagonists for the Treatment of HIV: The Discovery of N-{(1S)-1-(3-Fluorophenyl)-3-[(3-endo)-3-(5-isobutyryl-2-methyl-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridin-1-yl)-8-azabicyclo[3.2.1]oct-8-yl)propyl}acetamide (PF-232798)

Preventing entry of HIV into human host cells has emerged as an attractive approach to controlling viral replication. Maraviroc 1 is an approved antagonist of the human CCR5 receptor which prevents the entry of HIV. Herein, we report the design and discovery of a series of imidazopiperidine CCR5 antagonists which retain the attractive antiviral profile and window over hERG activity of maraviroc 1, combined with improved absorption profiles in rat and dog. Furthermore, this series of compounds has been shown to retain activity against a laboratory generated maraviroc-resistant HIV-1 strain, which indicates an alternative resistance profile to that of maraviroc 1. Compound 41f (PF-232798) was selected as a clinical candidate from the imidazopiperidine series and is currently in phase II clinical trials.

Asymmetric synthesis of β-amino acid derivatives by Michael addition to chiral 2-aminomethylacrylates

Abstract The addition of lithium enolates to chiral aminomethylacrylates 7 and 8 proceeded with excellent diastereodifferentiation (up to 98% de) and provided an expeditious synthesis of homochiral β-aminomethylglutarates 9 and 10 , on a scale of up to 500g. The acrylates 7 and 8 , and their antipodes, should be useful synthons for the synthesis of β-amino acid derivatives.

The discovery of UK-369003, a novel PDE5 inhibitor with the potential for oral bioavailability and dose-proportional pharmacokinetics

This paper describes our recent efforts to design and synthesise potent and selective PDE5 inhibitors and the use of in vitro predictors of clearance, absorption and permeability to maximise the potential for dose-proportional pharmacokinetics and good oral bioavailability in man. Optimisation of the preclinical profile resulted in the identification of UK-369003 (19a) and its nomination as a clinical candidate. The clinical pharmacokinetic and safety profile has enabled us to progress the compound to test its efficacy in patients with lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) and a paper describing its efficacy has recently been published.

The design and discovery of novel amide CCR5 antagonists.

The synthesis of a range of novel amine-containing structures and their primary potency as inhibitors of HIV-1 fusion via blocking of the CCR5 receptor is described. The development of the medicinal chemistry strategy and SARs which led to the identification of the piperidine amide compounds 33 and 36 as excellent leads for further evaluation is described, along with key physicochemical data which highlighted their lead potential.

The discovery of small molecule inhibitors of neutral endopeptidase. Structure-activity studies on functionalized glutaramides.

A series of small molecule glutaramides were synthesized and evaluated for potency against canine and human neutral endopeptidase using target criteria of molecular weight <400 and log P between 2 and 4.5 to maximize the likelihood of achieving good oral absorption. The structure‐activity relationship (SAR) investigations described in this paper led to the identification of an ethyl 1,3,4‐thiadiazole glutaramide which demonstrated good neutral endopeptidase potency, selectivity and excellent oral absorption in the rat.

2,4-Diaminopyridine δ-opioid receptor agonists and their associated hERG pharmacology

A number of libraries were produced to explore the potential of 2,4-diaminopyridine lead 1. The resulting diaminopyridines proved to be potent and selective delta-opioid receptor agonists. Several rounds of lead optimisation using library chemistry identified compound 17 which went on to show efficacy in an electromyography model of neuropathic pain. The structure-activity relationship of the series against the hERG ion channel proved to be a key selectivity hurdle for the series.

An in situ oxidation strategy towards overcoming hERG affinity

In an effort to overcome hERG affinity with a lead compound, several S-oxide and N-oxide analogues were synthesised with a much improved hERG profile but low in vivo absorption. This led to the implementation of an in situ oxidation strategy wherein a sulfide was dosed orally and systemic levels of the corresponding sulfoxide and sulfone were monitored. SAR and pharmacokinetic data to support this as a possible strategy are presented, although ultimately the approach was shown not to be suitable due to very low levels of active circulating metabolites.