title: 9-hydroxyazafluorenes and their use in thrombin inhibitors.
abstract: Optimization of a previously reported thrombin inhibitor, 9-hydroxy-9-fluorenylcarbonyl-l-prolyl-trans-4-aminocyclohexylmethylamide (1), by replacing the aminocyclohexyl P1 group provided a new lead structure, 9-hydroxy-9-fluorenylcarbonyl-l-prolyl-2-aminomethyl-5-chlorobenzylamide (2), with improved potency (K(i) = 0.49 nM for human thrombin, 2x APTT = 0.37 microM in human plasma) and pharmacokinetic properties (F = 39%, iv T(1/2) = 13 h in dogs). An effective strategy for reducing plasma protein binding of 2 and improving efficacy in an in vivo thrombosis model in rats was to replace the lipophilic fluorenyl group in P3 with an azafluorenyl group. Systematic investigation of all possible azafluorenyl P3 isomers and azafluorenyl-N-oxide analogues of 2 led to the identification of an optimal compound, 3-aza-9-hydroxyfluoren-9(R)-ylcarbonyl-l-prolyl-2-aminomethyl-5-chlorobenzylamide (19b), with high potency (K(i) = 0.40 nM, 2x APTT = 0.18 microM), excellent pharmacokinetic properties (F = 55%, T(1/2) = 14 h in dogs), and complete efficacy in the in vivo thrombosis model in rats (inhibition of FeCl(3)-induced vessel occlusions in six of six rats receiving an intravenous infusion of 10 microg/kg/min of 19b). The stereochemistry of the azafluorenyl group in 19b was determined by X-ray crystallographic analysis of its N-oxide derivative (23b) bound in the active site of human thrombin.
authors.affiliation: Department of Medicinal Chemistry, Biological Chemistry, Pharmacology, Drug Metabolism, and Molecular Systems, Merck Research Laboratories, West Point, Pennsylvania 19486, USA. ken_stauffer@merck.com
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Stauffer
authors.forename: Peter D
authors.initials: PD
authors.lastname: Williams
authors.forename: Harold G
authors.initials: HG
authors.lastname: Selnick
authors.forename: Philippe G
authors.initials: PG
authors.lastname: Nantermet
authors.forename: Christina L
authors.initials: CL
authors.lastname: Newton
authors.forename: Carl F
authors.initials: CF
authors.lastname: Homnick
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Zrada
authors.forename: S Dale
authors.initials: SD
authors.lastname: Lewis
authors.forename: Bobby J
authors.initials: BJ
authors.lastname: Lucas
authors.forename: Julie A
authors.initials: JA
authors.lastname: Krueger
authors.forename: Beth L
authors.initials: BL
authors.lastname: Pietrak
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Lyle
authors.forename: Rominder
authors.initials: R
authors.lastname: Singh
authors.forename: Cynthia
authors.initials: C
authors.lastname: Miller-Stein
authors.forename: Rebecca B
authors.initials: RB
authors.lastname: White
authors.forename: Bradley
authors.initials: B
authors.lastname: Wong
authors.forename: Audrey A
authors.initials: AA
authors.lastname: Wallace
authors.forename: Gary R
authors.initials: GR
authors.lastname: Sitko
authors.forename: Jacquelyn J
authors.initials: JJ
authors.lastname: Cook
authors.forename: Marie A
authors.initials: MA
authors.lastname: Holahan
authors.forename: Maria
authors.initials: M
authors.lastname: Stranieri-Michener
authors.forename: Yvonne M
authors.initials: YM
authors.lastname: Leonard
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Lynch
authors.forename: Daniel R
authors.initials: DR
authors.lastname: McMasters
authors.forename: Youwei
authors.initials: Y
authors.lastname: Yan
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D001798:Blood Proteins / Q000378:metabolism; D018360:Crystallography, X-Ray; D004285:Dogs; D005449:Fluorenes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006207:Half-Life; D006801:Humans; D066298:In Vitro Techniques; D008253:Macaca mulatta; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D008958:Models, Molecular; D011392:Proline / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013917:Thrombin / Q000037:antagonists & inhibitors*
chemical_list: C500158:3-aza-9-hydroxyfluoren-9-ylcarbonyl-prolyl-2-aminomethyl-5-chlorobenzylamide; D001798:Blood Proteins; D005449:Fluorenes; D011392:Proline; D013917:Thrombin