A series of α-alkyl-α-amino-β-sulphone hydroxamates was prepared and evaluated for potency versus MMP-2 and MMP-13, and for selectivity versus MMP-1. Low nanomolar potency was obtained with selectivity versus MMP-1 ranging from \u3e10 to \u3e1000. Selected compounds were orally bioavailable

Becker, Daniel

DeCrescenzo, Gary A.

Freskos, John

Getman, Daniel P.

Name not available

Alpha-Alkyl-alpha-amino-beta-sulphone Hydroxamates as Potent MMP Inhibitors that Spare MMP-1

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Loyola University ChicagoLoyola eCommonsChemistry: Faculty Publications and Other Works Faculty Publications10-22-2001Alpha-Alkyl-alpha-amino-beta-sulphoneHydroxamates as Potent MMP Inhibitors thatSpare MMP-1Daniel BeckerLoyola University Chicago, dbecke3@luc.eduGary A. DeCrescenzoJohn FreskosDaniel P. GetmanAuthor ManuscriptThis is a pre-publication author manuscript of the final, published article.This Article is brought to you for free and open access by the Faculty Publications at Loyola eCommons. It has been accepted for inclusion inChemistry: Faculty Publications and Other Works by an authorized administrator of Loyola eCommons. For more information, please contactecommons@luc.edu.This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.© 2001 ElsevierRecommended CitationBecker, Daniel; DeCrescenzo, Gary A.; Freskos, John; and Getman, Daniel P.. Alpha-Alkyl-alpha-amino-beta-sulphone Hydroxamatesas Potent MMP Inhibitors that Spare MMP-1. Bioorganic & Medicinal Chemistry Letters, 11, 20: , 2001. Retrieved from LoyolaeCommons, Chemistry: Faculty Publications and Other Works, http://dx.doi.org/10.1016/S0960-894X(01)00557-1  α-Alkyl-α-Amino-β-Sulphone Hydroxamates as  Potent MMP Inhibitors Which Spare MMP-1  Daniel P. Becker*a, Gary DeCrescenzo,b John Freskos, b Daniel P. Getman,b Susan L. Hockerman,a Madeleine Li,a Pramod Mehta,b Grace Munieb, Craig Swearingenb  Departments of Medicinal Chemistry and Inflammation-Oncology Pharmacia Research & Development a4901 Searle Parkway, Skokie, IL 60077  b700 Chesterfield Village Parkway, St. Louis, MO  63198  Abstract:  A series of α-alkyl-α-amino-β-sulphone hydroxamates was prepared and evaluated for potency versus MMP-2 and MMP-13, and for selectivity versus MMP-1. Low nanomolar potency was obtained with selectivity versus MMP-1 ranging from >10 to >1,000.  Selected compounds were orally bioavailable.  Introduction In our previous letter we descirbed a series of α-amino-β-sulphone hydroxamates which are potent inhibitors of MMP-13 which spare MMP-1.1  Overexpressed MMPs play a crucial role in tumor growth and metastasis in cancer, and in the destruction of articular cartilage in osteoarthritis (OA) and rheumatoid arthritis (RA).  Hence, the inhibition of the relevant MMP enzymes may prove to be clinically effective in halting the advance of these diseases.2  The gelatinases A and B (MMP-2 and MMP-9) have been implicated in tumor progression,3  and MMP-13 has been implicated in the destruction of articular cartilage in arthritis.4  Herein we report the preparation and preliminary SAR of a series of α-amino-α-alkyl-β-sulphones which are highly selective in sparing MMP-1, based on the hypothesis that the musculoskeletal side effect observed clinically with the broad-spectrum inhibitor marimastat5 is due to potent inhibition of MMP-1. Alkyl substituents alpha to the hydroxamate were employed to modulate pharmacokinetic properties including absorption and half-life, as well as physicochemical properties, while the P1' substituent was varied to optimize potency and selectivity. Chemistry The targeted α-methyl-α-amino diphenyl ether hydroxamates of type 5 were prepared starting with a halide displacement of chloroacetone (1) with 4-phenoxythiophenol6 to afford 2 (Scheme 1).   Strecker synthesis then gave the nitrile 3 which was hydrolyzed to the carboxylic acid.  Oxidation of the sulfide after protection of the amino group as the acetamide, and subsequent deprotection then gave the amino acid 4.  Functionalization of the amino group was accomplished by alkylation, acylation or reductive amination as required, and standard EDC coupling with hydroxylamine afforded the diphenyl ether sulphone hydroxamates 5.    Scheme 1 OH3C ClOH3C SRNH2NCSRH3C1) HClNH2HO2C SOPhH3C2) AcCl, Et3N3) Oxone®4) HCl, HOAcO O1) R2 functionalization2) HONH2, EDCHOBT, DMF NHSOPhH3CO OONHHOR2Et3N, MeOH1 2 34 5HS RNaCN,NH4Cl, NH4OHNH3, MeOH(R = OPh) The diaryl thioether 7 was prepared by reacting chloroacetone (1) with 4-fluorothiophenol (R = F).  Strecker synthesis gave nitrile 3 (R = F) which was hydrolyzed and protected as the acetamide (Scheme 2).  Oxidation then afforded the corresponding 4-fluorophenylsulphone, and nucleophilic aromatic substitution with thiophenol gave carboxylic acid 6.  Acetamide hydrolysis preceded amino functionalization with the appropriate R2 reagent, and EDC coupling afforded the hydroxamates 7.   Scheme 2 1) HClNHHO2C SSPhH3C2) AcCl, Et3N3) Oxone®1) HCl, HOAcO O2) R2 functionalization3) HONH2, EDCHOBT, DMF NHSSPhH3CO OONHHOR26 7Ac4) thiophenolCs2CO33(R = F) As illustrated in Scheme 3, α-pyrrolidine-β-sulphones were prepared from racemic methyl N-Cbz-proline (8).  Alkylation7 with methylene diiodide gave the α-iodomethyl derivative which was used to alkylate 4-phenoxythiophenol, and oxidation gave the sulphone 9.  The Cbz protecting group was removed by hydrogenolysis, exposing the amine which was functionalized by alkylation with propargyl bromide.  Saponification of the methyl ester and coupling with hydroxylamine then afforded the hydroxamate 10 (R2 = propargyl).   Scheme 3 8 9 10NCO2MeCbz1) LDA, CH2I2thiophenol2) 4-phenoxy-NMeO2CCbz3) Oxone®SOPhO O1) Pt/C, H22) R2 functionalization3) NaOH4) HONH2, EDCNR2SOPhO OONHHO The α-phenyl-α-amino derivative 15 (Scheme 4) was prepared from D,L-phenylglycine (11) by benzoylation and treatment with acetic anhydride to give the 2-phenyloxazolone 128 (Scheme 4).  Alkylation of this azlactone with methylene diiodide gave iodomethyl azlactone 13, and displacement of the iodide with 4-phenoxythiophenol and subsequent oxidation with metachloroperbenzoic acid gave the sulphone 14.  The oxazolone was then hydrolyzed and the resulting carboxylic acid coupled with TMS-protected hydroxylamine to afford 15 (R2 = H).  Alternatively, the oxazolone ring was opened directly with hydroxylamine to afford the benzamide hydroxamate (R2 = Bz). Scheme 4 NHSOPhO OONHHOR2OHONH2Ph2) Ac2OONPhOPhCH2I2i-Pr2NEtONOPhPh I1) 4-phenoxy-ONOPhPh S2) MCPBAOPh2) H2NOTMS11 12 1314 15thiophenol, NaH1) BzCl1) HCl, HOAcEDC, HOBTO O  Results and Discussion Table 1 summarizes the potency versus MMP-2, MMP-13 and MMP-1 for compounds of generic structures 5, 7 and 15.  The diaryl ethers (X = O) were an order of magnitude more potent than the corresponding thioethers (X = S), although the thioethers were noted to be somewhat more selective in sparing MMP-1 (5a and 5b versus 7a and 7b).  Amides of the α-amino group (compounds 5a, 5j, 7a and 15a) were not well tolerated, whereas simple alkyl and aralkyl amines were potent for both MMP-2 and MMP-13.  Disubstitution on the amine led to a loss of potency (5c).  The α-phenyl amine 15b was potent for MMP-13 and MMP-2, but was also somewhat more potent for MMP-1.  Almost all compounds exhibited excellent selectivity versus MMP-1, in several cases exceeding 1000X for the ratio of IC50 values (MMP-1/MMP-2 and MMP-1/MMP-13), in contrast to the broad-spectrum inhibitors CGS 27023A and marimastat.  Table 2 shows the enzyme potency of proline-derived analog 10.  Since the racemate 10 was found to be quite potent, the material was resolved into its enantiomers via chiral chromatography.9  The first eluter, hydroxamate 10a, was found to be the more potent enantiomer (eutomer) by at least two orders of magnitude against both MMP-13 and MMP-2 as compared to the less potent enantiomer (distomer) 10b.  Compound 10a was also highly selective in sparing MMP-1 (3000X).      Table 1: IC50 (nM)10 values for α-alkyl-α-amino-β-sulphone hydroxamates NSR2O OXPhNHOHOR1R3 Compound R1 R2 R3 X MMP-13 MMP-2 MMP-1 5a CH3 Ac H O 41.5 40.0 >10,000 5b CH3 H H O 0.2 0.6 170 5c CH3 CH3 CH3 O 24.0 5.0 >10,000 5d CH3 CH2CH3 H O 1.6 1.3 1600 5e CH3 CH2Ph H O 0.3 0.2 1200 5f CH3 CH2CH2Ph H O 2.4 1.3 2400 5g CH3 3,4-methylenedioxybenzyl H O 1.1 0.5 2350 5h CH3 2-naphthylmethyl H O 1.4 0.4 >10,000 5i CH3 propargyl H O 0.6 0.2 700 5j CH3 pyrrolidineacetyl H O 160 80 >10,000 7a CH3 Ac H S 580 540 >10,000 7b CH3 H H S 2.4 3.2 4400 15a Ph benzoyl H O 161 184 >10,000 15b Ph H H O 0.4 0.2 130 CGS 27023A     5.1 4.6 34.3 marimastat     2.0 0.75 2.9  Table 2: IC50 (nM)10 values for α-pyrrolidine-β-sulphone hydroxamates SO OOPhNHOHON R2 Compound R2 MMP-13 MMP-2 MMP-1 10 (racemic) propargyl 1.3 0.2 400 10a (eutomer) propargyl <0.1 <0.1 300 10b (distomer) propargyl 60.0 19.3 >10,000  Selected analogs were dosed orally in rats at 20 mpk to assess absorption by measuring Cmax, and the concentration remaining at 6 hours was used as an initial rough indicator of the half-life.  The α-methyl-α-amino analog 5b showed a high Cmax of 6.43 ug/ml, somewhat greater than the corresponding thioether 7b (Cmax = 1.54 ug/ml).  N-ethyl and N-benzyl analogs 5d and 5e were moderately well absorbed (Cmax = 0.561 and 0.216 ug/ml, respectively), and N-propargyl amine 5i exhibited a Cmax of 1.37 ug/ml.  However, all of the compounds tested were less than 15 ug/ml in plasma at the 6 h time point. In summary, we have described a promising series of α-alkyl-α-amino-β-sulphone hydroxamates which are potent inhibitors of both MMP-2 and MMP-13, and which spare MMP-1.  Several analogs showed good absorption when administered orally in the rat.  The efficacy of these compounds in animal models of cancer and arthritis will be disclosed in due course.  References and Notes 1.  Becker, D. P.; Barta, T. E.; Bedell, L.; DeCrescenzo, G.; Freskos, J.; Getman, D. P.; Hockerman, S. L.; Li, M.; Mehta, P.; Mischke, B.; Munie, G.; Swearingen, C.; Villamil, C. I. Bioorg. Med. Chem. Lett. 2001, ##, ###. 2.  Cawston, T. E. Pharmacol. Ther. 1996, 70, 163.   3.  Nelson, A. R.; Gingleton, B.; Rothenberg, M. L.; Matrisian, L. M. J. Clinical Oncology, 2000, 18, 1135. 4.  Freemont, A. J.; Byers, R. J.; Taiwo, Y. O.; Hoyland, J. A. Ann. Rheum. Dis. 1999, 58, 357. 5.  Wojtowicz-Praga, S.; Torri, J.; Johnson, M.; Steen, V.; Marshall, J.; Ness, E.; Dickson, R.; Sale, M.; Rasmussen, H. S.; Chiodo, R. A.; Hawkins, M. J. Clin. Oncol. 1998, 16, 2150. 6.  Freskos, J. N.; Mischke, B. V.; DeCrescenzo, G. A.; Heintz, R.; Getman, D. P.; Howard, S. C.; Kishore, N. N.; McDonald, J. J.; Munie, G. E.; Rangwala, S.; Swearingen, C. A.; Voliva, C.; Welsch, D. J. Bioorg. & Med. Chem. Lett. 1999, 9, 943. 7.  Chan, C. O.; Cooksey, C. J.; Crich, D.  J. Chem. Soc., Perkin Trans. 1  1992,  7,  777. 8.  Obrecht, D.; Spiegler, C.; Schoenholzer, P.; Mueller, K.; Heimgartner, H.; Stierli, F. Helv. Chim. Acta  1992,  75,  1666. 9.  The resolution of 30 was accomplished using a Chiralpak AD column (4.6 mm X 25 cm) at a flow rate of 1.0 ml/min eluting with a mobile phase of 35/65 ethanol/heptane with 0.2% trifluoroacetic acid.  Tony Yan is gratefully acknowledged for performing the chiral separation. 10. Inhibitors were assayed against purified hMMP-13, hMMP-1 and hMMP-2 using an enzyme assay based on cleavage of the fluorogenic peptide MCA-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2.  This is similar to conditions described by C. G. Knight et. al. in FEBS Lett. 1992, 296, 263, except that 0.02% final concentration of 2-mercaptoethanol was used in the MMP-13 and MMP-1 assays.  All basic compounds were tested as their hydrochloride salts except for 10a and 10b, which were tested as the trifluoroacetate salts. 

Alpha-Alkyl-alpha-amino-beta-sulphone Hydroxamates as Potent MMP Inhibitors that Spare MMP-1

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