Rhinovirus protease inhibitor

Scheme 1. Chemoenzymatic synthesis of a Rhinovirus protease inhibitor...

Martinez C, Yazbeck D, Tao J (2004) An efficient enzymatic preparation of rhinovirus protease inhibitor intermediates. Tetrahedron 60 759-764... 

For the enantiopure production of human rhinovirus protease inhibitors scientists from Pfizer developed a kinetic resolution and recycling sequence (Scheme 6.14 A). The undesired enantiomer of the ester is hydrolysed and can be racemised under mild conditions with DBU. This enzymatic kinetic resolution plus racemisation replaced a significantly more expensive chemical approach [52]. An enzymatic kinetic resolution, in combination with an efficient chemically catalysed racemisation, is the basis for a chiral building block for the synthesis of Talsaclidine and Revatropate, neuromodulators acting on cholinergic muscarinic receptors (Scheme 6.14B). In this case a protease was the key to success [53]. Recently a kinetic resolution based on a Burkholderia cepacia lipase-catalysed reaction leading to the fungicide Mefenoxam was described [54]. Immobilisation of the enzyme ensured >20 cycles of use without loss of activity (Scheme 6.14 C). 

R)-3-(4-fluorophenyl)-2-hydroxy propionic acid 1 is a building block for the synthesis of Rupintrivir, a rhinovirus protease inhibitor currently in human clinical trials to treat the common cold (Fig. 1) [1, 2], Retrosynthetically, Rupintrivir was prepared from four fragments the lactam derivative Pi, the chiral 2-hydroxy acid P2 (compound 1), the valine derivative P3, and an isoxazole acid chloride P4 (Fig. 1). In this chapter the preparation of 1 using a biocatalytic reduction performed in a membrane reactor will be discussed in detail. 

Martinez C, Yazbeck D, Tao J (2004) An efficient enzymatic preparation of rhinovirus protease inhibitor intermediates. Tetrahedron 60 759-764 Reetz MT, Wang LW, Bocola M (2006) Directed evolution of enantioselective enzymes iterative cycles of CASTing for probing protein-sequence space. Angew Chem Int Ed 45 1236-1241... 

Rhinovirus protease inhibitor enzymatic preparation of (A)-3-(4-fluorophenyl)-2-hydroxy propionic acid. 

The requirements of protease inhibitors as drugs in terms of potency, pharmacokinetics, and toxicity will vary depending on the nature of the infection and the goals of therapy. At one extreme is treatment of HlV-1, a chroific infection that requires life-long therapy and full suppression of viral replication. At the other extreme is the treatment of human rhinovirus (i.e., the cold virus), where short-term treatment to blunt viremia will likely be sufficient to reduce the unwanted symptoms of a cold. In all cases, viral proteases represent very attractive targets with familiar mechanisms of catalysis that frequently allow for the design of transition state analogs and with distinct specificities from host proteases. 

Dragovich PS, Webber SE, Babine RE et al (1998) Structure-based design, synthesis, and biological evaluation of irreversible human rhinovirus 3C protease inhibitors. J Med Chem 41 2819-2834... 

The bicyclic 2-pyridone-containing 3CP (human rhinovirus 3C protease) inhibitor 279 displayed improved inhibition properties and exhibited potent antirhinoviral activity in cell culture when tested against a number of different human rhinovirus (HRV) serotypes <2002BML733>. 

Dragovich, P. S., Zhou, R., Skalitzky, D. J., Fuhrman, S. A., Patick, A. K., Ford, . E., Meador, J. W., Ill, Worland, S. T. (1999) Solid-phase synthesis of irreversible human rhinovirus 3C protease inhibitors. Part 1 optimization of tripeptides incorporating N-terminal amides. Bioorg Med Chem 7, 589-598. 

Scheme 22. Synthesis of human rhinovirus 3C protease inhibitors.

Triterpene sulphates from the fungus Fusarium compactum inhibit rhinovirus 3C protease [58], synthetic cysteine protease inhibitors are... 

In order to design compounds able to react covalently with the nucleophilic cysteine of human 3C rhinovirus protease, scientists from Agouron designed vinylogous derivatives of the prototype inhibitor 3-carbamoyl-benzaldehyde (Figure 14.24). In this particular case, Michael acceptor reactivity is eventually the wanted feature. " ... 

LS. Zalman, M.A. Brothers, P.S. Dragovich, R. Zhou, T.J. Prins, S.T. Worland, A.K. Patick, Inhibition of human rhinovirus-induced cytokine production by AG7088, a human rhinovirus 3G protease inhibitor Antimicrob, Agents Chemother. 44 (2000) 1236-1241. 

E. L Brown,. W. Meador III, R.A. Ferre, I.E.V. Harr, M.B. Kosa, S.T. Worland, Structure-based design, synthesis, and biological evaluation of irreversible human rhinovirus 3C protease inhibitors. 4. incorporation of P, lactam moieties as l-glutamine replacements, I. Med. Chem. 42 (1999) 1213-1224. 

Rupintrivir (72, Scheme 2.11) is a peptidomimetic protease inhibitor developed by Agouron Pharmaceuticals (San Diego, CA) for the treatment of human rhinovirus (HRV). A key component of the rupintrivir pharmacophore is the a,(3-unsaturated ester moiety, which acts as a Michael acceptor, forming a covalent bond with cysteine residues in the active site of HRV 3C protease. Synthesis of the 7-amino a,(3-unsaturated ester portion of rupintrivir involved coupling L-glutamic acid derivative 66 with 4-benzyloxazolidinone 67 via a mixed anhydride. Formation of the corresponding sodium enolate, followed by alkylation with allyl iodide 69, gave the a-allyl amide 70. 

Rhinoviruses, which represent the single major cause of common cold, belong to the family of picornavimses that harbors many medically relevant pathogens. Inhibitors of the 3C protease, a cysteine protease, have shown good antiviral potential. Several classes of compounds were designed based on the known substrate specificity of the enzyme. Mechanism-based, irreversible Michael-acceptors were shown to be both potent inhibitors of the purified enzyme and to have antiviral activity in infected cells. 

Matthews DA, Dragovich PS, Webber SE, Fuhrman SA, Patick AK, Zalman LS, Hendrickson TF, Love RA, Prins TJ, Marakovits JT, Zhou R, Tikhe J, Ford CE, Meador JW, Ferre RA, Brown EL, Binford SL, Brothers MA, DeLisle DM, Worland ST (1999) Structure-assisted design of mechanism-based irreversible inhibitors of human rhinovirus 3C protease with potent antiviral activity against multiple rhinovirus serotypes. Proc Natl Acad Sci USA 96 11000-11007... 

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