Synthesis of analogs of forodesine HCl, a human purine nucleoside phosphorylase inhibitor-Part I.

Forodesine HCl is being investigated as a potential therapeutic target for the control of T-cell proliferation. During our ongoing process development work on forodesine HCl several novel compounds were identified as possible impurities in the process. Herein we present the synthesis of three novel compounds (2-4).

Synthesis of labeled BCX-4208, a potent inhibitor of purine nucleoside phosphorylase.

BCX-4208, a novel inhibitor of the enzyme purine nucleoside phosphorylase, mimics the charged ribosyl oxocarbenium ion formed during the transition state of the enzyme-catalyzed C-N bond cleavage of nucleosides. A slow-onset, tight-binding inhibitor with a Ki(*) of 16 +/- 1.4 pM, BCX-4208 is one of the most potent inhibitors known for the enzyme. In support of our BCX-4208 clinical program, a mass spectrometric assay has been developed that required labeled BCX-4208 as an internal standard. The synthesis of [(2)H](2)-BCX-4208 and [(13)C]-BCX-4208 is described in this report.

Synthesis of a potent 5'-methylthioadenosine/S-adenosylhomocysteine (MTAN) inhibitor.

MTAN has been known to occur in a variety of bacterial cell types. Due to the evolution of bacterial strains which are resistant to some of the most powerful antibiotics there has been a renewed interest in the development of novel anti-microbial agents. Presented herein is a synthesis of a potent MTAN inhibitor, namely 2-amino-4-[5-(4-amino-5H-pyrrolo[3,2-d]pyrimidin-7-yl)-3,4-dihydroxypyrrolidin-2-ylmethylsulfanyl]-butyric acid (1).

Synthesis and inhibitory activity of benzoic acid and pyridine derivatives on influenza neuraminidase.

Based upon the activity and X-ray crystallographic studies of tri-substituted benzene derivatives containing carboxylic acid, acetamido and guanidine groups, we investigated the effect of the fourth substituent to fulfill the fourth pocket of neuraminidase enzyme. The groups selected as fourth substituents were hydroxymethyl, hydroxyethyl, oxime and amino. These tetra-substituted benzene derivatives were synthesized and evaluated for neuraminidase inhibitory activity. All these compounds were found to have poorer IC(50) values than the tri-substituted compounds. Further, benzene ring was replaced by pyridine ring and di, tri and tetra-substituted pyridine derivatives were synthesized. The activity of the pyridine derivatives was comparable to benzene derivatives. The fourth substituent seems to disturb the binding of the other three substituents, so the activity is reduced as compared to tri-substituted benzene and pyridine derivatives.

Synthesis and pharmacokinetic and pharmacodynamic evaluation of the forodesine HCl analog BCX-3040.

Forodesine HCl is a potent inhibitor of the enzyme purine nucleoside phosphorylase (PNP) and is currently in clinical trials for the treatment of leukemia and lymphoma. Animal models indicated that forodesine HCl would have low oral bioavailability in humans and it was initially developed as an intravenous formulation. We were interested in identifying analogs of forodesine HCl with improved oral bioavailability. The 2'-deoxy analog (BCX-3040) was synthesized and its pharmacokinetic and pharmacodynamic properties compared with forodesine HCl.

A novel series of potent and selective small molecule inhibitors of the complement component C1s.

Activation of the classical pathway of complement has been implicated in disease states such as hereditary angioedema, ischemia-reperfusion injury and acute transplant rejection. The trypsin-like serine protease C1s represents a pivotal upstream point of control in the classical pathway of complement activation and is therefore likely to be a useful target in the therapeutic intervention of these disease states. A series of thiopheneamidine-based inhibitors of C1s has been optimized to give a 70 nM inhibitor that inhibits the classical pathway of complement activation in vitro.

Synthesis of a potent transition-state inhibitor of 5'-deoxy-5'-methylthioadenosine phosphorylase.

Human 5'-deoxy-5'-methylthioadenosine phosphorylase (MTAP) participates in the purine salvage pathway to generate adenine and methylthioribose-1-phosphate, which in turn is converted into adenine nucleotides and methionine. Hence, inhibition of MTA phosphorylase may be an effective target in the design of potential antiproliferative agents. Presented herein is the synthesis of 2-(4-amino-5H-pyrrolo[3,2-d]pyrimidin-7-yl)-5-methylsulfanylmethylpyrrolidin-3,4-diol (1), a potent inhibitor of MTAP.

Intravenous and oral pharmacokinetic study of BCX-1777, a novel purine nucleoside phosphorylase transition-state inhibitor. In vivo effects on blood 2'-deoxyguanosine in primates.

Administration of BCX-1777 to primates results in a rapid elevation of plasma 2'-deoxyguanosine (up to 0.4 microg/ml, 1.5 microM). Maximum 2'-deoxyguanosine C(max), 0.4 microg/ml, was achieved with the lowest IV dose of BCX-1777 and increasing the IV dose of BCX-1777 did not increase the 2'-deoxyguanosine C(max). However, plasma 2'-deoxyguanosine remained elevated longer as the dose of BCX-1777 increased. In contrast, increases in the oral dose of BCX-1777 did increase the plasma C(max) of 2'-deoxyguanosine. This was in spite of the observation that overall oral bioavailability of BCX-1777 was only 8.2%. This suggests that the BCX-1777 was absorbed slowly producing a sustained low concentration of BCX-1777, resulting in prolonged plasma concentrations of 2'-deoxyguanosine. After IV dosing, the BCX-1777 was cleared relatively quickly and the plasma 2'-deoxyguanosine tracked slightly behind the BCX-1777. IV administration of 5 mg/kg of BCX-1777 twice daily maintains the plasma 2'-deoxyguanosine concentrations at around 0.3 microg/ml (1.1 microM). These data indicate that oral and IV administration of BCX-1777 induce a rapid rise in 2'-deoxyguanosine and that oral dosing at 8.8 and 17.6 mg/kg are at least equivalent to 4.4 mg/kg IV in effecting the accumulation of 2'-deoxyguanosine. Finally, 2'-deoxyguanosine plasma concentration was maintained longer in the three highest oral doses in comparison to all IV doses.

An Improved Synthesis of 7-Substituted Pyrrolo[3,2-d]pyrimidines.

Base (NaOMe)-catalyzed condensation of 3,3-dimethoxypropionitrile with aldehydes followed by hydrolysis with 6 N HCl gives the unsaturated cyano aldehydes 5. Catalytic reduction of the double bond followed by reaction with diethyl aminomalonate affords the enamines 7, which cyclize to the aminopyrroles 2 on treatment with NaOMe. While the amino group in 2 is unreactive toward many guanylating reagents, acid (AcOH)-catalyzed guanylation occurs easily with 10 to give 12 along with methyl mercaptan as a byproduct. Subsequent facile removal of the carbamate groups and ring closure to the pyrrolo[3,2-d]pyrimidine ring system occurs on treatment with base. The use of HgCl(2) in place of AcOH ties up the mercaptan and eliminates the odor problem. For larger scale reactions where the mercaptan odor and the use of Hg salts are undesirable, the use of the methoxy analogue 11 is preferred. Using this procedure, benzaldehyde has been converted to the 7-(phenylmethyl)pyrrolo[3,2-d]pyrimidine (1a), a potent inhibitor of the enzyme purine nucleoside phosphorylase, in 31% overall yield with only three isolation steps.