Thiophene as a structural element of physiologically active substances. 20. Thiophene analogs of the leukotriene D4 antagonist Ro 23-3544]

The synthesis of 6-Acetyl-7-[[5-(5-acetyl-4-hydroxy-3-propyl-2-thienyl- oxy)pentyl]oxy]-3,4-dihydro-2H-1-benzopyran-2-carboxylic acid (1), a thiophene analogue of the leukotriene antagonist Ro 23-3544, is described. Compound 1 shows almost no effect on leukotriene D4 induced broncho-constriction on anesthesized guinea pigs.     

3-Methyl-2H-1-benzopyran potassium channel activators

By aldol condensation of 4-chromanones with paraformaldehyde, 3-alkylenechromanones 10 were obtained which gave 3-alkylchromenes following reduction and dehydration. Subsequent 3-chloroperbenzoic acid oxidation produced the versatile epoxide intermediates 15, from which 3,4-epoxy-3,4-dihydro-2,2,3-trimethyl-2H-1-benzopyran-6-carbonitrile (15a) was resolved into its enantiomers by entrainment. In addition to the methyl group, the benzyl, alkyloxymethyl, and 2-nitroethyl residues could be introduced in the 3-position. Treatment of 15a with 2-pyridone simultaneously gave N- and O-substituted products 19a and 20. 19a easily gave 4-(1,2-dihydro-2-oxo-1-pyridyl)chromene 21 by treatment with base. The corresponding pyrrolidinone compounds 26 and 27 were obtained by a slightly modified procedure. Reaction with 2,4-dihydroxypyridine or 3,6-pyridazinediol resulted in the exclusive formation of 4-(heterocyclyloxy)chromanols (31 and 32). Treatment of 15a with 3-amino-6-pyridazinol gave 4-(3-amino-1,6-dihydro-6-oxo-1-pyridazinyl)chromanol derivative 34 lacking an NH bridge. This could be established after methylation of the ring-nitrogen atom (----35). Trans-configurated 3-methyl-4-pyridone compound 36 was obtained by addition of methyllithium to chromene 3. Hyperpolarizing and antispasmodic or relaxing effects of the compounds were determined in organ bath studies using pig coronary arteries precontracted with acetylcholine or rabbit main pulmonary arteries precontracted with noradrenaline. In the 3-methyl series the classical pyridone and pyrrolidinone structures (9, 21, 26, 27) were only weakly active or inactive, but the corresponding 4-(heterocyclyloxy) and 4-(heterocyclylamino) derivatives (31, 32, 35) were even more potent than the demethyl analogues. In conformation/activity investigations it was found that the activity of the 4-substituted benzopyran derivatives seems to be dependent on the relative orientation of their ring systems.     

盐酸奈必洛尔的合成

6-氟-3，4-二氢-2H-1-苯并吡喃-2-甲醛与亚硫酸氢钠和氰化钠反应制得2-羟基-2-（6-氟-3，4-二氢-2H-1-苯并吡喃-2-基）乙腈，经硅胶柱色普分离，得到未见文献报道的顺式（3A）和反式（3B）非对映异构体。分别合成顺式，2-羟基-2-（6-氟-3，4-二氧-2H-1-苯并吡喃-2-基）乙醛（S）和反式-N-[2-羟基-2-（6-氟-3，4-二氢-2H-1-苯并吡喃-2-基）乙基]苄胺（8）。5和8经催化氢化及缩合、还原脱苄基、成盐后重结晶等步骤得到抗高血压药盐酸奈必洛尔。     

Synthesis,anticonvulsant and neurotoxicity evaluation of some new pyrimidine-5-carbonitrile derivatives

A series of 2-[2-(substituted benzylidene) hydrazinyl]-4-(4-methoxyphenyl)-6-oxo-1,6-dihydro-pyrimidine-5-carbonitrile (3–16) were synthesized by refluxing 2-hydrazino-4-(4-methoxy-phenyl)-6-oxo-1,6-dihydro-pyrimidine-5-carbonitrile (2) with different substituted aromatic aldehydes in glacial acetic acid and absolute alcohol mixture (8:2). The compounds were evaluated for their anticonvulsant and neurotoxicity effect. In MES test compounds 2-[2-(4-bromo-benzylidene)-hydrazinyl]-4-(4-methoxyphenyl)-6-oxo-1,6-dihydro-pyrimidine-5-carbonitrile (5), 2-[2-(4-hydroxy-benzylidene)-hydrazinyl]-4-(4-methoxyphenyl)-6-oxo-1,6-dihydro-pyrimidine-5-carbonitrile (9), and 2-[2-(3-fluoro-benzylidene)-hydrazinyl]-4-(4-methoxyphenyl)-6-oxo-1,6-dihydro-pyrimidine-5-carbonitrile (16) were found to be highly active at a dose level of 30 mgkg⁻¹ at 0.5 h time interval, indicating their ability to prevent seizure spread at a relatively low dose.     

Synthesis and calcium antagonistic activities of fecal metabolites of a new calcium antagonist (+)-(R)-3,4-dihydro-2-[5-methoxy-2-[3-[N-methyl-N- [2-[(3,4-methylenedioxy)phenoxy]ethyl]amino]propoxy]phenyl]-4- methyl-3-oxo-2H-1,4-benzothiazine (SD-3211) in rats

In order to confirm the structure of three fecal metabolites, M-I, M-II and M-III, of a new calcium antagonist, (+)-3,4-dihydro-2-[5-methoxy-2-[3-[N-methyl-N-[2-[(3,4-methylenedioxy) phenoxy]ethyl]amino]propoxy]phenyl]-4-methyl-3-oxo-2H-1,4- benzothiazine (SD-3211), in rats, (+)-3,4-dihydro-2-[5-hydroxy-2-[3-[N-methyl-N-[2- [(3,4-methylenedioxy)-phenoxy]ethyl]amino]propoxy]phenyl]-4-methyl- 3-oxo-2H-1,4-benzothiazine((+)-I), (+)-3,4-dihydro-2-[5-hydroxy-2-[3-[N- [2-[(3,4-methylenedioxy) phenoxy]ethyl]amino] propoxy]-phenyl]-4-methyl-3-oxo-2H-1,4-benzothiazine((+)-II) and (+)-3,4-dihydro-2-[5-methoxy-2-[3-[N-[2-[(3,4-methylenedioxy) phenoxy]ethyl]amino]propoxy]phenyl]-4-methyl-3-oxo-2H-1,4- benzothiazine((+)-III) were synthesized. Compounds (+)-I, (+)-II and (+)-III were identified with the fecal metabolites M-I, M-II and M-III, respectively. The calcium antagonistic activities of (+)-I, (+)-II and (+)-III were examined.     

Synthesis and biological studies of triazolo-/thiadiazolo-benzoxazines

Diethyl bromomalonate (2) with an equimolar amount of 2-aminophenol (1) in the presence of sodium fluoride undergoes a cyclization reaction to form 2H,4H-2-ethoxycarbonyl-3,4-dihydro-3-oxo-1,4-benzoxazine (3). Furthermore, compound 3 undergoes a condensation reaction with hydrazine hydrate in the presence of methanol to yield 2H,4H-2-hydrazinocarbonyl-3,4-dihydro-3-oxo-1,4-benzoxazine (4), which on further reaction with aryl isothiocyanates gave 2H,4H-2-[ (4'-substituted)-phenylthiosemicarbazino]-carbonyl-3,4-dihydro-3-oxo-1,4-benzoxazine (5). Compound 5 on treatment with NaOH, cone. H2SO4 and diethylmalonate (6). afforded 2H,4H-2-[2'H-3'-thioxo-4'-substituted phenyl-1',2',4'-triazole-5-yl]- 3,4-dihydro-3-oxo-1,4benzoxazine (7). 2H,4H-2-[2'-amino-(substituted)-phenyl-1,3',4'-thiadiazol-5-yl]-3,4-dihydro-3-oxo-1,4-benzoxazine (8) and 2H,4H-2-[5'H-5'-dihydro-2'-thioxo-3'-phenyl-4',6'-dioxo-1,3-diazine]-aminocarbonyl-3,4-dihydro-3-oxo-1,4-benzoxazine (9), respectively. The synthesized compounds were investigated for their antibacterial activities against Gram positive as well as Gram negative bacteria with ampicillin trihydrate as standard drug. Structures have been elucidated on the basis of spectral and chemical analyses.     

Bioactive coumarin derivatives from the fern Cyclosorus interruptus

Three new coumarin derivatives, compounds 1-3, three new furanocoumarins, compounds 4-6, and a novel dioxocane derivative, compound 7, were isolated from the fern Cyclosorus interruptus (Willd.) H. It?. Based on spectrometric and spectroscopic analysis (FAB or El mass spectrometry as well as 1D and 2D NMR experiments) their structures were characterised as 5,7-dihydroxy-6-methyl-4-phenyl-8-(3-phenylpropionyl)-1-benzopyran-2-one (1), 5,7-dihydroxy-6-methyl-4-phenyl-8-(3-phenyl-trans-acryloyl)-1- benzopyran-2-one (2), 5,7-dihydroxy-8-(2-hydroxy-3-phenylpropionyl)-6-methyl-4-phenyl-1- benzopyran-2-one (3), 8-benzyl-5,8-dihydroxy-6-methyl-4-phenylfuro[2,3-h]-1-benzopyran-2,9- dione (4), 8-benzyl-5,8 beta,9 beta-trihydroxy-6-methyl-4-phenyl-8,9-dihydro- furo[2,3-h]-1-benzopyran-2-one (5), 8-benzyl-5,8 beta,9 alpha-trihydroxy-6-methyl-4-phenyl-8,9-dihydro- furo[2,3-h]-1-benzopyran-2-one (6) and 5,11-dihydroxy-6-methyl-4-phenyl-11-(1-phenylmethyl)-7,10-dioxocane [5,6-h]-1-benzopyran-2,12-dione (7). For these compounds we propose the trivial names interruptins A-F. Compounds 1, 5/6 and 7 showed antibacterial activity while compounds 1 and 2 were cytotoxic to a KB cell line.     

Teratogenicity in rats of two dopaminergic agonists

The teratogenic potential of 2 structurally related dopaminergic agonists, BRL 16644 (2-[[3,4-dihydro-2,2-dimethyl-4-[3-(trifluoromethyl)phenyl]-2H- 1-benzopyran-7-yl]oxy]-N,N-dimethyl-Ethanamine: Chemical Abstracts No. 59257-18-0) and BRL 16657 (2-[[3,4-dihydro-2,2-dimethyl-4-[4-(trifluoromethyl)phenyl]-2H- 1-benzopyran-7-yl]oxy]-N,N-dimethyl-Ethanamine: Chemical Abstracts No. 59257-24-8), has been investigated in pregnant Sprague-Dawley rats. These compounds were administered orally from Days 6 to 15 of gestation inclusive at dose levels of 10, 20 and 40 mg/kg/day for BRL 16644 and 10, 20 and 35 mg/kg/day for BRL 16657. At caesarean section on Day 21 of gestation increased post-implantation loss, reduced foetal weights and high incidences of gross abnormalities were found with both compounds at their high dose levels. Maternal toxicity was evident at the intermediate and high dose levels but teratogenic effects extended to the low dose of each compound where treatment was well tolerated by the dams. The maternal effects were thought to be due to the dopamine potentiating properties of BRL 16644 and BRL 16657. When pimozide, a specific dopamine antagonist, was co-administered with BRL 16657 the maternal effects were considerably reduced and, although teratogenicity remained, effects of BRL 16657 on the embryo were extensively modified. This suggests that at least certain of the abnormalities were associated with prolonged dopamine potentiation. Pimozide alone was not teratogenic.     

Verbindungen mit potentiell positiv inotroper Wirkung, 2. Mitt. Synthese von 3,4-Dihydro-2-[(3-oxo-1-cyclopenten-1-yl)amino]-1(2H)-phenanthron und 3-(1,2,3,4-Tetrahydro-1-hydroxy-2-phenanthrylamino)-2-cyclopentenon

Compounds with Potentially Positive Inotropic Activity, II: Synthesis of 3,4-Dihydro-2-[(3-oxo-1-cyclopenten-1-yl)amino]-1(2H)-phenanthrone and 3-(1,2,3,4-Tetrahydro-1-hydroxy-2-phenanthrylamino)-2-cyclopentenone The synthesis of the title compounds from 1,3-cyclopentanedione and 2-amino-3,4-dihydro-1(2H)-phenanthrone and 2-amino-1,2,3,4-tetrahydro-1-phenanthrole is described.     

Synthesis and anticoagulant activities of substituted 2,4-diketochromans, biscoumarins, and chromanocoumarins

Different substituted 2,4-diketochromans, biscoumarins, and chromanocoumarins are the final products when 4-hydroxycoumarin and aromatic aldehydes containing hydroxyl group in o-, m,- or p-position condense in boiling ethanol. We synthesized 14 compounds. Three of them are described for the first time. The X-ray crystal structure analysis of 3-[6-oxo-(6H, 7H)-benzopyrano[4,3-b]benzopyran-7-yl]-4-hydroxy-2H-1-benzopyran-2-one 1 confirmed the structure of this compound. Acute toxicity studies of the compounds were performed on mice by oral and intraperitoneal administration. A comparative pharmacological study of the in vivo anticoagulant effect of the derivatives with respect to warfarin showed that the synthesized compounds have different anticoagulant activities. The most prospective compounds are 3-(3'-hydroxybenzylidene)-2,4-diketochroman 4 and 3,3'-(2-pyridylmethylene)-bis-4-hydroxy-2H-1-benzopyran-2-one 11 with low toxicity and dose-dependent anticoagulant activity in vivo.     

芫花根中新双香豆素的分离与鉴定

目的研究芫花根(Daphne genkwa)的化学成分。方法采用硅胶和Sephadex LH-20柱色谱技术进行分离纯化，运用多种波谱分析进行结构鉴定。结果分离得到一个新的双香豆素异西瑞香素，结构被确认为7-羟基-6-甲氧基-4［(2-氧杂-2H-1-苯并吡喃-7-基)-氧基］-2H-1-苯并吡喃-2-酮。结论异西瑞香素(isodaphnoretin)为一个新化合物。     

Synthesis and Ca2+ antagonistic activity of 2-[2-[(aminoalkyl)oxy]-5-methoxyphenyl]-3,4-dihydro-4-methyl-3-oxo-2H- 1,4-benzothiazines

As an extension of the previous investigation (J. Med. Chem. 1988, 31, 919), we synthesized a series of 2-[2-[(aminoalkyl)oxy]-5-methoxyphenyl]-3,4-dihydro-4-methyl-3-oxo-2H- 1,4-benzothiazines (3) and evaluated their Ca2+ antagonistic activities. Ca2+ antagonistic activity was measured with isolated depolarized guinea pig taenia cecum. On the basis of their potent Ca2+ antagonistic activity, six benzothiazines were selected and further evaluated for their vasocardioselectivity. Among these six compounds, the key compound 15 [3,4-dihydro-2-[5-methoxy-2-[3-[N-methyl-N-[2-[3,4- (methylenedioxy)phenoxy]ethyl]amino]propoxy]phenyl]-4-methyl-3-oxo- 2H-1,4-benzothiazine hydrogen fumarate] was recognized as having the lowest cardioselectivity. Following optical resolution, the absolute configuration of the compound's optically active enantiomer was determined by means of X-ray crystallography of a synthetic precursor (+)-4a. The Ca2+ antagonistic activity of 15 was found to reside primarily in (+)-15 (which was about 7 times more potent than (-)-15). The in vitro study showed that (+)-15 had a low cardioselectivity compared to verapamil and diltiazem. This result suggests that (+)-15 would exhibit less adverse effects due to cardiac inhibition than diltiazem and verapamil in therapeutic use.     

Synthesis, spectroscopy and alkylating properties of Pd(II) complexes of phosphorohydrazones of coumarin and chromone with potential antibacterial activity

Novel palladium(II) complexes (4-6) have been synthesized from the reaction of (E)-3{[(diethoxythiophosphoryl)-methylhydrazone]-methylene}-4-hydroxy-2H-1-benzopyran-2-one (1), E)-3-{[(dimethoxythiophosphoryl)-methylhydrazine]-methylidene}-3,4-dihydro-2H-1- benzopyran-2,4-dione (2) and (E)-3-{[(diethoxythiophosphoryl)-hydrazone]-methylene}- 4H-1-benzopyran-4-one (3), respectively, with PdCl2(PhCN)2. These complexes have been characterized by elemental analysis and spectroscopic studies. The alkylating activity of the complexes was examined in vitro toward 4-(4'-nitrobenzyl)pyridine (NBP test). The palladium(lI) complexes were found to possess alkylating activity. The compounds (4-6) have been screened for their antibacterial properties and displayed low activity.     

Synthesis and cardiotonic activity of 2-substituted 5-cyano-1,6-dihydro-6-oxo-3-pyridinecarboxylic acids and their methyl or ethyl esters.

The synthesis of ethyl or methyl esters of 5-cyano-1,6-dihydro-6-oxo-3- pyridinecarboxylic acids carrying as 2-substituent a polar group such as CO2C2H5, (CH2)2CO2CH3, (CH2)3CO2C2H5, CH2OCH3, or CF3 group is described. Also 2-[5-cyano-1,6-dihydro-2-(1,1-dimethylethyl)-6-oxo-3-pyridyl]-2- oxoacetic acid and 2,5,6,8-tetrahydro-2,5-dioxo-1H-thiopyrano[3,4-b]pyridine-3-carbon itrile were prepared. Nearly all the above esters gave routinely the corresponding carboxylic acids by alkaline hydrolysis followed by acidification. As milrinone analogues, the above compounds were tested on contractile activity and frequency rate of spontaneously beating atria from reserpine-treated guinea-pigs. 5-Cyano-2-trifluoromethyl-1,6- dihydro-6-oxo-3-pyridinecarboxylic acid and, in a lesser degree, the relative ethyl ester showed an appreciable positive inotropic activity, although inferior to that of milrinone.     

Dihydropyridazinone cardiotonics: the discovery and inotropic activity of 1,3-dihydro-3,3-dimethyl-5-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)-2H -indol-2- one

We discovered that 6 (N-[4-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)phenyl]acetamide) is a potent positive inotrope in dogs, and we have prepared several lactam analogues of this agent. These included 16 (1,3-dihydro-5-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)-2H-indol-2-one), 32 (the analogous quinolin-2-one), and 37 (the analogous benzazepin-2-one). The inotropic ED50's of these compounds were 24, 3.3, and 5.2 micrograms/kg, respectively, after iv administration to pentobarbital-anesthetized dogs. Compound 20 (LY195115, 1,3-dihydro-3,3-dimethyl-5-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)-2H-i ndol-2- one), the geminal dimethyl analogue of 16, was 3.5-fold more potent than 16 when administered iv (ED50 = 6.8 micrograms/kg). However, the most profound effect of the geminal alkyl substitution was on oral activity. The approximate ED50's of 20 and 16 after oral administration to conscious dogs were 25 and 400 micrograms/kg, respectively. The increase in contractility produced by 25 micrograms/kg of 20 was maximally sustained in excess of 8 h. Thus, 20 is one of the most potent and long-acting oral inotropes described to date.     

Structural identification and characterization of impurities in moxifloxacin

In the synthesis of Moxifloxacin four prominent impurities were detected in HPLC analysis. These impurities were detected in gradient HPLC method. They were isolated from enriched mother liquors and were characterized as 1-cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-7-[(S,S)-N-methyl-2,8-diazabicyclo (4,3,0) non-8yl]-4-oxo-3-quinoline carboxylic acid (Impurity-1), methyl-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-7-[(S,S)-2,8-diazabicyclo(4,3,0)non-8-yl]-4-oxo-3-quinoline carboxylate (impurity-2), and 1-cyclopropyl-6-fluoro-1,4 dihydro-8-hydroxy-7-[(S,S)-2,8-diazobicyclo(4,3,0)non-8-yl]-4-oxo-3-quinoline carboxylicacid (impurity-3), 1-cyclopropyl-6,7-difluoro-8-hydroxy-4-oxo-1,4 dihydro-3-quinoline carboxylicacid (impurity-4) by means of ¹H, ¹³C NMR, DEPT, IR and mass spectral data. Structural elucidation by spectral data was discussed.     

Evaluation of WO-2012085582 and WO-2012085583 two identified MABAs: backups to AZD-2115?

These two patent applications each claim combination formulations comprising a single dual-acting muscarinic antagonist/beta 2 agonist (MABA), as a free base or salt, with a second class of drug and the use of these formulations for the treatment of asthma and COPD. The two specified compounds are close analogues of each other and were originally disclosed in the same patent application. They are, respectively, 3-(2-chloro-3-((4-(2-ethylthiazole-4-carbonyl)-1-oxa-4,9-diazaspiro[5.5]undecan-9-yl)methyl)phenethoxy)-N-cyclopentyl-N-(2-(2-(5-hydroxy-3-oxo-3,4-dihydro-2H-benzo[b]{1,4] oxazin-8-yl)ethylamino)ethyl)propanamide and N-butyl-N-(2-(2-(5-hydroxy-3-oxo-3,4-dihydro-2H-benzo[b][l,4]oxazin-8-yl)ethylamino)ethyl)-3-(3-(2-(4-(2-isopropylthiazole-4-carbonyl)-1-oxa-4,9-diazaspiro[5.5]undecan-9-yl)ethyl)phenethoxy)propanamide.     

Synthesis and antihypertensive activity of 4-(1,2-dihydro-2-oxo-1-pyridyl)-2H-1-benzopyrans and related compounds, new potassium channel activators

The synthesis and antihypertensive activity of 4-(1,2-dihydro-2-oxo-1-pyridyl)-2H-1-benzopyran-3-ols are described. The unsubstituted pyridone adduct lead compound 7e is highly active, with substituents on the pyridone ring leading to a decrease in activity. Strongly electron-withdrawing substituents at the C-6 position are required for optimal activity. When the 2-pyridone ring is replaced by other heterocycles such as 4-pyridone, pyrimidone, pyridazinone, pyrazinone, and 1,4-butanesultam, the activity is maintained. The removal of the 3-hydroxy function (----17a) does not significantly reduce the activity. The elimination of water from the chromanols leads to the formation of the chromenes, which are among the most potent antihypertensives known. The influence of diverse substituents, in particular heterocyclic C-6 substituents, was investigated in the 4-(2-oxo-1-pyrrolidinyl)chroman-3-ol series. Chromanols esterified at the 3-hydroxy group with short-chain acids, maintain their activity. The epoxidation of the chromene double bond also produces active compounds. The rearrangement of the epoxides 22 produces the 3-keto compounds 23 and the enol derivatives 25. The reduction of the ketone 23a produces cis-chromanol 7ab along with its trans isomer 7e. All compounds were tested for oral antihypertensive activity in spontaneously hypertensive rats with a dose of 1 mg/kg; for selected compounds ED30 values as well as the duration of the antihypertensive effect were determined. 4-(1,2-Dihydro-2-oxo-1-pyridyl)-2,2-dimethyl-2H-1-benzopyran-6- carbonitrile (18a) is under development as a coronary vasodilator and a drug for treating angina pectoris.     

Two new compounds and anti-HIV active constituents from Illicium verum

Two new compounds named illiverin A (1) and tashironin A (8) were isolated from the roots of Illicium verum, together with seven known compounds: 4-allyl-2-(3-methylbut-2-enyl)-1,6-methylenedioxybenzene-3-ol (2), illicinole (3), 3-hydroxy-4,5-methylenedioxyallyl-benzene (4), (-)-illicinone-A (5), 4-allyl-4-(3-methylbut-2-enyl)-1,2-methylenedioxycyclohexa-2,6-dien-5-one (6), 3,4-seco-(24 Z)- cycloart-4(28),24-diene-3,26-dioic acid, 26-methyl ester (7) and tashironin (9). Based on 1D- and 2D-NMR data (COSY, HMQC, HMBC), the structures of the new compounds were deduced to be (E)-1-[(3-methylbut-2-enyl)oxy]-2-methoxy-4-(prop-1-enyl)benzene (1) and 11-O-debenzoyl-11alpha-O-2-methylcyclopent-1-enecarboxyltashironin (8). Compounds 1-9 were screened for anti-HIV activity in vitro whereby compounds 5 and 7 possessed moderate anti-HIV activity with EC50 values of 16.0 and 5.1 microM with SI values of 18.2 and 15.6, respectively.     

Rational design, synthesis, and biological activity of benzoxazinones as novel factor Xa inhibitors

Inappropriate thrombus formation within blood vessels is the leading cause of mortality in the industrialized world. Factor Xa (FXa) is a trypsin-like serine protease that plays a key role in the blood coagulation cascade and represents an attractive target for anticoagulant drug development. From a high-throughput in vitro mass screen of our chemical library, we identified 4-[5-[(2R,6S)-2, 6-dimethyltetrahydro-1(2H)-pyridinyl]pentyl]-2-phenyl-2H-1, 4-benzoxazin-3(4H)-one (1a) as an inhibitor of FXa with an IC(50) of 27 microM. Through a combination of SAR studies and molecular modeling, we synthesized 3-(4-[5-[(2R,6S)-2, 6-dimethyltetrahydro-1(2H)-pyridinyl]pentyl]-3-oxo-3,4-dihydro-2H- 1,4-benzoxazin-2-yl)-1-benzenecarboximidamide (1n) which was a potent FXa inhibitor with an IC(50) of 3 nM. This compound exhibited high selectivity for FXa over other related serine proteases and was efficacious when dosed intravenously in rabbit and dog antithrombotic models.