WO1997048686A1

WO1997048686A1 - Novel n-1 alkyl-2-oxo-2,3,4,5-tetrahydro-1h-1,5-benzodiazepin-3-yl)-3-amides

Info

Publication number: WO1997048686A1
Application number: PCT/US1997/010192
Authority: WO
Inventors: Harold G. Selnick; David A. Claremon; Nigel Liverton
Original assignee: Merck & Co., Inc.
Priority date: 1996-06-21
Filing date: 1997-06-17
Publication date: 1997-12-24
Also published as: AU3389997A

Abstract

This invention is concerned with novel compounds represented by structural formula (I) which are useful in the treatment of arrhythmia.

Description

TITLE OF THE INVENTION

NOVEL N-l ALKYL-2-OXO-2,3,4,5-TETRAHYDRO- lH- l ,5-BENZODIAZEPIN-3YL)-3-AMIDES

BACKGROUND OF THE INVENTION

Arrhythmias often occur as complications to cardiac diseases such as myocardial infarction and heart failure. In a serious case, arrhythmias give rise to a ventricular fibrillation and can cause sudden death.

Though various antiarrythmic agents are now available on the market, agents which exhibit both satisfactory effects and high safety profiles have not been marketed. For example, antiarrythmic agents of Class I, according to the classification of Vaughan-Williams, which cause a selective inhibition of the maximum velocity of the upstroke of the action potential (Vmax) are inadequate for preventing ventricular fibrillation.

In addition, they have problems regarding safety, namely, they cause a depression of the myocardial contractility and have a tendency to induce arrythmias due to an inhibition of the impulse conduction. Beta-adreno- ceptor blockers and calcium antagonists which belong to Class II and IV respectively, have a defect in that their effects are either limited to a certain type of arrhythmia or are contraindicated because of their cardiac depressant properties in certain patients with cardiovascular disease. Their safety, however, is higher than that of the antiarrhythmic agents of Class I.

Antiarrythmic agents of Class III are drugs which cause a selective prolongation of the duration of the action potential without a significant depression of the Vmax. Drugs in this class are limited. Examples such as sotalol and amiodarone have been shown to possess Class III properties. Sotalol also possesses Class II effects which may cause cardiac depression and be contraindicated in certain susceptible patients. Also, amiodarone is severely limited by side effects. Drugs of this class are expected to be effective in preventing ventricular fibrillations. Pure Class III agents, by definition, are not considered to cause myocardial depression or an induction of arrhythmias due to the inhibition of the action potential conduction as seen with Class I antiarrhythmic agents.

SUMMARY OF THE INVENTION

This invention is concerned with novel compounds represented by structural formula I

*

FORMULA I

R!and R2 are independently

1 ) phenyl, either unsubstituted or substituted with one or two substituents selected from a) -N02, OH, b) -Cl, Br, F, or I, c) -CF3, d) -Cl-3 alkyl, e) -Cl -3 alkoxy, f) -CN, g) -methylenedioxy, and

Z is

1) Ci -6 alkyl, either straight or branched chain ,

2) substituted Cl -6 alkyl, either straight or branched chain, wherein the substituents are selected from F, OH, N02,

2) C2-4 alkenylene, either straight or branched chain, 3) -(CH2)m-W-(CH2)n- wherein m and n are independently 0, 1 , 2, 3 or 4 and W is -0-, -S- or -NH,

4) C3-6 cycloalkane,

5) C3-6 cycloalkylene, or

6) single bond;

or pharmaceutically acceptable salts, hydrates and crystal forms thereof, which are useful as antiarrhythmic agents.

The compounds of the present invention may have asymmetric centers and occur as racemates, mixtures of enantiomers, individual diastereomers, or as individual enantiomers with all isomeric forms being included in the present invention. The invention is also concerned with pharmaceutical formulations comprising one of the novel compounds as an active ingredient.

The invention is also concerned with a method of treating arrhythmia by the administration of one or a combination of the novel compounds or formulation thereof to a patient in need of such treatment.

DETAILED DESCRIPTION OF THE INVENTION

This invention is concerned with novel compounds represented by structural Formula 1 :

FORMULA I

R land R² are independently

1 ) phenyl, either unsubstituted or substituted with one or two substituents selected from a) -N02, OH, b) -Cl, Br, F, or I, c) -CF₃, d) -Cl-3 alkyl, e) -Cl -3 alkoxy, f) -CN, g) -methylenedioxy, and

Z is

1 ) Cl -6 alkyl, eithei

2) substituted Cl -6 < chain, wherein the substituents are selected from F, OH, N02,

2) C2-4 alkenylene, either straight or branched chain,

3) -(CH2)m-W-(CH2)n- wherein m and n are independently 0, 1 , 2, 3 or 4 and W is -O-, -S- or -NH,

4) C3-6 cycloalkane,

5) C3-6 cycloalkylene, or

6) single bond; or pharmaceutically acceptable salts, hydrates and crystal forms thereof, which are useful as antiarrhythmic agents. The compounds of the present invention may have asymmetric centers and occur as racemates, mixtures of enantiomers, individual diastereomers, or as individual enantiomers with all isomeric forms being included in the present invention. The invention is also concerned with pharmaceutical formulations comprising one of the novel compounds as an active ingredient.

The invention is also concerned with a method of treating arrhythmia by the administration of one or a combination of the novel compounds or formulation thereof to a patient in need of such treatment. These compounds include pharmaceutically acceptable crystal forms and hydrates of the compounds of Formula I, which are antiarrhythmic agents.

A preferred embodiment of this invention is represented by ^T

R2 are independently

1 ) phenyl, either unsubstituted or substituted with one or two substituents selected from a) -N02, OH, b) -Cl, Br, F, or I, c) -CF3, d) -Cl -3 alkyl, e) -Cl -3 alkoxy, f) -CN, g) -methylenedioxy, and

Z is

1 ) Cl-6 alkyl, either straight or branched chain ,

2) C2-4 alkenylene, either straight or branched chain,

3) -(CH2)m-W-(CH2)n- wherein m and n are independently 0, 1 , 2, 3 or 4 and W is -0-, -S- or -NH,

4) C3-6 cycloalkane,

5) C3-6 cycloalkylene, or

6) single bond; or pharmaceutically acceptable salts, hydrates and crystal forms thereof, which are useful as antiarrhythmic agents.

A more preferred embodiment of this invention is represented by

where R2 is phenyl, either unsubstituted or substituted with one or two substituents selected from a) -N02, OH, b) -Cl, Br, F, or I, c) -CF3, d) -Cl -3 alkyl, e) -Cl-3 alkoxy, f) -CN, g) -methylenedioxy.

One preferred embodiment of the present invention is (+)-2-[2,4-Bis(trifluoromethyl)phenyl]-N-[3R-2,3-dihydro-l -(t-butyl)- 2-oxo-5-phenyl-lH-benzo[e]ll,4]diazepin-3-yl]acetamide

Still another preferred embodiment of the present invention is (+)-2-[2,4-Bis(chloro)pheny l]-N-[3R-2,3-dihydro- 1 -(t-butyI)-2-oxo-5- phenyl-lH-benzo[e]f l ,4]diazepin-3-ylJacetamide

The novel compounds of this invention may be synthesized using the reactions taught in the following schemes:

SCHEME I

A

In the above scheme, R2 is selected from the following:

where X, YH and Z are independently: Cl, Br, Me, OH3, CF3, CF3O, Cθ2alkyl, where alkyl is C1 -C6 either straight or branched chain.

Resolution of the compounds produced is accomplished using the procedure as shown in Scheme II.

Scheme II

where R2 is for example

The novel compounds of the present invention, have the pharmacological properties required for antiarrhythmic agents of Class III, namely the prolongation of the myocardial action potential in vitro, without a significant depression of the Vmax, and the prolongation of QTc -interval in anesthetized dogs.

These compounds are effective in treating and preventing all types of arrhythmias including ventricular and atrial (supraventricular) arrhythmias. The compounds of the present invention are especially useful to control reentrant arrhythmias and prevent sudden death due to the ventricular fibrillation. These compounds are also effective in treating and preventing impaired cardiac pump functions.

In the novel method of this invention of treating arrhythmia, one of the compounds or pharmaceutically acceptable salt thereof, is administered in an amount ranging from about 0.0001 to about 20 mg per kg of body weight per day, preferably from about 0.001 to about 5.0 mg per kg of body weight per day in a single dose or in 2 to 4 divided doses.

These compounds, or pharmaceutically acceptable salts thereof, in the described dosages, are administered orally, intraperitone- ally, subcutaneously, intramuscularly, transdermally, sublingually or intravenously. They are preferably administered intravenously or orally, for example in the form of tablets, troches, capsules, elixirs, suspensions, emulsions, syrups, wafers, chewing gum, or the like prepared by art recognized procedures. The amount of active compound in such therapeutically useful compositions or preparations is such that a suitable dosage will be obtained.

These compounds can be administered as the sole active ingredient or in combination with other antiarrhythmic agents or other cardiovascular agents, such as Class I, Class II or Class IV antiarrhythmic agents, vasodilators, angiotensin converting enzyme inhibitors, angiotensin II antagonists, diuretics or digitalis.

These compounds can be administered as a method of treat- ing arrhythmia and impaired cardiac pump functions in conjunction with defibrillators, including implantable defibrillators. These compounds reduce the frequency of defibrillator firing.

By Class I antiarrhythmic agents is meant those agents which provide for sodium channel blockade, including those compounds which exert a membrane stabilizing effect. Exemplary of this class of compounds are quinidine, procainamide, disopyramide, lidocane, tocainide, flecainide and propafenone. By Class II antiarrhythmic compounds is meant those agents which block sympathetic activity. Exemplary of this class of compounds are propranolol and acebutolol. By Class III antiarrhythmic agents is meant those compounds which prolong the effective refractory period without altering the resting membrane potential or rate of depolar¬ ization. In addition to the novel compounds of this invention, compounds such as amiodarone, bretylium and sotalol are considered to be in this class. Class IV antiarrhythmic agents are effective in calcium channel blockade. Exemplary of this class of compounds are diltiazem and verapamil. Further definition of these classes can be found in Pharma Projects, section C1B, May 1993, which is hereby incorporated by reference.

Exemplary of vasodilators are compounds such as papaverine and isosorbide dinitrat. Examples of angiotensin converting enzyme inhibitors include enalapril, lisinopril and captopril. Examples of diuretics include hydrochlorothiazide and acetazolamide. The pharmaceutical agents listed herein are examples and do not represent a complete listing of the many compounds in these classes which are contemplated by this invention.

The activity of the compounds described herein as antiarrhyth¬ mic agents is measured by their ability to block the IKs and IKr currents as determined by the following test protocol.

Outward potassium currents are measured in single guinea O 97/48686 PC17US97/10192

- 12 -

pig ventricular myocytes using a whole-cell voltage clamp technique described in detail elsewhere (Sanguinetti and Jurkiewicz, 1990, Two components of cardiac delayed rectifier K⁺ current: differential sensitivity to block by Class III antiarrhythmic agents. J. Gen Physiol. 96: 195-215). Myocytes are isolated by enzymatic (collagenase and protease) digestion of Langandorf perfused hearts. Single cells are then voltage clamped using 1 mm square-bore pipettes filled with 0.5 M Kgluconate, 25 mM KC1, 5 mM K(2)ATP. Cells are bathed in a solution containing, in mN: 132 NaCl, 4KC1, 1.2 MgCl[2], 10 HEPES, 10, glucose: pH 7.2, temp. 35°C.

Each cell is maintained at a holding potential of -50 mV. Test depolarizations are applied as voltage ramps from -85 to -50 mV, and as steps to -10 mV (0.5 s) and +50 mV (1.0 s). IKI is measured as peak outward current during the voltage ramp. IKr is measured as tail currents upon repolarization from -10 mV to -50 mV. IKs is measured as time-dependent current during the pulse to +50 mV. Currents are measured during control, then after exposure to drug at two different concentrations.

Employing this test the compounds described herein have an IC50 of less than 1 ,000 nM as IKs blockers. The compounds of this invention are at least 10 times more potent in the blockade of IKs than the blockade of IKr.

Examples

In the following examples, reference is made to the steps outlined of the schemes found in the Detailed Description of the Invention. For example, "Step I-A" refers to Step A of Scheme I. Example 1

Preparation of:

(-)-2-[2,4-Bis(trifluoromethyl)phenyl)-N-[2,3-dihydro-2-oxo-5-phenyl- l-(t-butyl)-l H-benzo[e][ l,4]diazepin-3-yl]acetamide

t-butyl alcohol

Step 1A

N-Tertbutyl-2-aminobenzophenone

To a solution of 2-aminobenzophenone (40.0g, 0.203 mole) in tert-butyl alcohol (1.0 1) at 25°C and under nitrogen was slowly added sulfuric acid (100 ml). The mixture was warmed to 50°C for 7 days, cooled, concen¬ trated in vacuo and the mixture quenched into a mixture of water (0.5 1) and ethyl acetate (1.0 1). The pH was adjusted slowly to 8.5 with 10M NaOH. The ethyl acetate layer was removed, washed with 10% aqueous sodium bicarbonate (500 ml) dried over sodium sulfate and concentrated to give a thick oil. The oil was chromatographed on silica using 8% ethyl acetate/hexane to give 45.4 g.

1H NMR (300 MHz, CDC1₃) δ 9.0 (s, 1H), 7.3-7.6 (m, 7H), 7.0 (d, 1H), 6.48 (t, 1H), 1.45 (s, 9H).

Step IB

N-f2-Benzoylphenyl)-2-bromo-N-tert-butyl-acetamidc

To a solution of N-tert-butyl-2-aminobenzoρhenone (44.5 g, 0.176 mole) in methylene chloride (450 ml) at 0°C and under nitrogen was added bromoacetyl bromide (16.9 ml, 0.193 mole). The reaction was allowed to stir for 30 minutes and solid sodium bicarbonate (50 g, 0.6 mole) added. Water (5 ml) was added and the reaction was stirred well for 30 minutes after which additional bromoacetyl bromide (7.7 ml, 0.088 mole) and sodium bicarbonate (22.0 g, 0.264 mole) were added. This addition of bromoacetyl bromide and sodium bicarbonate was repeated at 30 minute intervals an additional two times after which the methylene chloride layer was removed and the aqueous layer washed with methylene chloride (200 ml). The methylene chloride extracts were combined, dried over sodium sulfate, filtered and concentrated to give a foam. The foam was triturated from 5% ethyl acetate/hexane to give 58.0 g.

^lU NMR (300 MHz, CDCI₃) δ 7.84 (m, 2H), 7.4-7.8 (m, 7H), 3.88 (d, 1H, J = 1 1.2 Hz), 3.55 (d, 1H, J = 1 1.2 Hz), 1.45 (s, 9H).

Step 1C

2.3-Dihydro- 1 -(t-butyl)-2-oxo-5 -phenyl- 1H- 1 ,4-benzodiazepine To a solution of N-(2-benzoylphenyl)-2-bromo-N-tert-butyl-acetamide (55.0 g, 0.147 mole) in dimethylformamide (500 ml) under nitrogen at 15°C was added sodium iodide (24.3 g, 0.162 mole) followed by sodium azide (14.33 g, 0.22 mole). The mixture was allowed to stir for 15 minutes then warmed to 50°C for 1.5 hours. The reaction was cooled, quenched into water (2.5 1) and extracted with ethyl acetate (1.0 1). The aqueous layer was washed with ethyl acetate (1.0 1) and then the ethyl acetate extracts washed with water (2x500 ml). The ethyl acetate extracts were dried over sodium sulfate, filtered and concentrated to give an oil. The oil was dissolved in tetrahydrofuran (1.0 1) and ethanol (1.0 1) and the mixture hydrogenated (1 atm) using 10% palladium on carbon (2.0 g) for 1.5 hours. The reaction was filtered and concentrated to give an oil. The oil was dissolved in toluene (600 ml) and p-toluenesulfonic acid (100 mg) added. The solution was warmed to reflux (1 hour) and a dean-stark trap utilized to collect water (12 ml). The reaction was cooled, washed with 5% aqueous sodium bicarbonate (200 ml), dried over sodium sulfate, filtered and concentrated to give an oil 40.0 g.

ⁱH NMR (300 MHz, CDCI₃) δ 7.70 (m, 2H), 7.3-7.5 (m, 7H), 4.58 (d, 1H, J = 1 1.2 Hz), 3.70 (d, IH, J = 1 1.2 Hz), 1.41 (s, 9H).

Step ID

3-Azido-5-phenyl-l-(t-butyl)-lH-benzoleiπ .41diazepine

To a solution of 2,3-dihydro-l -(t-butyl)-2-oxo-5-phenyl-lH-l ,4-benzo- diazepine (15.0 g, 0.051 mole) in THF at -78°C and under nitrogen was slowly added 1.0 M potassium t-butoxide (1 15 ml, 0.1 13 mole) in THF. The reaction was stirred at -78°C for 10 minutes and triisopropylbenzene sulfonylazide (17.4 g, 0.056 mole) in THF (170 ml) added. The reaction was stirred for 2 minutes and then quenched by addition of acetic acid (13.5 ml). The mixture was allowed to warm to room temperature, stirred for 1 hour, diluted with ethyl acetate (1.0 1) and 10% aqueous sodium bicarbonate (500 ml) mixed well and ethyl acetate layer removed. The aqueous extract was washed with ethyl acetate (2 x 500 ml), organics combined, dried over sodium sulfate, filtered and concentrated to give a foam. The foam was chromatographed on silica using 20% ethyl acetate/ hexane to give upon concentration of product containing fractions, 13.1

S-

iH NMR (300 MHz, CDC1₃) δ 7.68 (m, 2H), 7.0-7.6 (m, 7H), 4.42 (s, IH), 1.42 (s, 9H).

Step IE

3-Amino-5-phenyl-l -(t-butyl)-lH-benzorel[ 1.4ldiazepine

To a solution of 3-azido-5-phenyl-l -(t-butyl)-lH-benzo[e][l ,4]diazepine (12.0 g, 0.036 mole) in ethanol (500 ml) and THF (30 ml) was added 10% palladium on carbon (1.2 g) and the mixture stirred under hydrogen (1 atm) for 2- 1/2 hours. The reaction was filtered and concentrated to a foam (1 1.2 g).

m NMR (300 MHz, CDCI₃) δ 7.7 (m, 2H), 7.2-7.5 (m, 7H), 4.40 (s, IH), 2.3 (brS, 2H), 1.40 (s, 9H).

Step IF

2R-2- Amino-Nr2-oxo-5-phenyl- 1 -f t-butvn-2.3-dihvdro- 1 H- benzofel 11.4]diazepin-3-yl)-3-phenylpropionamide

To a mixture of 3-amino-5-phenyl-l -(t-butyl)-l H-benzo[e][l ,4]diazepine (1 1.2 g, 0.036 mole), 1-hydroxybenztriazole hydrate (7.75 g, 0.050 mole), triethylamine (7.0 ml, 0.050 mole) and N-(carbobenzyloxy)-D- phenylalanine (1 1.84 g, 0.040 mole) in dimethylformamide (112 ml) was added l -(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (9.62 g, 0.050 mole). The mixture was stirred for 18 hours and then quenched into a mixture of 10% aqueous citric acid (500 mL) and ethyl acetate (1.0 1). The ethyl acetate layer was separated and washed with water (500 ml), 10% aqueous sodium bicarbonate (500 ml), dried over sodium sulfate, filtered and concentrated to an oil (21.2 g). The oil was dissolved in ethanol (800 ml), 10% palladium on carbon added (2.5 g), and mixture stirred under hydrogen for 3 hours. The mixture was filtered and concentrated to a foam (16.4 g). The foam was chromatographed on silica using ethyl acetate. The earlier eluting diasteromer (Rf = 0.4) was collected until the eluting product contained < 2.5 % of the lower eluting (Rf = 0.2) diastereomer. Concentration of the fraction gave a foam (5.0 g). The foam was crystallized from diethyl ether (75 ml) to give 4.0 g pure compound (diastereomer ratio by HPLC (C-18-Waters) > 99% ee).

Step 1G

(V)-3-Amino-5-phenyl-l -(t-butyl)-lH-benzoleiπ .41diazepine

To a solution of 2R-2-amino-N[2-oxo-5-phenyl-l -(t-butyl)-2,3-dihydro- lH-benzo[eJ[l ,4]diazepin-3-yl)-3-phenylpropionamide (2.0 g, 0.0044 mole) in methylene chloride (20 ml) under argon was added phenylisothiocyanate (0.65 ml, 0.0053 mole). The mixture was stirred at 25 °C for 4 hours, concentrated to a foam in vacuo and cold (0°C) trifluoroacetic acid (25 ml) added. The resulting solution was stirred at +8°C under argon for 18 hours and then concentrated in vacuo at < 0°C to an oil The oil was chromatographed on silica using methylene chloride, methanol, acetic acid, water (90:10: 1 : 1). The product containing fractions were washed with 10% aqueous sodium bicarbonate, dried over sodium sulfate and concentrated to a foam (1.35 g).

α = +8.6° (MeOH, C = 0.22) HPLC Analysis > 99.4%ee Step IH

r-)-2-12.4-Bisιtrifluoromethvπphenyll-N-r2.3-dihvdro-2-oxo-5-phenyl- l -ft-butylVlH-benzofell L41diazepin-3-yllacetamide

To a mixture of (+)-3-amino-5-phenyl-l -(t-butyl)-lH- benzofel[ l ,4]diazepine (0.5 g, 0.00163 mole), 1 -hydroxybenztriazole hydrate (0.35 g, 0.00228 mole), triethylamine (0.23 ml, 0.00228 mole), and 2,4-bistrifluoromethylphenyl acetic acid (0.49 g, 0.00179 mole) in DMF (10 ml) was added l -(3-dimethylaminopropyl)-3- ethylcarbodiimide hydrochloride (0.44 g, 0.00228 mole). The mixture was stirred for 2.5 hours and then quenched into 10% aqueous citric acid (50 ml) and ethyl acetate (150 ml). The ethyl acetate layer was removed and washed with water (25 ml) followed by 10% aqueous sodium bicarbonate (50 ml). The ethyl acetate extract was then dried over sodium sulfate, filtered, concentrated to a foam, and chromatographed on silica using 25% ethyl acetate/hexane. Concentration of the product fractions gave a white foam (0.86 g). The foam was crystallized from 10% ethyl acetate/hexane to give the title compound as a white crystalline solid (0.527 g).

α = -5.47° (MeOH, C = 0.525) MP = 125-126°C

»H NMR (300 MHz, CDC1₃) δ 7.92 (s, IH), 7.79 (d, IH, J = 8.9 Hz), 7.70 (d, IH, J = 8.9 Hz), 7.20-7.67 (m, 9H), 5.39 (d, IH, J = 8.0 Hz),

3.93 (s, 2H), 1.42 (s, 9H).

2,4-Bis(trifluoromethyl)phenylacetic acid

Step 1A

2_<4-Bis(trifluoromethvDbenzonitrile To a stirring biphasic mixture of 100 mL ethanol and 250 mL of phosphate buffer (lg of NaH₂Pθ4*H2θ per 5 mL H2O adjusted to pH = 7.0 with 50% NaOH) and NaCN (81.3 mmol, 4.0 g) heated to 60°C was added 2,4-bis(trifluoromethyl)benzyl bromide (32.5 mmol, 10 g) in 50 mL EtOH dropwise over 30 minutes. The reaction was heated at 60°C for 24 hours. The reaction was then evaporated under reduced pressure. The remaining aqueous was extracted with 2x150 mL EtOAc. The organic layers were combined, dried with brine and Na₂S0₄. The organic phase was evaporated under reduced pressure and the residue chromatographed over silica eluting with 10% EtOAc:Hexanes. The pure fractions were collected and evaporated to give 7.0 g of a pale yellow oil.

ⁱH NMR (300 MHz, CDCI₃) δ 8.0-7.85 (m, 3H), 4.03 (s, 2H).

Step IB

2.4-Bis(trifluoromethyl)phenyl acetic acid

2,4-Bis(trifluoromethyl)benzonitrile (41.5 mmol, 10.51 g) was taken up in 100 mL acetic acid, 50 mL cone. H₂SO₄, and 20 mL water. This was heated to 120°C for 3 hours. The reaction was then diluted with IL ice water, and extracted with 2x300 mL ethyl acetate. The combined organics were washed with 2x200 mL water, dried with brine and Na2S0₄, and evaporated under reduced pressure. The residue was taken up in a minimum of diethyl ether and crystallized by adding sufficient hexane to precipitate the product. The solid was collected to give 7.74 g of 2,4-bis(trifluoromethyl)phenyl acetic acid was white crystals.

^lU NMR (300 MHz, CDCI3) δ 7.93 (s, IH), 7.80 (d, J = 7.9 Hz, IH), 7.55 (d, J = 7.9 Hz, IH), 3.94 (s, 2H).

Claims

WHAT IS CLAIMED IS:

1. A compound of the structural formula I

^V

Rland R2 are independently

1 ) phenyl, either unsubstituted or substituted with one or two substituents selected from a) -N02, OH, b) -Cl, Br, F, or I, c) -CF3, d) -Cl-3 alkyl, e) -Cl-3 alkoxy, f) -CN, g) -methylenedioxy, and

Z is

1 ) Cl-6 alkyl, either straight or branched chain ,

2) substituted Cl-6 alkyl, either straight or branched chain, wherein the substituents are selected from F, OH, Nθ2,

2) C2-4 alkenylene, either straight or branched chain,

3) -(CH2)m-W-(CH2)n- wherein m and n are independently 0, 1, 2, 3 or 4 and W is -0-, -S- or

-NH,

4) C3-6 cycloalkane,

5) C3-6 cycloalkylene, or

2. The compound of Claim 1 which is

R2 are independently

1 ) phenyl, either unsubstituted or substituted with one or two substituents selected from a) -N02, OH, b) -Cl, Br, F, or 1, c) -CF₃, d) -Cl -3 alkyl, e) -Cl-3 alkoxy, f) -CN, g) -methylenedioxy, and

Z is

1) Cl-6 alkyl, either straight or branched chain ,

2) substituted Cl-6 alkyl, either straight or branched chain, wherein the substituents are selected from F, OH, N02,

2) C2-4 alkenylene, either straight or branched chain,

4) C3-6 cycloalkane,

5) C3-6 cycloalkylene, or

6) single bond;

3. The compound of Claim 1 which is

where R2 is phenyl, either unsubstituted or substituted with one or two substituents selected from a) -N02, OH, b) -Cl, Br, F, or I, c) -CF₃, d) -Cl -3 alkyl, e) -Cl-3 alkoxy, f) -CN, g) -methylenedioxy.

4. The compound of Claim 1 which is

5. The compound of Claim 1 which is

6. A pharmaceutical formulation comprising a pharma¬ ceutically acceptable carrier and a therapeutically effective amount of the compound of Claim 1 or a pharmaceutically acceptable salt, crystal form or hydrate thereof.

7. The pharmaceutical formulation of Claim 6 comprising in addition another antiarrhythmic agent or other cardiovascular agent.

8. A method of preventing or treating arrhythmia which comprises the administration to a patient in need of such treatment of an antiarrhythmically effective amount of the compound of Claim 1.

9. The method of Claim 8 comprising the concomitant administration of another antiarrhythmic agent or other cardiovascular agent.