AU631801C - Bivalent ligands effective for blocking acat enzyme - Google Patents

Description

BIVALENT LIGANDS EFFECTIVE FOR BLOCKING ACAT ENZYME

Background of the Invention

The present invention is directed toward new bivalent ligands effective for blocking or inhibiting acyl-CoA: cholesterol O-acyltransferase enzyme (hereinafter, ACAT) which is a major regulator of cholesterol metabolism in cells. The blocking or inhibition of ACAT is useful in the prevention or treatment of a variety of physiological conditions associated with arterial vessels. The compounds of the present invention are paticularly useful in the prevention or treatment of the constriction or obstruction of arteries and atherosclerosis.

ACAT is found, in most tissues including arterial, liver, adrenal gland, mammary gland, ovaries and intestine where it readily converts cholesterol into esterified cholesterol. Bell, F.P., Arterial Cholesterol Esterification By AcylCoAcholesterol Acyltransferase: Significance in Atherogenesis and its Inhibition by Drugs, Pharmacological Control of Hyperlipidaemia, JR Prous Sci. Pub., pp 409-22 (1986) . Generally this reaction is in equilibrium with a hydrolysis reaction which converts the. esterified cholesterol into cholesterol. The amount of available cholesterol which effects the balance of this equilibrium is dependent on many physiological factors and diet. Unfortunately, esterified cholesterol does not migrate through tissue as easily as cholesterol and can build-up and form obstructions. The accumulation of esterified cholesterol is one of the characteristic features of atherosclerotic plaque. Therefore it would be of great advantage if the ACAT enzyme could be blocked or inhibited from turning cholesterol into esterified cholesterol in arterial tissues.

Information Disclosure

The literature discuss the use of ACAT inhibitors as potential antiatherosclerotic agents as disclosed in V.G. DeVries, et al. , J. Med. Chem., 29, 1131 (1986) and J. Med. Chem., 26, 1411 (1983). Also, the role of acyl-CoA:cholesterolacyltransferase in cellular cholesterol metabolism is discussed in K.E. Suckling and E.F. Stange, J. Lipid Res., 26, 647 (1985).

The subject bivalent ligands are represented by α-β-α where β is a chemical tether connecting two heterocyclic groups α. The heterocyclic groups are furochromones, furobenzoxazines and benzodifurans which are generally disclosed in U.S. Patents 4,284,569, 4,412,071 and 4, 304 , 722.

Summary of the Invention

The present invention is directed to a family of bivalent ligand compounds α-β-α formed from two heterocyclic compounds "α" connected by a tether "β" , structurally represented on the formula sheet below, wherein

X and Y are independently O , N or S;

A is C=CH-Z, N=C-Z or CR₅=C-(CH₂)_n-Z;

R₁ and R₂ are independently:

a) H,

b) halo,

c) alkyl,

d) -(CH₂)_p-aryl,

e) -(CH₂)p-heteroaryl,

f) -(CH₂)_p-CO₂R₆,

g) -(CH₂)_p-CONR₇R₈,

h) -Si(R₉),

i) -(CH₂)_n-NR₇R₈,

j) -(CH₂)_n-OR₁₀,

k) -CF₃, or

l) -(CH₂)_n-SR₆, -(CH₂)_n- (CH₂)_n-SO₂R₆;

R₃ is

a) OH,

b) OCH₂CH=CH₂,

c) OCH₂CH(OH)CH₂NHR₆,

d) -O-alkyl,

e) -O-(CH₂)_n-CO₂R₆, or

f) -O-(CH₂)_n-CONR₇R₈;

R₄ is

a) hydrogen,

b) halo,

c) NO₂,

d) NH₂,

e) CF₃,

f) alkyl,

g) aryl,

h) -S-alkyl or aryl,

i) -SO-alkyl or aryl, j) -SO₂-alkyl or aryl,

k) R₃, or

1) -(CH₂)_n-NR₇R₈;

Z is a primary, secondary or tertiary amine;

R₅ is a hydrogen, NO₂, NH₂, CF₃, alkyl, aryl, -S-alkyl, -S-aryl or heteroaryl, -SO-alkyl or aryl, -SO₂-alkyl or aryl, or R₃;

R₆ is H, CF₃, alkyl or aryl, Li⁺, Na⁺, K⁺, Ca²⁺ and other pharmaceutically acceptable counter ions for carboxylic acids ;

R₇ and R₈ are H, CO-alkyl, CO-aryl, alkyl, cycloalkyl, alkylaryl, aryl, heteroalkyl, aryl, or R₇ and R₈ can be taken together to form a piperidine ring or morpholine ring;

R₉ is an alkyl or aryl;

R₁₀ is H, CF₃, alkyl, aryl or heteroaryl; and

n is 0-5 and p is 0-8; and

β is selected from the group A-E wherein:

W is -CH₂-(X_n-CH₂)_n;

X is N, O or S;

R₁₁ is an alkyl, CO-alkyl or CON-alkyl or -aryl; and

m is 0-4, n is 0-5 and o is 1-5.

The preferred tethers are trimethylene-4,4-dipiperidine, 1,2-ethanediyl-4,4-dipiperidine, 1,4-bis(aminoproρylpiperazine), or 1,8-diaminooctane. One example of a bivalent ligand composition is 7,7'-[1,2-ethanediylbis(4,1-piperidinediylmethylene)]-bis[4,9-dimethyl-5H-furo[3,2-g] [1]-benzopyran-5-one.

In one aspect, the subject bivalent ligands provide a method for blocking or inhibiting ACAT enzyme by administering a pharmacological amount of the composition or an acceptable salt thereof to a subject including humans. The blocking or inhibition of ACAT is useful in the prevention or treatment of a variety of physiological conditions associated with arterial vessels. The method is particular suitable for administration subsequent to by-pass surgery, coronary by-pass surgery, angioplasty or transplants.

In another aspect, the subject bivalent ligands provide a method for preventing or treating atherosclerosis comprising administering a pharmacological amount of the composition or an acceptable salt thereof to a subject including humans.

Detailed Description of the Invention

The compounds of the present invention are bivalent ligands, represented by "α -β-α", such as bisaminofurochromone and bisaminoben- zodifurans formed from two heterocyclic ring structures "α" linked by a chemical tether "β" of varying composition. The heterocyclic structures "α", furochromones, furobenzoxazines and benzodifurans, are disclosed in U.S. Patents 4,284,569, 4,412,071 and 4,304,722 where they are reported to be antiatherogenic compounds having antiatherosclerosis activity. Their synthesis are disclosed in U.S. Patents 4,284,569, 4,412,071 and 4,304,722 which are herein incorporated by reference. The heterocyclic compounds can be generically depicted by the structural formula "α" as shown on the formula sheet below; wherein

X and Y are independently O, N or S;

A is C=CH-Z, N=C-Z or CR₅=C- (CH₂)_n-Z;

R₁ and R₂ are independently:

a) H,

b) halo,

c) alkyl,

d) -(CH₂)_p-aryl,

e) -(CH₂)p-heteroaryl,

f) -(CH₂)_p-CO₂R₆,

g) -(CH₂)_p-CONR₇R₈,

h) -Si(R₉),

i) -(CH₂)_n-NR₇R₈,

j) -(CH₂)_n-OR₁₀,

k) -CF₃, or

l) -(CH₂)_n-SR₆, -(CH₂)_n-SOR₆, - (CH₂)_n-SO₂R₆;

R₃ is

a) OH,

b) OCH₂CH-CH₂,

c) OCH₂CH(OH)CH₂NHR₆,

d) -O-alkyl,

e) -O-(CH₂)_n-CO₂R₆, or

f) -O-(CH₂)_n-CONR₇R₈;

R₄ is

a) hydrogen,

b) halo,

c) NO₂,

d) NH₂, e) CF₃,

f) alkyl,

g) aryl,

h) -S-alkyl or aryl,

i) -SO-alkyl or aryl,

j) -SO₂-alkyl or aryl,

k) R₃, or

l) -(CH₂)_n-NR₇R₈;

Z is a primary, secondary or tertiary amine;

R₅ is a hydrogen, NO₂ , NH₂, CF₃, alkyl, aryl, -S-alkyl, -S-aryl or heteroaryl, -SO-alkyl or aryl, -S0₂-alkyl or aryl, or R₃;

R₆ is H, CF₃, alkyl or aryl, Li⁺, Na⁺, K⁺, Ca²⁺ and other pharmaceutically acceptable counter ions for carboxylic acids;

R₇ and R₈ are H, CO-alkyl, CO-aryl, alkyl, cycloalkyl, alkylaryl, aryl, heteroalkyl, aryl, or R₇ and R₈ can be taken together to form a piperidine ring or morpholine ring;

R₉ is an alkyl or aryl;

R₁₀ is H, CF₃, alkyl, aryl or heteroaryl; and

n is 0-5 and p is 0-8.

The tether or connector "β" for two of the heterocyclic groups selected from those compounds disclosed above, is chosen from one of the tether "β" structural formulae (A-E), shown on the formula sheet below; wherein

W is -CH₂-(X_n-CH₂)_n;

X is N, O or S;

R₁₁ is an alkyl, CO-alkyl or CON-alkyl or -aryl; and

m is 0-4, n is 0-5 and o is 1-5.

Examples of "alkyl" are one to 8 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl and isomeric forms thereof.

Examples of "aryl" are 6 to 12 carbon atoms such as phenyl, α- naphthyl, β-naphthyl, m-methylphenyl, p-trifluoromethylphenyl and the like. The aryl groups can also be substituted with one to 3 hydroxy,

C₁-C₃ alkoxy, C₁-C₃ alkyl, trifluoromethyl, fluoro, chloro, or bromo groups.

Examples of "cycloalkyl" are 3 to 10 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclodecyl. Examples of "alkylaryl" are alkyl chains of one to 8 carbon atoms and isomeric forms thereof which are substituted with aryl groups of 6 to 12 carbon atoms as described above.

Examples of "heteroaryl" are 6 to 12 carbon atoms aryls as described above containing heteroatoms such as nitrogen, sulfur and oxygen. Examples can include pyridine, thiophene, furan and pyrmidine.

Examples of "heteroalkyl" are one to 8 carbon atoms alkyls as described above which contain heteroatoms such as nitrogen, sulfur and oxygen.

Examples of "halo" are the halogens which include fluorine, chlorine, bromine and iodide.

Connecting two of the heterocyclic groups "α" with one of the tethers "β" produces an inhibitor of ACAT. The heterocyclic groups are bound to the tether directly by the nitrogen atoms present at each end of the tether or through from one to about 5 carbon atoms to the nitrogen atom present at the end of the tether. Generally the heterocyclic group is the same at both ends of the tether however the bivalent ligands can comprise a different heterocyclic group at either end of the tether. Regardless, tethering two heterocyclic structures together provides greater potency and those tethers containing heteroatoms appear to improve the interaction of the bivalent ligand with the tissue for inhibiting ACAT.

Various chemical schemes for preparing these compounds are described below. The specific structures for compounds prepared according to this invention are shown in Tables 1-4 along with their measured inhibition of ACAT at various levels.

The ratio of ³H-cholesteryl ester radioactivity to the sum of the ³H-cholesterol plus ³H-cholesteryl ester recovered in the cellular extracts X 100 yields the percent of total ³H-cholesterol taken up which was esterified by cellular ACAT and is referred to as percent ACAT. Percent inhibition of ACAT is also mathematically derived from the data for convenience. Values for % ACAT that are less than control values identify assay cultures in which ACAT was inhibited; the positive standard values provide a basis for relative potency evaluation. Control values for percent ACAT typically range form 60-70% under the test conditions employed.

Compound I (Table 1) is prepared by the treatment of C-7 methyl thiomethylsulfide with excess methyl iodide in methylene chloride at reflux for 72 hours to produce the allylic iodide form in a 70 to 75% yield as a pale yellow solid. This product is then treated with trimethylene-4,4-piperidine in acetonitrile in the presence of potassium carbonate to yield the allylic bisamine form, i.e., Compound I, as a powdery solid.

The synthesis of the bisaminofurobenzoxazinone, Compound II (Table I) is performed by oxidation of khellin with basic hydrogen peroxide followed by esterification of the resulting acid which affords the hydroxyester. See, U.S. Patent No. 4,412,071. Treatment of the hydroxy ester with cyanogen bromide in the presence of triethylamine (TEA) in acetonitrile yields the cyanoether. The cyanoether is then treated with trimethylene-4,4-piperidine in acetonitrile, to yield the bisaminofurobenzoxazinone, i.e., Compound II.

The synthesis of the benzodifurans, Compounds III (Table 1) (see, Example 1) is accomplished by addition of diamines to bromofurochromone or bromochromone, respectively. The addition is performed in the presence of potassium carbonate and acetonitrile.

Compounds I-III are prepared with the trimethyl-4,4-dipiperidine tether and their structure and percent ACAT inhibition in micrograms per milliliter (μg/ml) is shown in Table 1. Included in Table 1 is the single heterocyclic compound IV of Compound I which shows reduced percent ACAT inhibition and demonstrates the enhanced potency observed in the corresponding bivalent ligand Compound I.

Table 2 shows the effect of varying the tether where the heterocyclic compound is the furochromone, Compound I. The tether structure is shown with the percent ACAT inhibition for the bivalent compound. Compound I is the compound from Table 1. Table 3 shows the results of varying the groups on the bisaminofurochromone of Compound Ia.

The synthesis of the dihydrofurochromone containing Compound V (Table 3) begins with khellinone, a basic hydrolysis product of khellin. Hydrogenation of khellinone proceeds quantatively to give a product which is then subjected to claisen condensation with ethyl (α-thiomethyl) acetate followed by acid catalyzed cyclodehydration to yield dihydrofurochromone. Treatment of the dihydrofurochromone with methyl iodide and methylene chloride at reflux affords the desired allylic iodide. Treatment of the allylic iodide with dimethylene- 4,4-piperidine yields the dihydro analog, Compound V.

The trimethylsilyl analog, Compound VI (Table 3) (see Example 6) is prepared in the following manner. Treatment of timefurone with two equivalents of lithium diisopropylamide (IDA) results in the formation of a dilithio species which when treated with trimethylsilyl chloride and subjected to an aqueous workup affords the 2- trimethylsilyl analog in good yield. Treatment of this product with excess methyl iodide in methylene chloride affords the allylic iodide. Addition of dimethylene-4,4-piρeridine to the allylic iodide yields the desired bisaminofurochromone, Compound VI in 75.5% yield.

Table 4 shows bisaminobenzodifuran compounds with various substitutions and their bisaminofuran counterparts. A comparison of the percent inhibition of ACAT shows that Compound IX exhibits excellent inhibition over its monomeric counterparts. While Compound VII is active at the high dose tested (15 μg/ml), Compound IX shows surprisingly good inhibitory activity even at the 5 μg/ml dose. The data indicates that the bivalent bisaminobenzodifurans are more potent at a lower dose which shows an advantage over their monomeric counterparts (compare the 5 μg/ml dose Compound IX with the difuran analogs).

The present invention has identified classes of compounds which are structurally unique inhibitors of ACAT. The data indicates the preferred compounds are those such as Compound la (Table 2), bisaminofurochromone.

These compounds have been shown to also exhibit antiatherosclerotic activity in the SEA Japanese quail model and Netherland Dwarf rabbit. For example, five to six week old, male, SEA quails were placed on a high cholesterol diet with one group orally receiving the subject ACAT inhibitor compound la (Table 2). After eight weeks the arteries were removed, cleaned and homogenized. Total cholesterol, free cholesterol and triglycerides were measured. The results were statistically analyzed and showed a significant (thirty percent) reduction in the accumulation of esterified cholesterol in the arteries for quails that received the ACAT inhibitor compound.

In another experiment, ACAT inhibitor compound la was administered for twelve weeks at 50 mg/kg/day to Netherland dwarf rabbits that were feed a cholesterol-containing atherogenic diet. During the twelve week period serum cholesterol, triglycerides , and carnitine were monitored. At the end of the study the aortas from the drug treated group and a non-drug treated group were examined for atherosclerosis development.

There was less extensive development of hypercholesterolemia in the treated group. The mean serum cholesterol levels in the control exceeded 2200 mg/d1 whereas the mean levels in the treated group was 271 mg/dl. The lower serum cholesterol level was associated with negligible atheromatous lesion development in the treated groups. In contrast, atheromatous lesion development in the controls was extensive.

It has been concluded that the compounds of the present invention are pharmacologically effective in the reduction of esterified cholesterol not only in the general prevention or treatment of cholesterol levels but also in other physiological conditions associated with the occlusion or obstruction of arteries . For example, the subject bivalent ligands can be useful in preventing arterial occlusion in vascular trauma associated with procedures such as by-pass grafts, coronary by-passes, angioplasty and transplants.

The dosage of the bivalent ligand compound used in treatment depends on the particular use, frequency of administration and the age or condition of the recipient. Thus, the subject compounds along with any carriers or buffers would be administrated in a pharmacological amount effective to inhibit ACAT enzyme as prescribed with respect to the physiological condition diagnosed such as atherosclerosis, high blood cholesterol, artery occulsion or restriction, or surgical procedure as well as factors such as diet. Generally, the compounds can be administered in an amount of from about 0.1 to about 1000.0 mg/kg per dose.

The compounds can be administered intravenously, intramuscularly, topically, transdermally such as by skin patches, bucally or orally to man or other animals. The compositions of the present invention can be presented for administration to humans and animals in unit dosage forms, such as tablets, capsules, pills, powders, granules, sterile parenteral solutions or suspensions, oral solutions or suspensions, oil in water and water in oil emulsions containing suitable quantities of the compound, suppositories and in fluid suspensions or solutions. For oral administration, either solid or fluid unit dosage forms can be prepared. For preparing solid compositions such as tablets, the compound can be mixed with conventional ingredients such as talc, magnesium stearate, dicalcium phosphate, magnesium aluminum silicate, calcium sulfate, starch, lactose, acacia, methylcellulose, and functionally similar materials as pharmaceutical diluents or carriers. Capsules are prepared by mixing the compound with an inert pharmaceutical diluent and filling the mixture into a hard gelatin capsule of appropriate size. Soft gelatin capsules are prepared by machine encapsulation of a slurry of the compound with an acceptable vegetable oil, light liquid petrolatum or other insert oil.

Fluid unit dosage forms for oral administration such as syrups, elixirs, and suspensions can be prepared. The forms can be dissolved in an aqueous vehicle together with sugar, aromatic flavoring agents and preservatives to form a syrup. Suspensions can be prepared with an aqueous vehicle with the aid of a suspending agent such as acacia, tragacanth, methylcellulose and the like.

For parenteral administration, fluid unit dosage forms can be prepared utilizing the compound and a sterile vehicle. In preparing solutions the compound can be dissolved in water for injection and filter sterilized before filling into a suitable vial or ampoule and sealing. Adjuvants such as a local anesthetic, preservative and buffering agents can be dissolved in the vehicle. The composition can be frozen after filling into a vial and the water removed under vacuum. The dry lyophilized powder can then be sealed in the vial and reconstituted prior to use.

The following examples further demonstrate in greater detail the preparation of the bivalent ligands of the subject invention.

Example 1 2,2'-[1,3-Propanediylbis(4,1-piperidinediylmethylidy- ne)]bis[4,8-dimethoxybenzo[1,2-b;5,4-b']difuran-3(2H)- one (Compound III, Table 1)

6-Bromofurochromone (6.50 g, 20.0 mmol), trimethylene-4,4- piperidine (2.1 g, 10 mmol) and potassium carbonate (5.52 g, 40.0 mmol) are added to acetonitrile (100 ml) and heated at 60°C for 6 hours. The reaction is cooled to room temperature and diluted with water and vigorously stirred for 5-10 minutes. The solid that filled the flask is collected on a filter and air dried to yield 5.68 g (81.4%) the product as a brick red solid. An analytical sample is prepared by three recrystallizations form CHCl₃/CH₃CN and drying the compound in a heating pistol. These recrystallizations remove the red color and small amounts of a more polar impurity to yield the biligand compound in relatively pure form.

Physical characteristics are as follows:

MP: 246°C.

Anal. Calc'd for C₃₉H₄₂N₂O₁₀: C, 67.04; H, 6.01; N, 4.01. Found: C, 66.70; H, 6.13; N, 4.08.

Example 2 7,7'-[1,2-Ethanediylbis(4,1-piperidinediylmethylene)]- bis[4,9-dimethoxy-5H-furo[3,2-g] [1]-benzopyran-5-one

(Compound la, Table 2)

The allylic iodide (50 g, 129 mmol) is added to a mixture of CH₂Cl₂ (125 ml) and CH₃OH (200 ml) . To that solution is then added triethylamine (13.03 g, 129 mmol) followed by the bisamine (10.6 g, [92% pure], 49.7 mmol) in methanol (125 ml) dropwise and the resulting reaction stirred at room temperature overnight. The reaction is then diluted with methanol (2.5 1) and the resulting solid collected on a filter to give 26.2 g, 76% of analytically pure biligand compound.

Physical characteristics are as follows:

MP: 177-79°C (can be recrystallized from CH₃CN) .

Anal. Calc'd for C₄₀H₄₄N₂O2₁₀ : C, 67.40; H, 6.22; N, 3.93. Found: C, 67.21; H, 6.31; N, 3.84.

Example 3 7,7'-[1,2-Ethanediylbis(4,1-piperazinediylmethylene)]- bis[4,9-dimethoxy-5H-furo[3,2-g][1]benzopyran-5-one

(Compound lb, Table 2)

A) Preparation of Diamine tether, 1,1'-(1,2-Ethanediyl)bispip- erazine

N-Benzylpiperazine (25 g, 142 mmol), 1,2-dibromoethane (13.4 g, 71 mmol) and potassium carbonate are added to dimethylformamide (DMF)

(100 ml) and stirred at room temperature for 3 days. The reaction is diluted with water and stirred for an additional 30 minutes. The white solid that filled the flask is collected on a filter to yield, after air drying, 20 g (79.6%) of the title product as a white fluffy solid.

This product (15.0 g, 42.3 mmol) is added to a parr hydrogena¬tion bottle and dissolved in ethanol (EtOH) (50 ml). 10% palladium/-carbon (Pd/C) (10.0 g) is added and the reaction is placed under a hydrogen atmosphere (45 psi) at room temperature with shaking for 24 hours. The catalyst is removed by filtration and the ethanol removed in vacuo to leave a viscous oil. That oil is dissolved in chloroform (CHCl₃) , dried with magnesium sulfate (MgSO₄) , and the solvent removed in vacuo to yield 6.6 g (78.8%) of the desired diamine tether.

B) Preparation of Biligand Compound

Allylic iodide (772 mg, 2.0 mmol) and the diamine tether (198 mg, 1.0 mmol) are added to acetonitrile (15 ml). To that mixture is added potassium carbonate (552 mg, 4.0 mmol) and the reaction heated at reflux for 2.5 hours. The reaction is cooled to room temperature and diluted with an equal volume of water. The solid that filled the flask is collected on a filter to yield 443 mg (62.2%) of pure product. An analytical sample is prepared by recrystallization from acetonitrile.

Physical characteristics are as follows:

MP: 184-6ºC.

Analytically Calculated for C₃₈H₄₂N₄O₈: C, 63.86; H, 5.88; N, 7.84.

Found: C, 63.48; H, 5,86; N, 7.78.

Example 4 7,7'-[(2-Hydroxy-l,3-propanediyl)bis(4,l-piperazine- diylmethylene)]bis[4,9-dimethoxy-5H-furo(3,2-g)benzo- pyran-5-one (Compound Ic, Table 2)

A) Preparation of 1-[(Piperazinyl)methyl]-1-piperazineethanol tether

N-Benzylpiperazine (25 g, 142 mmol), epichlorohydrin (6.6 g, 71 mmol), sodium iodide (1.0 g) and potassium carbonate (15 g) are added to CMF (100 ml) and stirred at room temperature for 3 days. The reaction is diluted with water and stirred for an additional 30 minutes. The white solid that filled the flask is collected on a filter to afford, after air drying, 8.9 g (59.2%) of the title product as a white solid.

The amino alcohol product (14.0 g, 34.3 mmol) is added to absolute EtOH (200 ml) . 10% Pd/C (10 g) is added and the reaction hydrogenated at 50 psi for 24 hours. The catalyst is removed by filtration and the filtrate evaporated in vacuo. The resulting cloudy oil is taken up in chloroform and dried (MgSO₄). Evaporation of the solvent affords 7.02 g (89.8%) of the title product as a clear oil. This material is used without further purification. B) Preparation of Biligand Compound

The allylic iodide (5.21 g, 13.5 mmol) and diamine tether (1.54 g, 6.75 mmol) are added to acetonitrile (50 ml). To that mixture is added potassium carbonate (3.72 g, 27.0 mmol) and the reaction heated at reflux for three hours. The reaction is cooled to room temperature and diluted with an equal volume of water. The reaction is extracted with CHCl₃, dried and solvent removed in vacuo. The crude product (5 g) is chromatographed over 100 g of silica gel eluting first with CHCl₃, then 5-10% CH₃OH/CHCl₃. This affords 2.76 g (54.9%) of a light tan foam.

Physical characteristics are as follows:

Exact Mass calc'/d for C₃₉H₄₄N₄O₁₁: 745.3085. Found: 745.3078. Anal. Calc'd for C₃₉H₄₄N₄O₁₁: C, 62.90; H, 5.91; N, 7.52. Found: C, 62.27; H, 6.08; N, 7.24.

Example 5 7,7'-(4,4'Bipiperidine)-1,1'-diylbis(4,9-dimethoxy-5H- furo(3,2-g)(l)benzopyran-5-one) (Compound Id, Table 2) A mixture of allylic iodide (3.86 g, 10 mmol), amine (670 mg, 4 mmol) and triethylamine (1.01 g, 10 mmol) is stirred at room temperature in CH₃OH (10 ml) for 18 hours. The reaction is diluted with CH₃OH (250 ml), filtered and washed with CH₃OH and water. Recrystallization from CH₃OH/CH₂Cl₂ affords 1.64 g of the biligand compound.

Physical characteristics are as follows:

MP: 126-9°C.

Anal. Cal'd for C₃₈H₄₀N₂O₁₀: C, 66.66; H, 5.89; N, 4.09. Found: C, 65.96; H, 5.58; N, 4.02.

Example 6 7,7'-[1,2-Ethanediylbis(4,1-piperidinediylmethylene)]- bis-2,3-dihydro-4,9-dimethoxy-5H-furo[3.2-g][l]benzo- pyran-5-one (Compound VI, Table 3)

NaH ({50% oil dispersion}, 13.1 g, 272 mmol) is added to a 1 1 three-neck round-bottom flask. The material is thoroughly washed with hexane and the hexane replaced with THF (300 ml). 2,3-Dihydrokhellinone (19.0 g, 79.8 mmol) is dissolved in ethyl thiomethylacetate (180 ml) and the solution is added dropwise over one hour to the NaH/THF slurry. There is a slight exotherm. The reaction is stirred at room temperature for two hours at which time TLC (5% EtOAc/CH₂Cl₂) indicates that the condensation reaction is complete. The solvent is removed in vacuo and the resulting oil is diluted with an equal volume of CH₂Cl₂ and poured into CH₂Cl₂ , saturated with anhydrous HCl and stirred at room temperature for five hours. The reaction is evaporated in vacuo, washed with water and chromatographed over 800 g of silica gel. The column affords 8.2 g (33.4%) of the 4,9-dimethoxy-2,3-dihydro-[(7-methylthio)methyl]-5H-furo[3,2-b]-benzopyran-5-one as a tan solid.

The tan product (6.0 g, 19.5 mmol) is dissolved in a mixture of CH₂Cl₂/CH₃I (1/3; 20 ml) and heated at reflux for 65 hours. The reaction is evaporated in vacuo and triturated with CH₂Cl₂ (4x), discarding the solid each time (product is in the organic filtrate). The solvent is finally removed in vacuo to yield 6.25 g of 4,9-dime-thoxy-2,3-dihydro-[(7-methylthio)methyl]-5H-furo[3,2-b]-benzopyran-5-one, which is used without further purification.

To a CH₂Cl₂/CH₃OH mixture of the allylic iodide (2.5 g, 6.44 mmol) is added triethylaine (0.54 g, 5.38' mmol). The bisamine (0.53 g, 2.69 mmol [92% pure]) is then added in CH₃OH dropwise over several minutes. After stirring at room temperature overnight, the reaction is filtered and the solid washed with CH₃OH and dried to yield 0.93 g of pure product. Analytical sample is prepared from CH₃OH/CH₂Cl₂.

Physical characteristics are as follows:

MP: 204-6ºC.

Anal. Calc'd for G₄₀H₄₈N₂O₁₀: C, 67.02; H, 6.75; N, 3.91. Found: C, 66.73; H, 6.73; N, 3.88.

Example 7 2,2'[1,4-Piperazinediylbis(3,1-propanediyliminomethyl- idyne)]bis[4,8dimethoxybenzo[l,2-b;5,4-b']difuran- 3(2H)-one (Compound VIII, Table 4)

6-Bromofurochromone (6.50 g, 20.0 mmol), 1,4-bis(aminopropyl- piperazine (2.0 g, 10 mmol) and potassium carbonate (5.52 g, 40.0 mmol) are added to acetonitrile (100 ml) and heated at 60ºC for 5 hours. The reaction is cooled to room temperature and diluted with water and vigorously stirred for 5-10 minutes. The solid that filled the flask is collected on a filter and air dried to yield 6.37 g (92.6%) of the biligand as a tan solid. An analytical sample is prepared by recrystallizations from DMF (6.37 g) gives 5.6 g [81.4%].

Physical characteristics are as follows:

MP: 239°C.

Anal. Calc'd for C₃₆H₄₀N₄O₁₀: C, 62.79; H, 5.81; N, 8.13. Found: C, 62.30; H, 6.03; N, 8.21. Corrected for 0.28% water: C, 62.61; H, 5.79; N, 8.10. Example 8 2 ,2'-[1,8-Octanediylbis(iminomethylidyne)]bis[4,8-di- methoxybenzo[l,2-b;5,4-b']difuran-3(2H)-one (Compound IX, Table 4)

6-Bromofurochromone (6.50 g, 20.0 mmol), 1, 8-diaminooctane (1.44 g, 10 mmol) and potassium carbonate (5.52 g, 40.0 mmol) are added to acetonitrile (100 ml) and heated at 60°C for 5 hours. The reaction is cooled to room temperature and diluted with water and vigorously stirred for 5-10 minutes. The solid that filled the flask is collected on a filter and air dried to yield 5 . 65 g (89.4%) of the product as a brown solid. A relatively pure sample of the biligand compound is prepared by recrystallizations from CH₃CN and drying the compound in a heating pistol.

Physical characteristics are as follows:

MP: 148-50ºC.

Anal. Calc'd for C₃₄H₃₆N₂O₁₀: C, 64.55; H, 5.69; N, 4.43. Found: 64.44; H, 5.86; N, 4.46.

Example 9 7,7'-[1,2-Ethanediylbis(4,l-piperidinediylmethylene)]- bis[4,9-dimethoxy-2-(trimethylsilyl)-5H-furo[3,2g][1]- benzopyran-5-one

4,9-dimethoxy-7-methyl-2-(trimethylsilyl)-5H-furo(3,2-g)(l)ben-zopyran-5-one (5.0 g, 13.2 mmol) is dissolved in methylene chloride (20 ml) and then diluted with methyl iodide (75 g, 530 mmol). The mixture is refluxed for four days . After cooling to room temperature, the reaction is filtered and excess methyl iodide and methylene chloride removed in vacuo. This affords 4.7 g of 4,9-dimethoxy-2-trimethylsilyl-7-iodomethyl-5H-furo[3,2-b]-benzopyran-5-one of sufficient purity for use in the next step.

The allylic iodide is dissolved in a mixture of CH₂Cl₂ and CH₃OH (10/15 ml). To that solution is added the bisamine in CH₃OH (5 ml) and the reaction is stirred at room temperature overnight. The reaction is evaporated in vacuo and the resulting solid is slurried with cold CH₃OH and filtered to afford 1.70 g (75.5%) of the biligand compound. An analytical sample is prepared by recrystallization from CH₃OH/CH₂Cl₂.

Physical characteristics are as follows:

MP: 84-7°C.

Anal. Calc'd for C₄₆H₆₀N₂O₁₀Si₂: C, 64.46; H, 7.06; N, 3.27. Found: C, 64.07; H, 6.98; N, 3.31. TABLE 1

Trimethylene-4,4-dipiperidine Tether

Compound

₃ %

*Not a bivalent ligand of the su TABLE 2

Variation of the Amine Tether in the Furochromone System

Compound Amine Tether % ACAT Inhibition IC₅₀

(μg/ml)

TABLE 3

Modifications of the Furochromone Nucleus with the 1,2-Ethanediyl- (4,4-dipiρeridine) Tether

Compound

Compound % ACAT Inhibition IC50

(μg/ml)

*Not compounds of the subject invention. HETEROCYCLIC COMPOUNDS "α"

TETHERS "β"

B) -NR₁₁-W-NR₁₁

Claims (10)

1. A compound comprising: a bivalent ligand α-β-α wherein α is structurally represented by the formula

wherein:

X and Y are independently O, N or S;

A is C=CH-Z, N=C-Z or CR₅=C- (CH₂)_n-Z;

R₁ and R₂ are independently:

a) H,

b) halo,

c) alkyl,

d) -(CH₂)_p-aryl,

e) -(CH₂)_p-heteroaryl,

f) -(CH₂)_p-CO₂R₆,

g) -(CH₂)_p-CONR₇R₈,

h) -Si(R₉),

i) -(CH₂)_n-NR₇R₈,

j) -(CH₂)_n-OR₁₀,

k) -CF ₃- or

1) -(CH₂)_n-SR₆, -(CH₂)_n-SOR₆, -(CH₂)_n-SO₂R₆;

R₃ is

OH,

OCH₂CH=CH₂,

OCH₂CH(OH)CH₂NHR₆,

-O-alkyl,

-O-(CH₂)_n-CO₂R₆, or

-O-(CH₂)_n-CONR₇R₈;

R₄ is

a) hydrogen,

b) halo,

c) NO₂, d) NH₂ ,

e) CF₃ ,

f) alkyl,

g) aryl ,

h) -S-alkyl or aryl,

i) -SO-alkyl or aryl,

j) -SO₂-alkyl or aryl,

k) R₃, or

1) -(CH₂)_n-NR₇R₈;

Z is a primary, secondary or tertiary amine;

R₅ is a hydrogen, NO₂, NH₂, CF₃, alkyl, aryl, -S-alkyl, -S-aryl or heteroaryl, -SO-alkyl or aryl, -S0₂-alkyl or aryl, or R₃;

R₆ is H, CF₃, alkyl or aryl, Li⁺, Na⁺, K^4", Ca²⁺ and other pharmaceutically acceptable counter ions for carboxylic acids;

R₇ and R₈ are H, CO-alkyl, CO-aryl, alkyl, cycloalkyl, alkylaryl, aryl, heteroalkyl, aryl, or R₇ and R₈ can be taken together to form a piperidine ring or morpholine ring;

R₉ is an alkyl or aryl;

R₁₀ is H, CF₃, alkyl, aryl or heteroaryl; and

n is 0-5 and p is 0-8; and

β is selected from the group consisting of: A)

B) -NHR₁₁-W-NHR₁₁

C)

D)

E)

wherein:

W is -CH₂-(X_n-CH₂)_n;

X is N, O or S; R₁₁ is an alkyl, CO-alkyl or CON-alkyl or -aryl; and m is 0-4, n is 0-5 and o is 1-5.

2. The compound of claim 1 wherein said tether is:

a) trimethylene-4,4-dipiperidine,

b) 1,2-ethanediyl-4,4-dipiperidine,

c) 1,4-bis(aminopropylpiperazine), or

d) 1,8-diaminooctane.

3. The compound of claim 1 which is 7,7'-[1,2-ethanediylbis(4,1-piperidinediylmethylene)]-bis[4,9-dimethoxy-5H-furo[3,2-g][1]-benzopyran-5-one.

4. A method for blocking or inhibiting ACAT enzyme comprising: administering a pharmacological amount of a composition of claim 1.

5. The method of claim 4 wherein said administration is made subsequent to by-pass surgery, coronary by-pass surgery, angioplasty or transplants.

6. The method of claim 4 wherein said tether is:

a) trimethylene-4,4-dipiperidine,

b) 1,2-ethanediyl-4,4-dipiperidine,

c) 1,4-bis(aminopropylpiperazine), or

d) 1,8-diaminooctane.

7. The method of claim 4 wherein said composition is 7,7'-[1,2-ethanediylbis(4,1-piperidinediylmethylene)]-bis[4,9-dimethoxy-5H-furo[3,2-g][1]-benzopyran-5-one.

8. A method for preventing or treating atherioscelrosis comprising: administering a pharmacological amount of a composition of claim 1.

9. The method of claim 8 wherein said tether is:

a) trimethylene-4,4-dipiperidine,

b) 1,2-ethanediyl-4,4-dipiperidine,

c) 1,4-bis(aminopropylpiperazine), or

d) 1,8-diaminooctane.

10. The method of claim 8 wherein said composition is 7, 7'-[1,2-ethanediylbis(4,1-piperidinediylmethylene)]-bis[4,9-dimethoxy-5H-furo[3,2-g][1]-benzopyran-5-one.