WO1995003803A1 - SUBSTITUTED FURO[3',4':6,7]INDOLIZINO[1,2-b]QUINOLINONES - Google Patents

Abstract

The present invention provides a method of treating viral infections by using antiviral substituted furoindolizino[1,2-b]quinolinone compounds, antiviral substituted furoindolizino[1,2-b]quinolinone compounds, and pharmaceutical compositions thereof.

Description

SUBSTITUTED FURO[3',4':6,7]INDOLIZINO[ 1 ,2-b]QUINOLINONES

This application is a continuation-in-part of International Application No. PCT/US93/01027 of Berges, et al., having an International filing date of 05 February 1993, which International Application claims priority from U.S. Serial No. 07/839,823 of Berges, et al., filed on February 21, 1992, now abandoned.

SCOPE OF THE INVENTION This invention relates to antiviral compounds, pharmaceutical compositions thereof, and a method of treating viral infections. More specifically, this invention relates to certain furoindolizino[l,2-ft]quinolinyl derivatives which have antiviral activity.

BACKGROUND OF THE INVENTION Certain lH-pyrano[3',4':6,7]indolizino[l,2-b]quinolinones are known to have cytotoxic and antiviral activity. Camptothecin is an example of one such compound. It is a water-insoluble, cytotoxic alkaloid produced by Camptotheca acuminata trees indigenous to China and Nothapodytes foetida trees indigenous to India. Camptothecin and a few close congeners are known to inhibit eukaryotic topoisomerase I. The cytotoxic and antitumor activity of camptothecin and its close congeners is due to inhibition of eukaryotic topoisomerase I {Cancer Res. 1988, 48, 1722; Molec. Pharmacol. 1988, 34, 755.) Compounds that are related in structure to camptothecin but do not inhibit eukaryotic topoisomerase I are not cytotoxic to mammalian cells and have no antitumor activity (J. Med. Chem. 1988, 32, 715; Cancer Res. 1989, 49, 1465; Cancer Res. 1989, 49, 4358).

Camptothecin has been shown to have an effect on viruses by a number of investigators in laboratory settings. Although camptothecin has demonstrated antiviral activity in in vitro tissue culture systems, camptothecin and its close analogs that have an E-ring hydroxylactone moiety cannot be considered as useful in vivo antiviral agents because they inhibit mammalian topoisomerase I, inhibit host cell DNA replication, and are cytotoxic to mammalian cells. Furthermore, camptothecin is not expected to be attractive for drug development as an antiviral agent because of unacceptable dose-limiting toxicity, unpredictable toxicity, poor aqueous solubility, and/or unacceptable shelf life stability. There is a need for new antiviral agents. Substituted indolizino[l ,2- fc]quinolinones that lack the E-ring α-hydroxy lactone moiety of camptothecin have been shown to be non-cytotoxic to mammalian cells and to lack antitumor activity (Ann. Rev. Pharmcol. Toxicol. 1977, 17, 117; J. Med. Chem. 1989, 32, 715). This is because these compounds do not contain the essential structural features required to inhibit eukaryotic topoisomerase I. But it has been found that some substituted furo[3',4':6,7]indolizino[l,2-fr]quinolinones lacking the E-ring hydroxylactone moiety do have antiviral activity without the undesirable features of camptothecin. As such they are useful for treating viral infections.

SI JMM ARY OF THE INVENTION

In a first aspect, the present invention provides a method for treating viral infections, which method comprises administering to an infected host in need thereof an effective amount of a compound of Formula I, or a pharmaceutically acceptable salt thereof, alone or in combination with a carrier, diluent or excipient

wherein:

R⁷ is -H, -CN, lower alkyl or -(CH2)_nCH2V where n=0-3;

R⁹ is -H, -OR, -NRR¹, -CN, -(CH2)_nCH2V where n=0-3;

RΪO is -H, -OR, -OCH2OCH2CH2OCH3, -NRR¹, -CN, -COR¹², -CH(OH)Rl2, - 0-(CH2)l-5CH2NRR¹, -OCCOJNRR¹, l,4'-bipiperidine-l'-carboxy, -(CH2)_nCH2V where n=0-3;

V is -OH, -OCOR¹⁴, OPCOXOHJRΪS or -NRR¹;

Rⁿ is -H or -OR;

R¹² is -H or lower alkyl; R¹^ is lower alkyl;

R and R¹ are independently selected from the group consisting of -H, -Ci-6 alkyl, and, when R and R¹ are substituted on nitrogen, R and R¹ can be taken together to form a 5-7 membered saturated heterocyclic ring containing the nitrogen;

R¹⁴ is -CR¹²R¹⁶R¹⁷;

-(CH₂)_nCH2R¹⁷ (where n=l-3);

(where n=0 or 1, and CH2R¹⁷ can be substituted on the phenyl at the 2, 3, or 4 position);

-O(CH₂)_nCH₂R¹⁷ (where n = 1-3);

-NRR¹;

-NH(CH₂)_nCH2R¹⁷ (where n = 1-3);

R^Ϊ5 is OH, OR¹⁸ or CH₂NH₂;

R¹6 is H or the side chain of any naturally occuring α-amino acid;

where X is any pharmaceutically acceptable anion; R ⁸ is lower alkyl;

Q is CR²R¹² and T is CH₂ or C=O, or

Q is CR and T is CH;

the dotted lines represent a double bond between carbons 3a and 13a, a single bond between carbons 1 and 13a, and a single bond between carbons 3 and 3a when Q is CR²R¹² and T is CH₂ or C=O;

the dotted lines represent a single bond between carbons 3a and 13a, a double bond between carbons 1 and 13a, and a double bond between carbons 3 and 3a, when Q is CR and T is CH;

R² is -H, -OR, or -OC(O)R;

provided that: if one of R⁷, R⁹ , R¹⁰ or R¹¹ is other than -H, only one of the others may be other than -H; and only one of R⁹ or R¹⁰ may be -NRR¹.

In another aspect, this invention relates to certain novel compounds of Formula II, or a pharmaceutically acceptable salt thereof

π wherein:

the substituents are the same as defined for Formula I, except that:

Q is CR²R¹²; and T is CH₂ or C=O;

provided that:

if one of R⁷, R⁹ , R¹⁰ or R¹¹ is other than -H, only one of the others may be other than -H;

only one of R⁹ or R¹⁰ may be -NRR¹;

R⁷, R⁹, R¹⁰, and R¹¹ are not all -H when T is C=O and Q is C(H)(CH₂CH₃); and

R⁷, R⁹, R¹⁰ and R¹¹ are not all -H when T is CH₂ and Q is C(OH)(CH₂CH3).

In yet another aspect, the present invention provides novel compounds of

Formula m, or a pharmaceutically acceptable salt thereof

III

wherein:

the substituents are the same as defined for Formula I,

provided that:

if one of R⁷, R⁹ , R¹⁰ or R¹¹ is other than -H, only one of the others may be other than -H; and

only one of R⁹ or R¹⁰ may be -NRR¹. Another aspect of the present invention also provides a composition comprising a compound of either Formula II or III in combination with an acceptable carrier, excipient, or diluent, particularly a pharmaceutically acceptable carrier, excipient, or diluent.

DETAILED DESCRIPTION OF THE INVENTION

The terms below, defined as follows, are used in describing the present invention throughout this application. "Aliphatic" is intended to include saturated and unsaturated radicals. This includes normal and branched chains, saturated or mono- or poly- unsaturated chains where both double and triple bonds may be present in any combination. The phrase "lower alkyl" refers to an alkyl group of 1 to 6 carbon atoms in any isomeric form, particularly the normal or linear form. "Lower alkoxy" means the group lower alkyl-O-. "Halo" means fluoro, chloro, bromo or iodo. "Acyl" means the radical having a terminal carbonyl carbon.

The term "5-7 membered saturated heterocyclic ring containing the nitrogen" is intended to include saturated rings such as piperidine, pyrrolidine, morpholine, piperazine, and N-alkyl piperazine. The term " 1 ,4'-bipiperidine- 1 '-carboxy " is used to identify the following radical:

Salts of any sort may be made from the present compounds, provided there is an acidic group present or a sufficiently basic nitrogen. Particularly preferred are the pharmaceutically acceptable salts of the instant compounds. These latter salts are those which are acceptable in their application to a pharmaceutical use. By that it is meant that the salt will retain the biological activity of the parent compound and the salt will not have untoward or deleterious effects in its application and use in treating diseases.

Pharmaceutically acceptable salts are prepared in a standard manner. The parent compound in a suitable solvent is reacted with an excess of an organic or inorganic acid, in the case of acid addition salts of a base moiety, or an excess of organic or inorganic base in the case where there is an acid group. Representative acids are hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, acetic acid, maleic acid, succinic acid or methanesulfonic acid. Cationic salts are readily prepared from metal bases such as sodium, potassium, calcium, magnesium, zinc, copper or the like and ammonia. Organic bases include the mono or disubstituted amines, ethylenediamine, piperazine, amino acids, caffeine, and the like.

Here and throughout this application, the compounds of the present invention are numbered according to structural formula IV:

If a chiral center or some other form of an isomeric center is created by some combination of substituents in a compound of the present invention, all forms of such isomer(s) are intended to be covered herein. Inventive compounds containing a chiral center may be used as a racemic mixture or the mixture may be separated and an individual enantiomer may be used alone.

The present invention provides a method for the treatment of viral infections comprising administering to an infected animal, particularly a mammal, most particularly a human, in need thereof an effective amount of a compound of Formula I as described hereinabove, or a pharmaceutically acceptable salt thereof, alone or in combination with a carrier, excipient or diluent. The term "an effective amount" is herein defined as that amount of a compound of the present invention which provides a desirable and well-known therapeutic end-point, e.g. control, remission or cure of viral infection as would be recognized by one of ordinary skill in the art of treating viral infections.

The present invention also provides compounds, and pharmaceutically acceptable salts thereof, which exhibit antiviral activity, said compounds having the structure represented by either Formula II or III, as described hereinabove.

The present method is useful for treating viral infections in animals caused by a broad variety of DNA replicating animal viruses. The present method is particularly useful in treating viral infections caused by herpes simplex virus, particularly herpes simplex virus type 1 (HSV1) and herpes simplex virus type 2 (HS V2), varicella zoster virus (VZV), or cytomegalovirus (CMV) when the infected host is a mammal, particularly when the infected host is human.

No unacceptable toxicological effects are expected when compounds of the present invention are administered in accordance with the present invention. A preferred method of treating viral infections according to the present invention uses compounds of Formula I where T is CH₂, Q is C(OR)(Cι_6alkyl), R⁷ is -H, R⁹ is -H, R¹¹ is -H, and R¹⁰ is -H, -OR, or -OCH₂OCH₂CH₂OCH₃. Another preferred method of treating viral infections according to the present invention uses compounds of Formula I where T is C=O, Q is C(H)(Ci-6alkyl), and R⁷, R⁹, R¹⁰, and R¹¹ are all -H.

Yet another preferred method of treating viral infections according to the present invention uses compounds of Formula I where T is CH, Q is CR, where R is Ci-βalkyl, and R⁷, R⁹, R¹⁰, and R¹¹ are all -H.

Preferred compounds of the present invention include those of Formula II where T is CH₂, Q is C(OR)(Cι^alkyl), R⁷, R⁹, R¹¹ are -H, and R¹⁰ is -H, -OR, or -OCH₂OCH₂CH₂OCH3_, provided that Q is not C(OH)(CH₂CH₃) when R^ is -H. Another group of preferred compounds are those of Formula II where T is

C=O, Q is C(H)(Cι^alkyl), provided that Q is not C(H)(CH₂CH3), and R⁷, R⁹, R™, and R¹¹ are all -H.

Yet another group of preferred compounds are those of Formula III where R is -Ci-βalkyl, and R⁷, R⁹, R¹⁰, and R¹¹ are all -H. The most preferred compounds of the present invention are:

3-ethyl- 1,11 -dihydro-3-methoxy-3H, 13H-furo[3'4':6,7]indolizino[ 1 ,2-b]quinolin- 13-one;

3-ethyl- 11H, 13H-furo[3',4':6,7]indolizino[ 1 ,2-fc]quinolin- 13-one; and

3-ethyl- 1 , 1 l-dihydro-3-hydroxy-8-[(2-methoxyethoxy)methoxy]-3H, 13H-furo[3',4': 6,7]indolizono[ 1 ,2-fc]quinolin- 13-one.

The most preferred compounds for use in the method of the present invention include the above-named most preferred inventive compounds as well as the following known compounds:

3-ethyl- lH,3H-furo[3',4':6,7]indolizino[ 1 ,2-b]quinolin- 1,13(1 lH)-dione; and

3-ethyl- 1,11 -dihydro-3-hydroxy-3H, 13H-furo[3',4': 6,7]-indolizino[ 1 ,2-b]quinolin- 13-one.

Some compounds used in the present method are known. Here and throughout this application, published references describing how to make these known compounds are incorporated herein by reference. The compounds of the present invention can be prepared by several preferred synthetic methods, as discussed below. Compounds of the present invention having desired A B ring substitutents can be prepared by introducing the substitutents onto the camptothecin starting material either prior to or after formation of the furan ring. In particular, compounds of the present invention having the desired ring substituents may be conveniently prepared from 4-ethyl-3,4-dihydroxy-lH-pyrano- [3',4':6,7]indolizino[l,2-b]quinolin-14(4H,12H)-ones. As illustrated in Scheme 1, these intermediates may be conveniently prepared by reduction of the carbonyl group of the lactone ring of appropriately substituted camptothecins, which are themselves prepared by well-known method.

Scheme 1

Substituted camptothecins may be prepared from camptothecin, 9- hydroxycamptothecin, or 10-hydroxycamptothecin (4-ethyl-4,9-dihydroxy-lH- pyrano[3',4':6,7]indolizino[l,2-fe]quinoline 3,14(4H,12H)-dione) by applying the methods described in published International Application No. WO 92/07856, published on May 14, 1992. Starting materials are commercially available or can be made by published methods. Camptothecin, 10-hydroxy camptothecin and 9- hydroxycamptothecin are natural products. Camptothecin and 10- hydroxycamptothecin are publicly available from sources in the People's Republic of China. A 9-hydroxycamptothecin compound which can be used as starting material for making some of the inventive compounds is described in published Japanese Patent Application No. 59-51289. A total synthesis of camptothecin is described in Wall, et al., J. Med. Chem., 1980, 23, 554. The 1980 Wall synthesis is useful for introducing one or more R⁷-R^π substituents into precursors of the compounds of Formula I. To do so, the Wall synthesis is modified, using well- known methods, at the appropriate step to provide for insertion of the desired substituent. The camptothecins used as starting materials can be either the pure natural enantiomer or a mixture of enantiomers.

It will be readily understood by those skilled in the art that in order to prepare some of the compounds of the present invention it is necessary to protect certain ring substituents from reduction during the lactone reduction and from the oxidizing agent or base used in the formation of the fiiran ring. For instance, where R¹^ = COR¹² and R¹² is not H, the lactone reduction is preferably carried out on the vinyl ether derivative (R¹⁰ = C(OR¹⁸)CHR¹²) of the ketone group. The vinyl ether is then cleaved by mild acid treatment to give the ketone. When R¹^ = COR¹² and R¹² is H, carbonyl group is preferably protected as a dithioacetal during the reduction step. The acetal is then cleaved to give the aldehyde.

In general, the furan ring may be formed by a process comprising: i) treating a lH-pyrano-[3',4':6,7]indolizino[l,2-b]quinolin-14(4H,12H)-one with an oxidizing agent to form an 8-formyloxymethyl-7-(l-oxopropylindolzino[l,2-b]quinolin- 9(1 lH)-one; and ii), forming a ring by treating the quinolin-9(l lH)-one with base, for example potassium carbonate.

The 3-hydroxy group of the furan ring can be derivatized. In particular, protection of this group with an ether derivative allows the introduction of other substitutents onto the quinoline portion of the molecule. As shown in reaction Scheme 2, the preparative process involves first treating the corresponding 4-ethyl-3,4-dihydroxy-lH-pyrano[3',4':6,7] indolizino[l,2-b]quinolin-14(4H,12H)-ones with an oxidizing agent such as sodium metaperiodate to form an 8-formyloxymethyl-7-(l-oxopropyl)indolizino [1,2- fc]quinoline-9(HH)-one from which the formyl group is then cleaved, for example by mild base treatment, resulting in a hydroxy ketone which then spontaneously cyclizes to a 3-ethyl- 1, l l-dihydro-3-hydroxy- 3H, 13H- furo[3',4':6,7]indolizino[l,2-fc]quinolin-13-one. The hydroxy group of these compounds can be replaced with an ether moiety by treating the hydroxy compound with an alcohol with acid catalysis. Alternatively, the hydroxy compound can be dehydrated, for example with trifluoroacetic acid, to give the corresponding 3-ethyl- 11H, 13H-furo[3',4':6,7]indolizino[ 1 ,2-b]quinolin- 13-one. Scheme 2

The assay used to test the compounds of the present invention for antiviral activity is well-known. A generalized description of the assay follows.

Well plates are seeded with the appropriate cells at a concentration of lxlO⁵ cells per well suspended in 0.5 mL of Earle's Minimum Essential Medium (EMEM) containing 10% fetal bovine serum (FBS) and antibiotic and antimycotic solution. After the cells are 80-90% confluent (24 hours), old medium is removed and washed with Hank's buffered saline solution (HBSS). Cells are then infected for 1 hour at 37°C with 100-200 plaque forming units per well of a herpes simplex virus suspended in 250 mL HBSS. Following adsorption, the following are added:

A) 250 mL well 2 x EMEM containing Human IgG (Sigma Chemical Co., St. Louis, Mo.) (ca. 0.1 mg/mL); B) 250 mL/well EMEM containing 10% FBS and antibiotic/antimycotic solution; and

C) 250 mL well HBSS containing appropriately diluted compound.

After 24-48 hours (best time determined by observation of plaques under a microscope), old medium is aspirated off. Each well is stained with a selected stain solution (0.5% crystal violet in MeOH:H₂O 7:3) and then rinsed with water, air dried, and the plaques are counted. Compound effectiveness is evaluated in terms of percent plaque reduction as compared to untreated, infected controls. This assay can be used to test compound activity against many other viruses besides herpes simplex by simply modifying the cell type used in the first step to match the virus being tested, and otherwise following the procedure outlined above. Other cell types which can be used in this assay include mouse mammary tumor cells, human lung fibroblasts, sheep chorioplexus cells, and green monkey kidney cells.

Alternatively, other assays can be used to determine the antiviral activity of the present compounds. Such assays include the following types: cell count, clonogenic, cytopathic effect, dish-colony formation, microtiter-growth inhibition, thymidine incorporation and yield reduction. Each of these assays is well-known and is available either from the literature or from a commercial testing lab.

The present invention provides pharmaceutical compositions prepared from the compounds of Formula I. These compositions have both a human and veterinary utility, and comprise an excipient or carrier which is acceptable for the intended pharmaceutical end use and at least one inventive compound. For example, if a veterinary use is intended, the carrier may be a liquid, or spray, or may be formulated in a solid, non-degradeable or degradeable form for insertion in the rumen. Selected excipients and carriers may be employed to prepare compositions acceptable or adaptable for human use.

An effective amount of the pharmaceutical compositions of the present invention may be contained in one embodiment, such as in a single pill, capsule, or pre-measured intravenous dose or pre-filled syringe for injection. Alternatively, as is frequently the case, the composition will be prepared in individual dose forms where one unit, such as a pill, will contain a sub-optimal dose but the user will be instructed to take two or more unit doses per treatment. When the composition is presented as a cream, it will contain a discrete amount of drug and the user will apply some amount of the cream one or more times until the disease is in remission or has been effectively treated. Concentrates for later dilution by the end user may also be prepared, for instance for IV formulations and multi-dose injectable formulations.

Carriers or diluents contemplated for use in these compositions are generally known in the pharmaceutical formulary arts. Reference to useful materials can be found in well known compilations such as Remington's Pharmaceutical Sciences. Mack Publishing Co., Easton, Pa.

The nature of the composition and the pharmaceutical carrier or diluent will, of course, depend upon the intended route of administration, for example whether by intravenous and intramuscular injection, parenterally, topically, orally, or by inhalation.

For parenteral administration the pharmaceutical composition will be in the form of a sterile injectable liquid such as an ampule or an aqueous or nonaqueous liquid suspension.

For topical administration the pharmaceutical composition will be in the form of a cream, ointment, liniment, lotion, paste, spray or drops suitable for administration to the skin, eye, ear, nose or genitalia.

For oral administration the pharmaceutical composition will be in the form of a tablet, capsule, powder, pellet, atroche, lozenge, syrup, liquid, or emulsion.

The pharmaceutical carrier employed may be, for example, either a solid or liquid. When the pharmaceutical composition is employed in the form of a solution or suspension, examples of appropriate pharmaceutical carriers or diluents include: for aqueous systems, water, for non-aqueous systems: ethanol, glycerin, propylene glycol, olive oil, corn oil, cottonseed oil, peanut oil, sesame oil, liquid paraffins, and mixtures thereof with water; for solid systems: lactose, terra alba, sucrose, talc, gelatin, agar, pectin, acacia, magnesium stearate, stearic acid, kaolin and mannitol; and for aerosol systems: dichlorodifluoromethane, chlorotrifluoroethane and compressed carbon dioxide. Also, in addition to the pharmaceutical carrier or diluent, the instant compositions may include other ingredients such as stabilizers, antioxidants, preservatives, lubricants, suspending agents, viscosity modifiers and the like, provided that the additional ingredients do not have a detrimental effect on the therapeutic action of the instant compositions. Similarly, the carrier or diluent may include time delay material well known to the art, such as glyceryl monostearate or glyceryl distearate alone or with a wax, ethylcellulose, hydroxypropylmethylcellulose, methylmethacrylate and the like. A wide variety of pharmaceutical forms can be employed. Thus, if a solid carrier is used, the preparation can be tableted, placed in a hard gelatin capsule in powder or pellet form or in the form of a troche or lozenge. The amount of solid carrier will vary widely but preferably will be from about 25 mg to about 1 gram. If a liquid carrier is used, the preparation will be in the form of a syrup, emulsion, soft gelatin capsule, sterile injectable solution or suspension in an ampule or vial or nonaqueous liquid suspension. To obtain a stable, water-soluble dose form, a pharmaceutically acceptable salt of the compound of Formula I is dissolved in an aqueous solution of an organic or inorganic acid or base. If a soluble salt form is not available, the compound of Formula I may be dissolved in a suitable co-solvent or combinations thereof. Examples of such suitable cosolvents include, but are not limited to, alcohol, propylene glycol, polyethylene glycol 300, polysorbate 80, glycerin and the like in concentrations ranging from 0-60% of the total volume. It will be appreciated that the actual preferred dosages of the compounds used in the compositions of this invention will vary according to the particular complex being used, the particular composition formulated, the mode of administration and the particular site, host and disease being treated. It is expected that these compounds will be active in the concentration ranges of two commercial antiviral drugs, Cytovene (ganciclovir) and Zovirax (acyclovir). The latter is manufactured in 200 mg capsules with instructions for treating herpes simplex viral infections by taking one capsule every 4 hours, but not to exceed 5 capsules per day. In the following Examples, temperature is given in degrees Centigrade (°C).

Unless otherwise indicated, all of the starting materials were obtained from commercial sources. Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. These Examples are only given to illustrate the invention, not to limit its scope. Reference is made to the claims for what is reserved to the inventors hereunder.

EXAMPLES

E am le l r+ 3-F.thyl-l .1 l-dihvdro-3-hvdroxy-3H.13H-furor3'.4':6.71-indoIizinoπ .2- frlφιinolin-13-one.

1A. 8-Formyloxymethvl-7-(l-oxθDropvnindolizinoπ.2-blαuinolin-9rn -one.

To a suspension of (4S,3R,S)-ethyl-3,4-dihydroxy-lH-pyrano- [3',4':6,7]indolizino[l,2-fc]quinolin-14(4Η,12Η)-one (1.04 g, 3.0 mmol) (prepared by the method of T. R. Govindachari, K. R. Ravindranath, and N. J. Viswanathan J. Chem. Soc, Perkin Trans.,1974, 1215) in glacial acetic acid (70 mL) was added dropwise a solution of sodium metaperiodate (1.0 g, 4.7 mmol) in H2O (20 mL). The resulting mixture was stirred at room temperature for 30 min, at which time ethylene glycol (1 mL) was added. Water (350 mL) was slowly added, and the mixture was cooled to 0°C. The precipitate which formed was collected by filtration and recrystallized from acetone/H2θ to provide yellow needles of the title compound as a hydrate, mp >200°C (dec). ^lH NMR (CDCl3/DMSO-d6) d 8.43 (br s, 1H), 8.20-7.40 (m, 5H), 7.23 (s, 1H), 5.28 (br s, 4H), 2.95 (q obscured by HOD peak, 2H), 1.18 (t, 7 = 6 Hz, 3H). Anal. Calcd for C20H16N2O4Η2O: C, 65.57; H, 4.95; N, 7.65. Found: C, 65.53; H, 4.84; N, 7.33.

IB. f±V3-Ethyl-l .1 l-dihvdro-3-hvdroxy-3H.13H-furor3'.4':6.7Ηndo1i7inoπ 9- frlquinolin-1 -one.

To a mixture of 8-formyloxymethyl-7-(l-oxopropyl)-indolizino[l,2-b]- quinolin-9(HH)-one (1.05 g, 2.9 mmol) in 1:1 methanol/acetone (500 mL) under an argon atmosphere was slowly added a solution of K₂CO3 (300 mg, 2.2 mmol) in Η₂O (10 mL). The resulting orange solution was stirred at room temperature for 30 min and concentrated under reduced pressure. Water was added to the residue, and the pH was adjusted to 4 with glacial acetic acid. The mixture was stirred at room temperature overnight and filtered. The solid obtainedwas washed with H₂O and purified by flash chromatography on silica gel, eluting with 3% MeOH/CHCl3. Crystals of the product as a hydrate formed in the eluate, mp 219-221 °C (dec). ^!H NMR (MeOH-d₄, referenced to CD₂HOD peak at d 3.35) d 8.42 (s, 1H), 8.12 (d, / = 8.2 Hz, 1H), 7.92 (br d, J = 7.0, 1H), 7.79 (m, 1H), 7.63 (m, 1H), 7.40 (s, 1H), 5.25 (s, 2H), 5.14 (d, J = 14.2 Hz, 1H), 4.97 (d, J = 14.1 Hz, 1H), 2.09 (2 overlapping q, J = 7.2 Hz, 2H), 0.86 (t, / = 7.4 Hz, 3H). Anal. Calcd for

C1₉H₁6N2O3 I 1/4 H₂O: C, 66.56; H, 5.44; N, 8.17. Found: C, 66.52; H, 5.49; N, 7.78. Example 2 rJ:V3-Ethyl-l.l l-dihvdro-3-methoxy-3H.13H-furor3'4':6.71indolizinoπ.2- frlφιinolin-13-one. A mixture of 3-ethyl-l,l l-dihydro-3-hydroxy-3H,13H- furo[3',4':6,7]indolizino-[l,2-b]quinolin-13-one (10.5 mg, 33 mmol) and Dowex AG50W-X8 (Η⁺) ion exchange resin (11 mg) in dry MeOH (3 mL) was stirred at room temperature for 1.5 h, and then the mixture was allowed to stand at 0°C overnight. The suspension was decanted from the resin beads, and the solid which formed was collected by filtration and dried to provide the title compound as a crystalline solid. -1H NMR (CDCI3) d 8.40 (s, 1H), 8.20 (d, 1H), 7.92 (d, 1H), 7.82 (m, 1H), 7.65 (m, 1H), 7.27 (s, 1H), 5.33 (s, 2H), 5.18 (2d, 2H), 3.15 (s, 3H), 2.06 (m, 2H), 0.87 (t, 3H).

Example 3 r±V 3-Ethyl- 1.11 -dihvdro-3-hvdroxv-8-rf2-methoxvethoxv')methoxyl-3H.13/7- furor3'.4': 6.71indolizonoπ.2-frlαuinolin-13-one.

3A. rSV4-Ethyl-4-hvdroxy-9-rf2-methoxyethoxy.methoxy1-lH-nyrano-r3'.4': 6.71indolizinoπ.2-frlquinoIine-3.14 (4H. 12H)-dione.

To a solution of (S)-4-ethyl-4,9-dihydroxy-lH-pyrano-[3',4':6,7]- indolizino[l,2-&]quinoline-3,14(4H,12H)-dione (also known as 10- hydroxycamptothecin, 1.08 g, 3.0 mmol) in DMF (20 mL) at 0°C under an argon atmosphere was added sodium hydride (130 mg of 60% suspension in mineral oil, 3.3 mmol). After stirring for 1 h at 0°C, methoxyethoxymethyl chloride (0.40 g, 3.3 mmol) was added dropwise. The reaction mixture was allowed to warm to room temperature and stirred overnight. Thin layer chromatographic analysis indicated that the reaction was incomplete, and the mixture was recooled to 0°C and additional sodium hydride (33 mg of 60% suspension in mineral oil, 0.8 mmol) was added. After stirring 20 min at 0°C, methoxyethoxymethyl chloride (95 mL, 0.8 mmol) was added. The reaction mixture was allowed to warm to room temperature and stirred overnight. The solvent was removed in vacua, and Η2O was added to the residue, which was then extracted with CH2CI2 (3x). The combined organic extracts were dried (Na2SO4), and the solvent was removed in vacuo. The residue was purified by flash chromatography on silica gel, eluting with a solvent gradient from 2-4% EtOH/EtOAc. The light yellow crystals obtained were recrystallized from MeOH to give the title compound as a hydrate. -1H NMR (DMSO-d6) d 8.55 (s, IH), 8.10 (d, J = 8.8 Hz, IH), 7.63 (s, IH), 7.56 (obscured dd, J = 2.9 Hz, IH), 7.29 (s, IH), 6.48 (br s, IH), 5.45 (s, 2H), 5.41 (s, 2H), 5.26 (br s, 2H), 3.78 (m, 2H), 3.48 (m, 2H), 3.22 (s, 3H), 1.87 (q, J = 7.5 Hz, 2H), 0.88 (t, J = 7.7 Hz, 3H). Anal. Calcd for C24H24N2O7-1/8 H2O: C, 63.39; H, 5.38; N, 6.16. Found: C, 63.26; H, 5.64; N, 6.43.

3B. r4S.3R.SV4-Ethvl-3.4-dihvdroxv-9-r(2-methoxvethoxv')methoxv1-17/- pyrano-r3'.4': 6.71indolizinori.2-felQuinolin-14(4H.12H>-one. To a solution of (S)-4-ethyl-4-hydroxy-9-[(2-methoxyethoxy)methoxy]-lH- pyrano-[3',4': 6,7]indolizino[l,2-fc]quinoline-3,14 (4H, 12H)-dione (200 mg, 0.44 mmol) in MeOΗ (13 mL) at room temperature under an argon atmosphere was added all at once sodium borohydride (200 mg, 5.40 mmol). After stirring at room temperature for 3 h, the mixture was warmed to 40°C for 10 min and then allowed to cool to room temperature. The pΗ was adjusted to 6 with dilute acetic acid, and the solvent was evaporated under reduced pressure. Water was added to the residue, and the mixture was cooled to 0°C. The solid which formed was collected by filtration, washed with cold Η2O and dried in vacuo to give the title compound as a hydrate. ^JH NMR (DMSO-d6) d 8.52 (br s, IH), 8.10 (br d, IH), 7.61 (s, IH), 7.55 (obscured dd, IH), 7.31 (s, IH), 6.70 (d, J = 4.6 Hz, IH), 5.44 (br s, 2H), 5.20 (br s, 2H), 4.98 (d, / = 4.6 Hz, IH), 4.89 (s, IH), 4.56 (d, 2H), 3.80 (m, 2H), 3.50 (m, 2H), 3.22 (s, 3H), 1.72 (br q), 0.90 (br t, 3H). Anal. Calcd for C24H26N2O7-1/2 H2O: C, 62.19; H, 5.87; N, 6.04. Found: C, 62.19; H, 5.80; N, 5.81.

3C. 8-Formyloxymethyl-2-rf2-methoxyethoxy methoxyl-7-(l-oxopropylV indolizinor 1.2-frlquinolin-9( 11 HVone.

To a suspension of (4S,3R,S)-4-ethyl-3,4-dihydrox-9-[(2- methoxyethoxy)methoxy]- lH-pyrano- [3',4': 6,7]indolizino[ 1 ,2-b]quinolin- 14(4H,12H)-one (500 mg, 1.10 mmol) in glacial acetic acid (35 mL) was added dropwise a solution of sodium metaperiodate (355 mg, 1.65 mmol) in Η2O (10 mL). The resulting mixture was stirred at room temperature for 4 h at which time ethylene glycol (0.5 mL) was added. Water (175 mL) was added, and the mixture was allowed to stand at 0°C overnight. The mixture was concentrated under reduced pressure to about 25 mL, and the residue was cooled to 0°C. The solid which formed was collected by filtration and dried in vacuo. A portion (25 mg) of this was purified by radial chromatography on silica gel, eluting with a solvent gradient of 2-5%MeOH/CH2Cl2 to provide the title compound (10 mg). ^U NMR (CDCI3) d 8.27 (br s, IH), 8.11 (obscured m, IH), 8.09 (s, IH), 7.53 (dd, J = 5.3 Hz, /= 2.9 Hz, IH), 7.49 (s, IH), 7.23 (s, IH), 5.44 (s, 2H), 5.33 (s, 2H), 5.28 (d, / = 0.9 Hz, 2H), 3.88 (m, 2H), 3.58 (m, 2H), 3.38 (s, 3H), 2.95 (q, / = 7.1 Hz, 2H), 1.26 (t, 7 = 7.1 Hz, 3H). Anal. Calcd for C24H24N2O7: C, 63.71; H, 5.35; N, 6.19. Found: C, 63.85; H, 5.56; N, 5.33.

3D. r± 3-Kthvl- 1.11 -dihvdro-3-hvdroxv-8-rr2-methoxvethoxv^methoxv1- 3H.1 H-furor3'.4': 6.71indolizonor 1.2-frlαuinolin- 13-one. To a solution of 8-formyloxymethyl-2-[(2-methoxyethoxy)methoxy]-7-(l- oxopropyl)indolizino[l,2-b]quinolin-9(llH)-one (420 mg, 0.93 mmol) in 1:2 MeOΗ/CΗ₂Cl2 (100 mL) was added a slurτy of silica gel in 1 :2 MeOH/CH₂CI₂ (20 mL). The resulting mixture was heated at reflux for 6 hours, then allowed to cool to room temperature, and stirred for 60 hours. The mixture was filtered, and the filtrate was evaporated under reduced pressure. The solid residue was dissolved in CH2CI2, washed with H2O (2x20 mL) and dried (Na2SO4). The solvent was removed in vacuo, and the residue was recrystallized from MeOH to give the title compound. -1H NMR (CDCI3) d 8.04 (s, IH), 7.70 (m, IH), 7.30 (m, 2H), 7.15 (s, IH), 5.69 (s, IH), 5.40 (s, 2H), 5.10 (m, 2H), 4.94 (m, 2H), 3.90 (m, 2H), 3.62 (m, 2H) 3.41 (s, 3H), 2.3-1.95 (m, 2H), 0.87 (t, J = 7.2 Hz, 3H). Anal. Calcd for C₂3H₂4N₂O₆.5/8 H₂O: C, 63.40; H, 5.62; N, 6.43. Found: C, 63.27; H, 5.66; N, 6.23.

Example 4 M-V3-Ethyl-1H. 3H-fiιror3^,.4':6.71indoli2 nori.2-Wquinolin-1.13fl l/Λ-dιnne. This compound was prepared by the method of R. P. Hertzberg, M. J. Caranfa, K. G. Holden, D. R. Jakas, G. Gallagher, M. R. Mattern, S.-M. Mong, J. O eary Bartus, R. K. Johnson, and W. D. Kingsbury /. Med. Chem., 1989, 32, 715.

Example 5 3-Ethyl-l lH.13H-furor3'.4':6.71indolizinori .2-blQuinolin-l 3-one.

A solution of 32 mg (0.10 mmol) (+)-3-ethyl-l,l l-dihydro-3-hydroxy- 3H,13H-furo[3',4':6,7]indolizino[l,2-&]quinolin-13-one in 0.5 mL trifluoroacetic acid was stirred at room temperature for 30 min, and then the trifluoroacetic acid was evaporated in vacuo. The red residue was covered with 0.5 mL methylene chloride, and a few drops each of triethylamine and methanol were added to convert it to a golden solution that was chromatographed on silica gel using 3% methanol in methylene chloride as elution solvent. The yellow solid obtained was recrystalUzed from methanol to give yellow crystals of the title compound as a hydrate, mp 226.5- 228.5°C. -1H NMR (CDCI3/ MeOΗ-d4) d 8.21 (s, IH), 8.15 (s, IH), 8.13 (d obscured by overlapping s, IH), 7.80 (d, / = 8.2 Hz, IH), 7.74 (m, IH), 7.55 (apparent dt, / = 8.0 Hz, / = 0.9 Hz, IH), 7.34 (s, IH), 5.17 (d, J = 0.8 Hz, 2H), 2.98 (q, J = 7.6 Hz, 2H), 1.39 (t, J = 7.5 Hz, 3H). Anal. Calcd for

C19H14N2O2-1/2 H2O: C, 73.29; H, 4.86; N, 9.00. Found: C, 73.16; H, 4.94; N, 8.88.

Example 6 Parenteral Composition

To prepare a parenteral pharmaceutical composition of this invention suitable for administration by injection, 100 mg of a water soluble salt of a compound of Formula I is mixed with 10 ml of 0.9% sterile saline, and the mixture is incorporated into a dosage unit form suitable for administration by injection.

Exam le 7

Oral Composition

To prepare an oral pharmaceutical composition of this invention, 100 mg of a compound of Formula I is mixed with 750 mg of lactose, and the mixture is incorporated into an oral dosage unit form, such as a hard gelatin capsule, which is suitable for oral administration.

Claims

We claim:

1. A method for treating viral infections comprising administering to an infected host in need thereof an effective amount of a compound of Formula I, or a pharmaceutically acceptable salt thereof, alone or in combination with a carrier, diluent or excipient

wherein:

R⁷ is -H, -CN, lower alkyl or -(CH2)_nCH2V where n=0-3;

R9 is -H, -OR, -NRR¹, -CN, -(CH2)_nCH2V where n=0-3;

R¹⁰ is -H, -OR, -OCH2OCH2CH2OCH3, -NRR¹, -CN, -COR¹², -CH(OH)R¹², - O-(CH2)l-5CH2NRR¹, -OC(O)NRR¹, l,4'-bipiperidine-l'-carboxy, -(CH2)_nCH2V where n=0-3;

V is -OH, -OCOR¹⁴, OP(O)(OH)R¹⁵ or -NRR¹;

R^ is -H or -OR;

R¹² is -H or lower alkyl;

R¹^ is lower alkyl;

R and R¹ are independently selected from the group consisting of -H, -Ci-6 alkyl, and, when R and R¹ are substituted on nitrogen, R and R¹ can be taken together to form a 5-7 membered saturated heterocyclic ring containing the nitrogen;

R¹⁴ is -CR¹²R¹⁶R¹⁷;

-(CH₂)_nCH₂R¹⁷ (where n=l-3); CH— NH

(where n=0 or 1, and CH2R¹ can be substituted on the phenyl at the 2, 3, or 4 position);

-O(CH₂)nCH₂R¹⁷ (where n = 1-3);

-NRR¹;

-NH(CH₂)_nCH₂R¹⁷ (where n = 1-3);

R¹⁵ is OH, OR¹⁸ or CH₂NH2J

R¹*-^* is H or the side chain of any naturally occuring α-amino acid;

where X is any pharmaceutically acceptable anion;

R¹⁸ is lower alkyl;

Q is CR²R¹² and T is CH₂ or C=O,or

Q is CR and T is CH;

the dotted lines represent a double bond between carbons 3a and 13a, a single bond between carbons 1 and 13a, and a single bond between carbons 3 and 3a when Q is CR²R¹² and T is CH₂ or C=O; and the dotted lines represent a single bond between carbons 3a and 13a, a double bond between carbons 1 and 13a, and a double bond between carbons 3 and 3a, when Q is CR and T is CH.

R² is -H, -OR, or -OC(O)R;

provided that:

if one of R⁷, R⁹ , R¹⁰ or R¹¹ is other than -H, only one of the others may be other than -H; and only one of R⁹ or R¹⁰ may be or -NRR¹.

2. The method of claim 1 wherein said compound is of Formula II

II or a pharmaceutically acceptable salt thereof, wherein the substituents are the same as defined for Formula I, except that:

Q is CR²R¹²; and

T is CH₂ or C=O;

provided that:

if one of R⁷, R⁹ , R¹⁰ or R¹¹ is other than -H, only one of the others may be other than -H;

only one R⁹ or R¹⁰ may be -NRR¹.

3. The method of claim 2 wherein: T is C=O; R² is -H; R¹² is lower alkyl; and R⁷, R⁹, R^J0, and R¹¹ are all -H.

4. The method of claim 3 wherein said compound is 3-ethyl-3, 11-dihydro- 1H, 13H-furo[3',4':6,7]indolizino[ 1 ,2-b]quinolin- 1 , 13-dione.

5. The method of claim 2 wherein: R⁷, R⁹ and R¹¹ are all -H; R¹⁰ is -H, -OR, or -OCH₂OCH₂CH₂OCH3; T is CH₂; R² is OR; and R¹² is lower alkyl.

6. The method of claim 5 wherein R¹⁰ is -H.

7. The method of claim 6 wherein said compound is 3-ethyl- 1,11 -dihydro-3- hydroxy-3H, 13H-furo[3',4':6,7]-indolizino[ 1 ,2-fc]quinolin- 13-one.

8. The method of claim 6 wherein said compound is 3-ethyl- 1,11 -dihydro-3- methoxy-3H, 13H-furo[3^,4':6,7]-indolizino[ 1 ,2-&]quinolin- 13-one.

9. The method of claim 5 wherein R¹⁰ is -OCΗ₂OCΗ₂CΗ₂OCΗ3.

10. The method of claim 9 wherein said compound is 3-ethyl- 1, 1 l-dihydro-3- hydroxy-8-[(2-methoxyethoxy)methoxy]-3H,13H-furo[3',4':6,7]indolizono[l,2- fc]quinolin-13-one.

11. The method of claim 1 wherein said compound is of Formula III, or a pharmaceutically acceptable salt thereof,

III wherein the substituents are the same as defined for Formula I.

12. The method of claim 11 where R is lower alkyl.

13. The method of claim 12 where R⁷, R⁹, R¹⁰, and R¹¹ are all -Η.

14. The method of claim 13 wherein said compound is 3-ethyl- 11Η, 13Η- furo[3',4':6,7]indolizino[l,2-£]quinolin-13-one.

15. A compound of Formula II, or a pharmaceutically acceptable salt thereof

II wherein:

R⁷ is -H, -CN, lower alkyl or -(CH2)_nCH2N where n=0-3;

R9 is -H, -OR, -ΝRR¹, -CΝ, -(CH2)_nCH2V where n=0-3;

R^ΪO is -H, -OR, -OCH2OCH2CH2OCH3, -ΝRR¹, -CΝ, -COR¹², -CH(OH)R¹², - O-(CH2)l-5CH2ΝRR¹, -OC(0)NRR¹, l,4^*-bipiperidine-l'-carboxy, -(CH2)_nCH2V where n=0-3;

V is -OH, -OCOR¹⁴,

or -NRR¹;

R¹1 is -H or -OR;

R¹² is -H or lower alkyl;

R¹^ is lower alkyl;

R and R¹ are independently selected from the group consisting of -H, -Ci-6 alkyl, and, when R and R¹ are substituted on nitrogen, R and R¹ can be taken together to form a 5-7 membered saturated heterocyclic ring containing the nitrogen;

R¹⁴ is -CR¹²R¹⁶R¹⁷;

-(CH₂)_nCH2R¹⁷ (where n=l-3); CH— NH

(where n=0 or 1, and CH2R¹⁷ can be substituted on the phenyl at the 2, 3, or 4 position);

-O(CH2)_nCH₂R¹⁷ (where n = 1-3);

-NRR¹;

-NH(CH₂)_nCH2R¹⁷ (where n = 1-3);

R¹⁵ is OH, OR¹⁸ or CH₂NH2;

R¹^ is H or the side chain of any naturally occuring α-amino acid;

_Rπ_isNRRι_,

. -^N where X is any pharmaceutically acceptable anion;

R¹⁸ is lower alkyl;

QisCR²R¹²;

TisCH₂orC=O;

R²is-H,-OR,or-OC(O)R;

provided that:

if one of R⁷, R⁹ , R¹⁰ or R^{1 J} is other than -H, only one of the others may be other than -H; only one of R⁹ or R¹⁰ may be -NRR¹;

R⁷, R⁹, R¹⁰, and R¹¹ are not all -H when T is C=O and Q is C(H)(CH₂CH3); and

R⁷, R⁹, R¹⁰ and R¹¹ are not all -H when T is CH₂ and Q is C(OH)(CH₂CH₃).

16. A compound of claim 15 wherein: T is C=O; R² is -H; and R¹² is lower alkyl.

17. A compound of claim 16 wherein: R⁷, R⁹, R¹⁰, and R¹¹ are all -H; and provided that R¹² is not CH2CH3.

18. A compound of claim 15 wherein: T is -CH₂; R² is -OR; and R¹² is lower alkyl.

19. A compound of claim 18 wherein: R⁷, R⁹ and R¹¹ are all -H; and R¹⁰ is -H, -OR, or -OCH₂OCH₂CH₂OCH₃.

20. A compound of claim 19 wherein said compound is 3-ethyl- 1,11 -dihydro-3- methoxy-3H, 13H-furo[3'4':6,7]-indolizino[ 1 ,2-fc]quinolin- 13-one.

21. A compound of claim 19 wherein R¹ * is -OCΗ₂OCΗ₂CΗ₂OCΗ₃.

22. A compound of claim 21 wherein said compound is 3-ethyl- 1,11 -dihydro-3- hydroxy-8-[(2-methoxyethoxy)methoxy]-3H,13H-furo[3',4':6,7]indolizono[l,2-

6]quinolin-13-one.

23. A compound of Formula III

ffl or a pharmaceutically acceptable salt thereof, wherein:

R⁷ is -H, -CN, lower alkyl or -(CH2)_nCH2V where n=0-3;

R9 is -H, -OR, -NRR¹, -CN, -(CH2)_nCH2V where n=0-3;

R¹⁰ is -H, -OR, -OCH2OCH2CH2OCH3, -NRR¹, -CN, -COR¹², -CH(OH)R¹², - O-(CH2)l-5CH2NRR¹, -OC(0)NRR¹, l,4'-bipiperidine-l'-carboxy, -(CH2)_nCH2V where n=0-3;

V is -OH, -OCOR¹⁴, 0_ 0)(GH)R¹⁵ or -NRR¹;

Rⁿ is -H or -OR;

R¹² is -H or lower alkyl;

R¹^ is lower alkyl;

R and R¹ are independently selected from the group consisting of -H, -Ci-6 alkyl, and, when R and R¹ are substituted on nitrogen, R and R¹ can be taken together to form a 5-7 membered saturated heterocyclic ring containing the nitrogen;

R¹⁴ is -CR¹²R¹⁶R¹⁷;

-(CH₂)_nCH₂R¹⁷ (where n=l-3); CH— NH

JJ .

(where n=0 or 1, and CH2R¹ can be substituted on the phenyl at the 2, 3, or 4 position);

-O(CH₂)nCH₂R¹⁷ (where n = 1-3);

-NRR¹;

-NH(CH₂)nCH₂R¹⁷ (where n = 1-3);

R¹⁵ is OH, OR¹⁸ or CH₂NH₂;

R¹ ^ is H or the side chain of any naturally occuring α-amino acid;

where X is any pharmaceutically acceptable anion;

R¹⁸ is lower alkyl;

provided that:

if one of R⁷, R⁹ , R¹⁰ or R¹¹ is other than -H, only one of the others may be other than -H; and

only one of R⁹ or R¹⁰ may be -NRR¹.

24. A compound of claim 23 where R is lower alkyl.

25. A compound of claim 24 where R⁷, R⁹, R¹⁰, and R¹ * are all -H.

26. A compound of claim 25 wherein said compound is 3-ethyl- 1 IH, 13H- furo[3',4':6,7]indolizino[ 1 ,2-&]quinolin- 13-one.

27. A formulation comprising a compound as claimed in claim 15 in admixture with a carrier.

28. The formulation of claim 27 wherein the carrier is a pharmaceutically acceptable excipient.

29. A formulation comprising a compound as claimed in claim 23 in admixture with a carrier.

30. The formulation of claim 29 wherein the carrier is a pharmaceutically acceptable excipient.

31. The method of claim 1 where the viral infection is caused by a herpes simplex virus.

32. The method of claim 31 wherein said virus is herpes simplex type 1 and the infected host is a mammal.

33. The method of claim 31 wherein said virus is herpes simplex type 2 and the infected host is a mammal.

34. The method of claim 1 wherein said virus is cytomegalovirus and the infected host is a mammal.

35. The method of claim 1 wherein said virus is varicella zoster and the infected host is a mammal.