WO2020157626A1 - Novel purine derivatives and drugs comprising same - Google Patents

Abstract

The invention relates to a compound of general formula (I) or a pharmaceutically acceptable enantiomer, tautomer, salt, solvate or prodrug of said compound, or a mixture thereof, and to the use of said compound as a drug, in particular as an antiviral drug, especially for use in the treatment of a disease or disorder caused by a virus. [Chem.60] X= O or CH2; R1= H, OH, NH2; R2= H, NH2, -NH-benzoyle, OH, Cl; R3, R4 and R5 have various meanings.

Description

NEW PURINE DERIVATIVES AND DRUGS CONTAINING THEM

The present invention relates to novel purine derivatives and drugs comprising them, in particular antiviral drugs comprising them.

Herpes virus (HV) is widely distributed in nature and is a pathogen in animals and humans. They are large DNA viruses (80 to 100 nanometers) that have a common biological property, their ability to establish latent infections which can lead to recurring symptoms, especially in immunocompromised people. Infections with viruses of the herpes family (HV) are linked to a large number of human diseases that constitute a public health problem. The morbidity produced by these acute and recurrent infections ranging from skin lesions to encephalitis, infectious diseases, whether genital or not, to immunological diseases, which causes many public health problems. Control and treatment of the disease is therefore now a necessity, either by immunization (vaccines) or by administration of an effective antiviral treatment.

Currently, eight species of HV have been identified. They are classified into three sub-families whose classification is based on the differences in the biological properties of viruses (such as size and content of the genome, immunological response, cell tropism): alpha-, beta and gammaherpesvirinae (Table 1 ), Davison, A., et al., The order Herpesvirales. Archives of Virology, 2009. 154 (1): p. 171-177.

Subfamily	Last name	Abbreviation	Disease
Alphaherpesvirinae	Herpes Simplex virus type-1	HSV-1 / HHV-1	Orofacial
	Herpes Simplex virus type-2	HVS-2 / HHV-2	Genital
	Varicella-Zoster virus	VZV / HHV-3	Chickenpox and shingles (herpes zoster)
Betaherpesvirinae	Cytomegalovirus	CMV / HHV-5	Congenital infection
	Human Herpesvirus-6	HHV-6	Roseola infant
	Human Herpesvirus-7	HHV-7
Gammaherpesvirinae	Epstein-Barr virus	EBV / HHV-4	Mononucleosis
	Virus associated with Kaposi syndrome or "Kaposi Sarcoma"	KSHV / HHV-8	Kaposi's disease

The eight species of viruses of the Herpesviridae family identified commonly infect humans. It is estimated that nearly 100% of the adult population has already been infected with at least one of these limbs. HSV type 1 (oro-labial) and 2 (genital), CMV, EBV and VZV are the five members associated with most health problems caused by HV, Grinde, B., Herpesviruses: latency and reactivation - viral strategies and host response. Journal of Oral Microbiology, 2013. 5: p. 22766 / 1-22766 / 9. and Gray, F., Role of microRNAs in herpesvirus latency and persistence. Journal of General Virology, 2015. 96 (4): p. 739-751.

A large portion of the world's population is infected with HSV types 1 and 2. Although the overall prevalence and distribution of HSV infections cannot be accurately established due to the low availability of seroepidemiological data, general trends indicate that infections with HSV-1 are more prevalent in the world than infection with HSV-2 and that more than one billion people worldwide are infected with HSV-2, Samandary, S., et al. , Associations of HLA-A, HLA-B and HLA-C alleles frequency with prevalence of herpes simplex virus infections and diseases across global populations: Implication for the development of an universal CD8 + T-cell epitope-based vaccine. Human Immunology, 2014. 75 (8): p. 715-729.

About 0.7% of all newborns in the United States are infected with CMV. Nearly 20% of infected newborns are born with, or will develop, permanent sequelae, such as hearing loss, vision loss, cerebral palsy or cognitive impairment, Cannon, MJ, Congenital cytomegalovirus ( CMV) epidemiology and awareness. Journal of Clinical Virology, 2009. 46, Supplement 4: p. S6-S10.

The EBV virus is very common. In the United States, 90% of adults tested are positive for anti-EBV antibodies by the age of 35. In contrast, the prevalence in children is lower, varying between 20% to 80% depending on age and geographic area, Balfour, HH, et al., Age-Specific Prevalence of Epstein – Barr Virus Infection Among Individuals Aged 6–19 Years in the United States and Factors Affecting Its Acquisition. Journal of Infectious Diseases, 2013. 208 (8): p. 1286-1293.

The worldwide distribution of VZV infection is non-seasonal. Seroprevalence varies from 30-100% depending on age, geographic area, ethnic and socio-economic origin. In general, the prevalence in poor countries is close to 100% and infections are normally acquired in early childhood. In the United States, the seroprevalence of VZV is in the order of 40 to 50%. People in developed countries tend to have lower seroprevalence rates. In these countries, infections are often acquired during adolescence and adulthood, with higher rates in less advantaged socioeconomic populations. About 20% to 30% of preschoolers are infected with VZV, Sanghavi, SK, DT Rowe, and CR Rinaldo. Cytomegalovirus, Varicella-Zoster virus, and Epstein-Barr virus . 2009. American Society for Microbiology. Analysis of studies conducted in different countries have shown an incidence of Herpes Zoster (shingles) of 4-4.5 per 1000 people per year. All studies have shown an increased incidence in adult individuals, particularly after age 50, Yawn, BP and D. Gilden, The global epidemiology of herpes zoster. Neurology, 2013. 81 (10): p. 928-30.

Today herpes virus infections can be effectively treated with antiviral drugs. Standard therapy includes drugs that share a common mechanism of action: they compromise the synthesis of viral DNA by inhibiting viral DNA polymerase. The drugs of choice are Aciclovir (ACV), Ganciclovir (GCV), Penciclovir (PCV) and their prodrugs such as Valaciclovir (VACV) and Famciclovir (FCV). Prolonged use of these drugs is associated with the development of resistant strains, especially in immunocompromised patients. Another factor limiting their use is the high toxicity they present, Hodge, RAV and HJ Field, Antiviral agents for herpes simplex virus. Advances Pharmacol. (San Diego, CA, US), 2013. 67 (Antiviral Agents): p. 1-38, Skoreński, M. and M. Sieńczyk, Anti-herpesvirus agents: a patent and literature review (2003 to present). Expert Opinion on Therapeutic Patents, 2014. 24 (8): p. 925-941, James, SH and MN Prichard, Current and future therapies for herpes simplex virus infections: mechanism of action and drug resistance. Current Opinion in Virology, 2014. 8 (0): p. 54-61, Vadlapudi, AD, RK Vadlapatla, and AK Mitra, Update on emerging antivirals for the management of herpes simplex virus infections: a patenting perspective. Recent Pat. Anti-Infect. Drug Discovery, 2013. 8 (1): p. 55-67.

There is therefore a need for new antiviral compounds useful in the treatment of viruses, in particular of the herpes family.

To this end, the invention relates to a compound of general formula (I):

(I)

or a pharmaceutically acceptable enantiomer, tautomer, salt, solvate or prodrug thereof, or a mixture thereof,

general formula (I) in which:

X represents O or CH ₂ ;

R ₁ represents: H, OH, NH ₂ ;

R ₂ represents: H, NH ₂ , -NH-benzoyl, OH, Cl;

R ₃ represents H;

R ₄ represents H; OH ; or OR ₆ where R ₆ represents:

with R ' ₆ representing C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl or alternatively -CHR-NH ₂ , the latter representing the residue of a natural α-amino acid; R ₆ may also represent -SiR ₇ R ₈ R ₉ , where R ₇ , R ₈ and R ₉ each independently represent C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl; or

R ₃ and R ₄ together with the carbon atom to which they are attached represent

;

R ₅ represents:

OH ;

-OSiR ₁₀ R ₁₁ R ₁₂ , wherein R ₁₀ , R ₁₁ and R ₁₂ each independently represent C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl;

, wherein R ₁₃ and R ₁₄ each independently represent H, C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl;

, where n is 0 or 1 and R ₁₅ and R ₁₆ each independently represent H, C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl;

, wherein R ₁₇ , R ₁₈ and R ₁₉ each independently represent H, C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl;

-OC (O) R ₂₀ , where R ₂₀ represents C ₁ -C ₆ alkyl, C ₅ -C ₁₂ aryl or alternatively -CHR'-NH ₂ , the latter representing the residue of a natural α-amino acid;

the alkyl and aryl radicals falling within the definition of R ' ₆ , R ₇ to R ₂₀ possibly being substituted,

the compounds of general formula (I), their enantiomers, tautomers, pharmaceutically acceptable salts, solvates or prodrugs or mixtures for which R ₁ represents OH being represented in said formula (I) in their tautomeric form:

As an example of C ₁ -C ₆ alkyl radicals, mention may be made of methyl, ethyl, isopropyl, methyl-2-propyl.

As an example of C ₅ -C ₁₂ aryl radicals, mention may be made of phenyl.

As substituents on the C ₁ -C ₆ alkyl and C ₅ -C ₁₂ aryl radicals, mention may be made of amino, carboxylic acid, carboxamido, fluoro, chloro, hydroxy, methoxy.

As R or R 'of the formulas –CHR-NH ₂ (falling within the definition of R' ₆ ) and –CHR'NH ₂ (falling within the definition of R ₂₀ ), we can mention, among others, H, methyl, isopropyl , which correspond respectively to the residues of the amino acids glycine, alanine and valine.

The compounds of the invention may contain one or more asymmetric centers and therefore may exist in different stereoisomeric forms. Therefore, the present invention includes all possible stereoisomers and includes not only racemic mixtures but also individual enantiomers but also their non-racemic mixtures. When it is desired to obtain an individual enantiomer, this can be obtained by stereospecific synthesis, by resolution of the final product or any suitable intermediate, or by chiral chromatographic methods, as known in the art. . Resolution of the final product, intermediate or starting material can be accomplished by any suitable method known in the art.

The compounds of the invention can be provided in the form of pharmaceutically acceptable salts. Pharmaceutically acceptable salts of the compounds of the invention include addition salts with acids and addition salts with bases.

Addition salts with the appropriate acids are formed from acids which form non-toxic salts. Examples include acetate, adipate, aspartate, benzoate, besylate, bicarbonate / carbonate, bisulfate / sulfate, borate, camsylate, citrate, cyclamate, edisylate, esylate, formate, fumarate, gluceptate, gluconate, glucuronate, hexafluorophosphate, hibenzate, / chloride, hydrobromide / bromide, iodide / iodide, isethionate, lactate, malate, maleate, malonate, mesylate, methylsulfate, naphthylate, 2-napsylate, nicotinate, nitrate, orotate, oxalate, palmitate, pamoate, phosphate / hydrogénophénosphate, pyroglosphate , saccharate, stearate, succinate, tannate, tartrate, tosylate, trifluoroacetate and xinofoate

Addition salts with the appropriate bases are formed from bases which form non-toxic salts.

Examples include the salts of aluminum, arginine, benzathine, calcium, choline, diethylamine, diolamine, glycine, lysine, magnesium, meglumine, olamine, potassium, sodium, tromethamine, 2- (diethylamino) ethanol, ethanolamine, morpholine, 4- (2-hydroxyethyl) morpholine and zinc.

Acid and base hemi-salts can also be formed, for example, the hemisulfate and hemi-calcium salts.

Preferred pharmaceutically acceptable salts include hydrochloride / chloride, hydrobromide / bromide, bisulfate / sulfate, nitrate, citrate, and acetate.

When the compounds of the invention contain an acid group and a basic group, the compounds of the invention can also form internal salts, and such compounds are within the scope of the present invention. When the compounds of the invention contain a hydrogen donor heteroatom, the invention also covers salts and / / isomers formed by transferring said hydrogen atom to a basic atom or group in the molecule.

Pharmaceutically acceptable salts of compounds of the invention can be prepared by one or more of these methods:

1. by reacting the compound of the invention with the desired acid;
2. by reacting the compound of the invention with the desired base;
3. by displacement of an acid labile or base labile protecting group of a suitable precursor of the compound of the invention or by ring opening of a suitable cyclic precursor, for example, a lactone or a lactam, using the desired acid; or
4. by converting one salt of the compound of the invention to another by reaction with a suitable acid or by means of a suitable ion exchange column.

All of these reactions are typically carried out in solution. The salt can precipitate from solution and be collected by filtration or can be recovered by evaporating the solvent. The degree of ionization in salt can vary from completely ionized to virtually non-ionized.

All references to compounds of the invention include references to their enantiomers, salts, solvates, polymorphs, multicomponent complexes and liquid crystals.

The compounds of the invention include the compounds of the invention as defined above, including all of their crystalline polymorphs and habits, prodrugs and isomers (including optical, geometric and tautomers) and isotopically labeled compounds.

In particular :

R ₁ represents OH and R ₂ represents NH ₂ ; or

R1 represents NH2 and R2 represents H or Cl.

Even more particularly:

R ₁ represents OH, R ₂ represents NH ₂ , R ₃ represents H and R ₄ represents H or OH, or R ₃ and R ₄ together with the carbon atom to which they are attached represent

.

Even more particularly, R ₅ represents OH.

The compounds according to the invention can consist of a cis compound of formula:

or

or in a trans compound of formula:

or

or mixtures thereof, R ₁ , R ₂ , R ₅ and X being as defined above.

In particular, the compounds according to the present invention can consist of a compound of formula:

or

or

..

The compounds of the invention can be prepared according to the following first general scheme:

Bromination: The starting compound is brominated on a scale of 1 to 5 g at room temperature with excellent yield.

Protection: the hydroxyl functions carried by the brominated derivatives obtained are silylated, on a scale of 0.5 to 1 g, with t-butyldimethylsilyl chloride in the presence of imidazole at room temperature.

Cyclization: the cyclization of the disilylated compounds obtained is carried out under reflux in freshly distilled acetonitrile on a scale of 150 to 200 mg in the presence of AIBN and tributyltin hydride.

Deprotection: the cyclized compounds were desilylated by treatment with either trifluoroacetic acid (TFA) or hydrofluoric acid (HF) in pyridine or tetrabutylammonium fluoride (TBAF) to lead to compounds of antiviral interest of invention.

The compounds of the invention can also be prepared according to the following second general scheme:

Protection: one of the hydroxyl functions of the starting compound is monosilylated with t-butyldimethylsilyl chloride in the presence of imidazole at room temperature.

Sulfonylation, for example mesylation or tosylation: the remaining hydroxyl function is sulfonylated using a sulfonyl chloride such as mesyl chloride in the presence of pyridine or of N, N -dimethylaminopyridine.

Sulfurization: mesyl (sulfonyl) and monosilyl derivatives are transformed into phenylsulfides or other sulfides using sodium phenylthiolate or the corresponding thiolates.

Cyclization: the phenylsulfide derivatives are allowed to react under reflux in freshly distilled acetonitrile in the presence of AIBN and tributyltin hydride to lead to the silylated cyclized derivatives.

The cyclized compounds obtained can be deprotected to obtain a compound where R ₃ = R ₄ = H and R ₅ = OH, or oxidized then reduced and then deprotected to obtain a compound where R ₄ = R ₅ = OH.

Deprotection in the two cases above: it is carried out with TBAF or TFA or HF / pyridine.

Oxidation then reduction: the silylated cyclized derivatives obtained are oxidized using selenium oxide to obtain a carbonyl derivative, the latter being reduced with sodium borohydride, according to the following equation:

The carbonyl derivative obtained by oxidation can thus be reduced to give a mixture of cis / trans isomers in equivalent proportions, which mixture can be used to separately isolate the cis isomers and the trans isomers.

The compounds obtained can then be transformed, at the level of the primary alcohol function, according to the following third general scheme:

In order to obtain an ester group in R5, the acylation can be carried out with the corresponding carboxylic acid in the presence of a coupling agent (carbodiimide) and by using a series of protection and deprotection steps as developed in the literature in the nucleoside series (tritylation, silylation, etc.) in the case where R ₄ = OH.

Phosphorylation can be carried out according to the methods described in the literature from derivatives of phosphoric acid.

The formation of phosphonate and phosphoramidate groups can be accomplished using standard reactions known in the art.

The compounds obtained can also be converted, at the level of the primary and secondary alcohol functions, according to the following fourth general scheme where R ₂₀ is as defined above:

Such acylation can be carried out with the corresponding carboxylic acid in the presence of a coupling agent (carbodiimide).

The cis isomers are mainly formed according to the first general scheme. They can be oxidized and then reduced, for example as described above in the case of the second general scheme, to obtain a mixture of cis / trans isomers in equivalent proportions, a mixture which can be used to obtain the isomers in greater quantity. trans:

The invention also relates to a pharmaceutical composition comprising at least one compound of general formula (I) as defined above or an enantiomer, a tautomer, a salt, a solvate or a pharmaceutically acceptable prodrug of this compound and at least one. pharmaceutically acceptable carrier.

The invention also relates to a compound or a pharmaceutical composition as described above for use as a medicament, in particular in the treatment of a disease or disorder caused by a virus.

In particular, the virus is a virus from the herpes family.

More particularly, the virus is a virus of the herpes family chosen from: the Herpes Simplex virus type 1 (HSV-1), the Herpes Simplex virus type 2 (HSV-2), the Feline Herpes Virus and the Varicella Zoster virus (VZV).

The invention also covers all pharmaceutically acceptable prodrugs and premedrugs of the invention.

Dosage

In one embodiment, the therapeutically effective amount is in the range of about 10 to about 10,000 mg / ml of the composition, pharmaceutical composition or medicament of the invention, preferably 100 to about 5,000 mg / ml, of more preferably from about 200 to about 2000 mg / ml of the composition, pharmaceutical composition or drug of the invention.

In one embodiment, the therapeutically effective amount is in the range of about 10 to about 10,000 mg / g of the composition, pharmaceutical composition or drug of the invention, preferably 100 to about 5,000 mg / g, of more preferably from about, 200 to about 2000 mg / g of the composition, pharmaceutical composition or drug of the invention.

It will be understood that the total daily use of the compound of the invention, the pharmaceutical composition and the medicament of the present invention will be decided by the attending physician within the scope of their medical judgment. The specific therapeutically effective dose level for any particular patient will depend on a variety of factors including the disorder being treated and the severity of the disorder; the activity of the specific compound employed; the specific composition employed; the patient's age, body weight, general health, sex and diet; duration of administration, route of administration, and rate of excretion of the specific compound used; the duration of treatment; drugs used in combination or simultaneously with the specific compound used; and the like factors well known in the medical art.

For example, it is well within the skill of those skilled in the art to start with doses of the compound at levels lower than those required to achieve the desired therapeutic effect and gradually increase the dosage until the dose is reached. desired effect is obtained. However, the daily dosage of the products can be varied over a wide range from about 10 to about 10,000 mg per adult per day, preferably 100 to about 5000, more preferably from about 200 to about 2000 mg per adult. per day. Preferably, the compositions contain 10, 50, 100, 250, 500, 1000 and 2000 mg of the active principle for the symptomatic adjustment of the dosage to the patient to be treated. A medicament typically contains about 10 to about 10,000 mg of the active ingredient, preferably 100 to about 5,000, more preferably about 200 to about 2000 mg of the active ingredient. An effective amount of the drug is usually provided at a dosage ranging from 0.1 mg / kg to about 100 mg / kg of body weight per day, preferably about 1 mg / kg to 40 mg / kg of body weight. per day, more preferably about 2 mg / kg to 20 mg / kg of body weight per day.

Route of administration

In the pharmaceutical compositions of the present invention, the active ingredient, alone or in combination with another active ingredient, can be administered in unit dosage form, in the form of a mixture with conventional pharmaceutical carriers, to animals. and human beings. Suitable unit dosage forms include those suitable for the oral route such as tablets, capsules, powders, granules and oral suspensions or solutions, sublingual and buccal administration forms, aerosols, implants, subcutaneous, transdermal, topical, intraperitoneal, intramuscular, intravenous, subdermal, transdermal, intrathecal and intranasal administration forms and rectal administration forms.

In one embodiment, the composition, pharmaceutical composition or medicament contains vehicles which are pharmaceutically acceptable for formulation suitable for oral administration.

Examples of forms suitable for oral administration include, but are not limited to, tablets, orodispersion tablets, effervescent tablets, powders, granules, pills (including sweetened pills), dragees, capsules (including soft gelatin capsules), syrups, liquids, gels or other solutions, suspensions, slurries, liposomal forms and the like.

In one embodiment, the composition, pharmaceutical composition or medicament contains vehicles which are pharmaceutically acceptable for a formulation suitable for injection.

Examples of forms suitable for injection include, but are not limited to solutions, such as, for example, sterile aqueous solutions, dispersions, emulsions, suspensions, solid forms suitable for use in preparing solutions or suspensions by adding a liquid before use, for example, powder, liposomal forms or the like.

Processing method

The present invention also relates to a method of treating a disease or disorder caused by a virus, and in particular a virus of the Herpes virus family, in a subject in need thereof, comprising administering to the subject of a therapeutically acceptable amount of a compound of the invention described above.

The following examples illustrate the present invention without, however, limiting its scope. In these examples, the following abbreviations were used:

TBDMSCl: tert -butyldimethylsilyl chloride

AIBN: azobisisobutyronitrile

TFA: trifluoroacetic acid

TBDMS: tert -butyldimethylsilyl

TBAF: tetrabutylammonium fluoride

DMF: dimethylformamide

DCM: dichloromethane

MeOH: methanol

THF: tetrahydrofuran

Example 1: Preparation of cyclized Ganciclovir

The starting compound is the compound of formula:

marketed as an antiviral drug under the name Ganciclovir.

¹ H NMR (400 MHz, DMSO) δ: 10.59 (s, 1H, NH), 7.79 (s, 1H, _imid H), 6.45 (s, 2H, NH _2), 5.42 ( s, 2H, H _{1 '} ), 4.58 (t, J = 5.4 Hz, 2H, OH), 3.57-3.51 (m, 1H, H _2' ), 3.44-3, 39 (m, 2H, H _{3 '} ), 3.30-3.27 (m, 2H, H _3' ) ppm

¹³ C NMR (100 MHz, DMSO) δ: 156.8 (C ₆ ), 153.8 (C ₂ ), 151.3 (C ₄ ), 137.6 (C ₈ ), 116.4 (C ₅ ) , 80.0 (C _{2 '} ), 71.5 (C _1' ), 60.8 (C _{3 '} ) ppm

Step 1 : Preparation of 8-bromoganciclovir

To a suspension of Ganciclovir (1 eq, 19 mmol, 5.0 g) in water (250 mL), was added with vigorous stirring an aqueous solution of dibroma (1.5 eq, 29 mmol, 1.5 mL). in three equal fractions in a period of 30 min.

The mixture was kept under stirring for an additional 30 min and a precipitate formed.

The solids were removed by filtration, washed with water (2 x 50 mL) and acetone (1 x 50 mL) and dried in vacuo to give a white solid (5.29 g, yield 83 %).

¹ H NMR (500 MHz, DMSO d6) δ: 10.71 (s, 1H, NH), 6.60 (s, 2H, NH _2), 5.40 (s, 2H, H _{1 '),} 4, 59 (t, J = 5.5Hz, 2H), 3.60 (m, 1H, H _{2 '} ), 3.45 (dd, J = 13.7, 6.1Hz, 2H, H _3' ) , 3.30 (dd, J = 13.7, 7.2 Hz 2H, H _{3 '} ) ppm

¹³ C NMR (110 MHz, DMSO) δ: 155.6 (C ₆ ), 154.1 (C ₂ ), 152.7 (C ₄ ), 120.9 (C ₈ ), 116.6 (C ₅ ) , 80.7 (C _{2 '} ), 72.0 (C _1' ), 60.8 (C _{3 '} ) ppm

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 334.0145; [M + H ⁺ ] _found : 334.0143

Step 2 : Preparation of 8-bromoganciclovir-diTBDMS

To a solution of 8-bromoganciclovir (1 eq, 1.5 mmol, 500 mg) in dry DMF was added imidazole (4 eq, 6.0 mmol, 410 mg) and the solution was stirred under argon until homogenized. Tert -butyldimethylsilyl chloride (3 eq., 4.5 mmol, 680 mg) was added and the mixture was stirred for 24 h.

The reaction mixture was then poured into cold water (40 mL) and the formed precipitate was removed by filtration and washed with water (1 x 15 mL).

The crude product was purified by flash chromatography (silica gel, DCM / MeOH, 100/0 to 90/10) to give the desired product as a white powder (830 mg, 98%).

¹ H NMR (500 MHz, DMSO d6) δ: 10.67 (s, 1H, NH), 6.54 (s, 2H, NH _2), 5.37 (s, 2H, H _{1 ')} 3, 71-3.67 (m, 1H, H _{2 '} ), 3.58 (dd, J = 10.7, 4.5Hz, 2H, H _3' ), 3.45 (dd, J = 10.7 , 5.6 Hz 2H, H _{3 '} ), 0.81 (s, 18H, C-CH ₃ ), -0.03 (s, 6H, Si-CH ₃ ), -0.04 (s, 6H, Si-CH ₃ ) ppm.

¹³ C NMR (110 MHz, DMSO d6) δ: 155.6 (C ₆ ), 154.2 (C ₂ ), 152.7 (C ₄ ), 120.8 (C ₈ ), 116.9 (C ₅ ), 80.4 (C _{2 '} ), 72.2 (C _1' ), 62.1 (C _{3 '} ), 25.8 (Si-C-CH ₃ ), 18.0 (Si-C), -5.5 (Si-CH ₃ ) ppm.

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 564.1860; [M + H ⁺ ] _found : 564.1857

Step 2 ' : Isolation of 8-bromoganciclovir-monoTBDMS

8-bromoganciclovir-monoTBDMS was isolated from the previous alcohol protection reaction of 8-bromoganciclovir using a defective silylating agent.

¹ H NMR (500 MHz, DMSO d6) δ: 10.69 (s, 1H, NH), 6.59 (s, 2H, NH _2), 5.38 (s, 2H, H _{1 '),} 4, 7 (t, J = 5.6Hz, 1H, OH), 3.69- 3.64 (m, 1H, H _{2 '} ), 3.56 (dd, J = 11.0, 4.4Hz, 1H, H _{3 '} ), 3.47-3.34 (m, 3H, H _3' , H _{4 '} ), 0.79 (s, 9H, C-CH ₃ ), -0.06 (s, 3H, Si-CH ₃ ), -0.07 (s, 3H, Si-CH ₃ ) ppm

¹³ C NMR (110 MHz, DMSO d6) δ: 155.6 (C ₆ ), 154.1 (C ₂ ), 152.6 (C ₄ ), 120.7 (C ₈ ), 116.7 (C ₅ ), 80.7 (C _{2 '} ), 72.1 (C _1' ), 62.7 (C _{3 '} ), 60.5 (C _4' ), 25.7 (Si-C-CH ₃ ), 17.9 (Si-C), -5.6 (Si-CH ₃ ) ppm

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 448.1010; [M + H ⁺ ] _found : 448.1011

Step 3 : Preparation of the racemic mixture of cis isomers of cyclized Ganciclovir-diTBDMS

8-Bromoganciclovir di-TBDMS (1 eq, 0.38 mmol, 217 mg) was suspended in freshly distilled anhydrous acetonitrile (55 mL) and previously flushed with argon for 40 min. The mixture was refluxed under argon until the base dissolved, then AIBN (2.5 eq, 0.56 mmol, 160 mg) and tributyltin hydride (2.5 eq, 0 , 96 mmol, 0.25 mL) were added and the solution was refluxed for 12 h. After cooling to room temperature, the solvents were removed in vacuo and the crude product was first purified by column chromatography on silica gel (DCM / MeOH 95/5, then 100% EtOAC). The mixture of cyclized and uncyclized products was then purified on preparative silica plates with the same eluents to give the cyclized product in the form of a white solid (28 mg, 15% yield).

¹ H NMR (500 MHz, DMSO d6) δ: 10.82 (s, 1H, NH), 6.72 (s, 2H, NH _2), 5.61 (d, J = 9.2 Hz, 1H, H _{1 '} ), 5.29 (d, J = 9.2 Hz, 1H, H ₁ '), 4.75 (d, J = 1.5 Hz, 1H, H _{3 '} ), 3.93-3 , 89 (m, 1H, H _{2 '} ), 3.87-3.80 (m, 2H, H _4' ), 0.87 (s, 9H, C-CH ₃ ), 0.81 (s, 9H , C-CH ₃ ), 0.18 (s, 3H, Si-CH ₃ ), 0.06 (s, 6H, Si-CH ₃ ), -0.08 (s, 3H, Si-CH ₃ ) ppm .

¹³ C NMR (110 MHz, DMSO d6) δ: 156.7 (C ₆ ), 154.0 (C ₂ ), 149.1 (C ₄ ), 142.3 (C ₈ ), 115.8 (C ₅ ), 79.3 (C _{2 '} ), 74.6 (C _1' ), 63.3 (C _{3 '} ), 61.7 (C _4' ), 25.8 (Si-C-CH ₃ ), 25.7 (Si-C-CH ₃ ), 18.0 (Si-C), 17.9 (Si-C), -4.2 (Si-CH ₃ ), -5.3 (Si-CH ₃ ), -5.4 (Si-CH ₃ ) ppm.

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 482.2613; [M + H ⁺ ] _found : 482.2611

Step 3 ' : Preparation of the racemic mixture of trans isomers of cyclized Ganciclovir-diTBDMS

The racemic mixture of trans isomers of cyclized Ganciclovir-diTBDMS was also isolated by chromatography on silica plates in very small amount (a few mg) in small amount during the previous reaction.

¹ H NMR (500 MHz, DMSO d6) δ: 10.76 (s, 1H, NH), 6.65 (s, 2H, NH _2), 5.42 (d, J = 9.2 Hz, 1H, H _{1 '} ), 5.37 (d, J = 9.2 Hz, 1H, H ₁ '), 4.77 (d, J = 8.2 Hz, 1H, H _{3 '} ), 3.85 (m , 1H, H _{2 '} ), 3.75 (m, 2H, H _4' ), 0.81 (s, 9H, C-CH ₃ ), 0.71 (s, 9H, C-CH ₃ ), 0 , 17 (s, 3H, Si-CH ₃ ), -0.00 (s, 6H, Si-CH ₃ ), -0.11 (s, 3H, Si-CH ₃ ) ppm.

¹³ C NMR (110 MHz, DMSO d6) δ: 156.6 (C ₆ ), 153.9 (C ₂ ), 149.3 (C ₄ ), 143.5 (C ₈ ), 116.0 (C ₅ ), 80.8 (C _{2 '} ), 73.9 (C _1' ), 63.3 (C _{3 '} ), 61.8 (C _4' ), 25.8 (Si-C-CH ₃ ), 25.7 (Si-C-CH ₃ ), 18.0 (Si-C), 17.9 (Si-C), -3.8 (Si-CH ₃ ), -5.3 (Si-CH ₃ ), -5.4 (Si-CH ₃ ) ppm

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 482.2613; [M + H ⁺ ] _found : 482.2618

Step 4 : Preparation of the racemic mixture of cis isomers of deprotected cyclized Ganciclovir

The racemic mixture of cis isomers of cyclized Ganciclovir-diTBDMS (1 eq, 0.064 mmol, 31 mg) was dissolved in the THF / TFA / H ₂ O 10/4/1 mixture (2 mL) at room temperature for 18 h . The solution was then quenched by the addition of MeOH (2 mL) and concentrated in vacuo 3 times.

The crude product was suspended in 2 mL of water and neutralized with aqueous NaHCO ₃ , then purified by reverse phase chromatography (Water / MeOH 9/1 to 7/3) to give the desired product (12.4 mg / 77%).

¹ H NMR (500 MHz, DMSO d6) δ: 10.73 (s, 1H, NH), 6.59 (s, 2H, NH _2), 5.67 (d, J = 6.1 Hz, 1H, OH), 5.56 (d, J = 8.3Hz, 1H, H _{1 '} ), 5.28 (d, J = 8.3Hz, 1H, H _1' ), 4.86 (t, J = 5.1Hz, 1H, OH), 4.54 (d, J = 5Hz, 1H, H _{3 '} ), 3.83 (m, 1H, H _2' ), 3 , 67-3.64 (m, 2H, H _{4 '} ) ppm.

¹³ C NMR (100 MHz, DMSO d6) δ: 156.7 (C ₆ ), 153.8 (C ₂ ), 148.9 (C ₄ ), 143.8 (C ₅ ), 115.7 (C ₈ ), 80.1 (C _{2 '} ), 74.6 (C _1' ), 61.5 (C _{3 '} ), 60.0 (C _4' ) ppm.

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 254.0884; [M + H ⁺ ] _found : 254.0885

Example 2: Preparation of cyclized Penciclovir

The starting compound is the compound of formula:

marketed as an antiviral drug under the name Penciclovir.

¹ H NMR (400 MHz, DMSO d6) δ: 10.49 (s, 1H, NH), 7.67 (s, 1H, _imid H), 6.40 (s, 2H, NH _2), 4.40 (t, J = 5.6Hz, 2H, OH) 3.98 (t , J = 7.2Hz, 2H, H _{1 '} ), 3.46-3.40 (m, 2H, H _4' ) 3.38-3.34 (m, 2H, H _{4 '} ), 1.71 (d, J = 14.5, 6.5Hz, 2H, H _2' ), 1.43 (m, 1H, H _{3 '} ) ppm.

¹³ C NMR (100 MHz, DMSO d6) δ: 157.3 (C ₆ ), 153.9 (C ₂ ), 151.36 (C ₄ ), 137.8 (C ₈ ), 117.0 (C ₅ ), 61.8 (C _{4 '} ), 41.5 (C _1' ), 41.2 (C _{3 '} ), 29.2 (C _2' ) ppm.

Step 1 : Preparation of 8-bromopenciclovir

To a suspension of Penciclovir (1 eq, 2.0 mmol, 500 mg) in water (25 mL), was added with vigorous stirring an aqueous solution of dibroma (1.5 eq, 3.0 mmol, 150 µL ) in three equal fractions in a period of 30 min.

The mixture was kept under stirring for an additional 30 min and a precipitate formed.

The solids were removed by filtration, washed with water (2 x 15 mL) and acetone (2 x 15 mL) and dried in vacuo to give a white solid (521 mg, 80% yield) .

¹ H NMR (400 MHz, DMSO d6) δ: 10.64 (s, 1H, NH), 6.56 (s, 2H, NH _2), 3.98 (t, J = 7.5 Hz, 2H, H _{1 '} ), 3.44 (dd, J = 10.4, 5.6 Hz, 2H, H _4' ), 3.35 (dd, J = 10.6, 5.5 Hz, 2H, H _{4 '} ), 1.68-1.62 (m, 2H, H _2' ), 1.52-1.46 (m, 1H, H _{3 '} ) ppm.

¹³ C NMR (100 MHz, DMSO d6) δ: 155.5 (C ₆ ), 153.8 (C ₂ ), 152.3 (C ₄ ), 120.6 (C ₈ ), 116.8 (C ₅ ), 61.4 (C _{4 '} ), 42.1 (C _1' ), 41.0 (C _{3 '} ), 28.4 (C _2' ) ppm.

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 332.0353; [M + H ⁺ ] _found : 332.0349

Step 2 : Preparation of 8-bromopenciclovir-diTBDMS

To a solution of 8-bromopenciclovir (1 eq, 0.9 mmol, 300 mg) in dry DMF (12 mL) was added imidazole (4 eq, 3.6 mmol, 250 mg) and the solution was stirred under argon until homogenized. Tert -butyldimethylsilyl chloride (3 eq., 2.7 mmol, 410 mg) was added and the orange mixture was stirred at room temperature for 24 h.

Cold water (20 mL) was then added to the reaction mixture and the formed precipitate was removed by filtration and washed with water (1 x 10 mL).

The crude product was purified by flash chromatography (silica gel, DCM / MeOH, 100/0 to 90/10) to give the desired product as a white powder (487 mg, 96%).

¹ H NMR (400 MHz, DMSO d6) δ: 10.69 (s, 1H, NH), 6.49 (s, 2H, NH _2), 3.97 (t, J = 7.2 Hz, 2H, H _{1 '} ), 3.57-3.49 (m, 4H, H _4' ), 1.71-1.66 (m, 2H, H _{2 '} ), 1.58-1.52 (m, 1H , H _{3 '} ), 0.84 (s, 18H, C-CH ₃ ), 0.0 (s, 12H, Si-CH ₃ ) ppm

¹³ C NMR (100 MHz, DMSO d6) δ: 155.5 (C ₆ ), 153.8 (C ₂ ), 152.3 (C ₄ ), 120.3 (C ₈ ), 116.9 (C ₅ ), 61.9 (C _{4 '} ) _, 41.9 (C _1' ), 40.7 (C _{3 '} ), 27.1 (C _2' ), 25.7 (Si-C-CH ₃ ), 17.8 (Si-C), -5.5 (Si-CH ₃ ) ppm

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 562.2067; [M + H ⁺ ] _found : 562.2060

Step 3 : Preparation of the racemic mixture of cis isomers of cyclized Penciclovir-diTBDMS

8-Bromopenciclovir-diTBDMS (1 eq, 0.53 mmol, 300 mg) was suspended in freshly distilled anhydrous acetonitrile (70 mL) and previously flushed with argon for 40 min. The mixture was refluxed under argon until the base dissolved, then AIBN (2.5 eq, 1.35 mmol, 220 mg) and tributyltin hydride (2.5 eq, 1 , 35 mmol, 0.36 mL) were added and the solution was refluxed for 12 h. After cooling to room temperature, the solvents were removed in vacuo and the crude product was first purified by column chromatography on silica gel (DCM / MeOH 95/5, then 100% EtOAC). The mixture of cyclized and uncyclized products was then purified by preparative TLC with the same eluents to give the cyclized product as a white solid (61 mg, 23% yield).

¹ H NMR (400 MHz, DMSO d6) δ: 10.56 (s, 1H, NH), 6.48 (s, 2H, NH _2), 4.84 (d, J = 2.0 Hz, 1H, H _{4 '} ), 4.02 (dd, J = 12.3, 5.2 Hz, 1H, H _1' ), 3.75-3.59 (m, 3H, H _{1 '} H _5' ), 2 , 02-1.85 (m, 2H, H _{2 '} ), 1.84-1.76 (m, 1H, H _3' ), 0.88 (s, 9H, C-CH ₃ ), 0.79 (s, 9H, C-CH ₃ ), 0.19 (s, 3H, Si-CH ₃ ), 0.05 (s, 6H, Si-C-CH ₃ ), -0.16 (s, 3H, Si-CH ₃ ) ppm.

¹³ C NMR (100 MHz, CDCl ₃ ) δ: 159.5 (C ₆ ), 153.6 (C ₂ ), 152.2 (C ₄ ), 147.7 (C ₈ ), 116.0 (C ₅ ), 63.6 (C _{4 '} ) _, 63.3 (C _5' ) _, 42.95 (C _{3 '} ), 41.5 (C _1' ), 29.8 (C _{2 '} ), 26.1 (Si-C-CH ₃ ), 26.0 (Si-C-CH ₃ ), 18.6 (Si-C), 18.5 (Si-C), -4.3 (Si-CH ₃ ), -5.0 (Si-CH ₃ ), -5.1 (Si-CH ₃ ), -5.2 (Si-CH ₃ ) ppm.

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 480.2821; [M + H ⁺ ] _Found : 480.2825.

Step 4 : Preparation of the racemic mixture of cis isomers of cyclized Penciclovir

The racemic mixture of cis isomers of cyclized Penciclovir-diTBDMS (1 eq, 0.021 mmol, 10 mg) and 2 drops of pyridine were dissolved in THF (0.6 mL) before addition of an HF / solution. pyridine (30 μL) and the mixture was stirred at room temperature for 18 h. MeOH (2 mL) was added and the solution was concentrated in vacuo 3 times before being neutralized with NaHCO ₃ .

The crude product was suspended in 2 mL of water and neutralized with aqueous NaHCO ₃ , then purified by reverse phase chromatography (Water / MeOH 100/0 to 70/30) to give the desired product (5 mg, yield quantitative).

¹ H NMR (400 MHz, DMSO d6) δ: 10.48 (s, 1H, NH), 6.40 (s, 2H, NH _2), 5.41 (d, J = 4.6 Hz, 1H, OH) 4.64 (d, J = 2.0Hz, 1H, H _{4 '} ), 4.56 (t, J = 4.5Hz, 1H, OH), 4.00 (dd, J = 12, 2, 5.1Hz, 1H, H _{1 '} ), 3.67-3.55 (m, 2H, H _1', H _{5 '} ), 3.43-3.40 (m, 1H, H _5' ), 1.94-1.81 (m, 3H, H _{2 '} , H _3' ) ppm.

¹³ C NMR (100 MHz, DMSO d6) δ: 156.8 (C ₆ ), 153.4 (C ₂ ), 150.9 (C ₄ ), 147.1 (C ₈ ), 115.8 (C ₅ ), 61.7 (C _{4 '} ) _, 61.4 (C _5' ) _, 41.1 (C _{3 '} ), 41.0 (C _1' ), 18.7 (C _{2 '} ) ppm.

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 252.1091; [M + H ⁺ ] _found : 252.1090

Example 3: Preparation of N-benzoyl cyclodeoxyganciclovir and cyclodeoxyganciclovir

General summary diagram:

Step 1 : Preparation of ganciclovir-diTBDMS

To a suspension of ganciclovir (1 eq., 15.7 mmol, 4.00 g) in anhydrous DMF (150 mL) was added imidazole (44.3 mmol, 3.02 g) and the solution. was stirred under argon until homogenized. Tert -butyldimethylsilyl chloride (3.01 eq., 47.3 mmol, 7.1 g) was added and the mixture was stirred for 14h.

The reaction mixture was then poured into cold water (500 mL) and the formed precipitate was removed by filtration and washed with water (3 x 20 mL). After drying, 6.79 g of disilylated ganciclovir were obtained (14.04 mmol, 89%).

The product thus obtained being sufficiently pure, it was used in the next step without further purification.

¹ H NMR (400 MHz, DMSO d6) δ: 10.61 (s, 1H, NH), 7.82 (s, 1H, H _8), 6.46 (s, 2H, NH _2), 5, 44 (s, 2H, H ₁ ^, ), 3.68 (m, 1H, H ₂ ^, ), 3.61 (m, 2H, H ₃ ^' or H ₃ ^” ), 3.48 (m, 2H, H ₃ ^' or H ₃ ^” ), 0.85 (s, 18H, C-CH ₃ ), 0.00 (s, 12H, Si-CH ₃ ).

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 484.2772; [M + H ⁺ ] _Found : 484.2770.

Step 2 : Preparation of N-benzoyl ganciclovir-diTBDMS

Step 2A : Benzoylation

To a solution of ganciclovir-diTBDMS (1 eq, 13.4 mmol, 6.5 g) in anhydrous pyridine (180 mL) was added dropwise benzoyl chloride (4 eq, 146 mmol, 17 mL) and the solution was stirred under argon for 24h.

After adding water (7 mL), the reaction mixture was concentrated then DCM was added (150 mL). The organic phase was then washed three times with water and then dried over magnesium sulfate MgSO ₄ .

After evaporation under reduced pressure, the residue was taken up in dry toluene and the mixture was subjected to evaporation under reduced pressure to remove residual water, then dried. A mixture of monobenzoyl ganciclovir-diTBDMS and dibenzoyl ganciclovir-diTBDMS was thus obtained (7.2 g).

Step 2B : Basic treatment

The mixture of ganciclovir-diTBDMS monobenzoyl and dibenzoyl ganciclovir-diTBDMS obtained previously was dissolved in dioxane (65 mL) then an aqueous solution of NaOH was added (1.5 g in 20 mL). The mixture was stirred at room temperature so as to convert the dibenzoyl derivative into monobenzoyl derivative. After 3 h the pH was brought to 6.5 by slow addition of a 1M aqueous HCl solution. The reaction mixture was then poured into cold water (250 mL) and the precipitate formed was removed by filtration and washed with water (3 x 20 mL) and then dried.

Step 2C : Desilylation, obtaining N-benzoyl ganciclovir

The mixture obtained above was dissolved in anhydrous THF (40 mL) and a solution of 1M tetrabutyl ammonium fluoride was added (40 mL, 40 mmol). The solution obtained was stirred for 24 h then the mixture was evaporated to dryness. After adding DCM and water, the precipitate formed was removed by filtration and washed with ethyl ether (3 x 30 mL). The dried solid was then recrystallized from methanol to obtain 1.2 g of N-benzoyl ganciclovir (25%)

¹ H NMR (400 MHz, DMSO d6) δ: 11.94 (s, 2H, 2 NH), 8.14 (s, 1H, H _8), 8.05 (m, 2H, Bz), 7.65 (m, 1H, Bz), 7.54 (m, 2H, Bz), 5.61 (s, 2H, H _{1 '} ), 4.62 (t, 2H, J = 5.6Hz, OH), 3.60 (m, 1H, H _{2 '} ), 3.44 (m, 1H, H _3' ), 2.91 (m, 1H, H _{4 '} ) ppm.

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 360.1302; [M + H ⁺ ] _Found : 360.1300.

Step 3 : Preparation of phenylthio N-benzoyl deoxyganciclovir

To a solution of N-benzoyl deoxyganciclovir (1 eq., 1.31 mmol, 470 mg) in anhydrous DMF (7.2 mL), diphenyl disulfide (1.5 eq., 1.96 mmol, 428 mg ) and tributylphosphine (1.5 eq., 2.0 mmol, 483 microL) were added. The resulting solution was then stirred for 24 h under an argon atmosphere. After evaporation to dryness, the residue was chromatographed on silica gel to obtain the phenylthio N-benzoyl deoxyganciclovir as a white powder (250 mg, 42%).

¹ H NMR (400 MHz, DMSO d6) δ: 12.26 (s, 1H, NH), 11.90 (s, 1H, NH), 8.09 (s, 1H, H _8), 8.02 ( m, 2H, Bz), Bz), 7.68 (m, 1H, Bz), 7.56 (m, 2H, Bz), 7.18 (m, 2H, SPh), 7.10 (m, 2H , SPh), 7.05 (m, 1H, SPh), 5.58 (dd, 2H, J = 11.2 Hz and 17.2 Hz, H _{1 '} ), 4.93 (t, 1H, J = 5.2 Hz, OH), 3.82 (m, 1H, H _{2 '} ), 3.54 (m, 1H, H _4' ), 3.47 (m, 1H, H _{4 '} ), 3.14 (dd, 1H, J = 4.4Hz & 14Hz, H _{3 '} ), 2.84 (m, 1H, H _3' ).

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 360.1300; [M + H ⁺ ] _Found : 360.1302.

Step 4 : Cyclization of phenylthio N-benzoyl deoxyganciclovir, obtaining N-benzoyl cyclodeoxyganciclovir

Phenylthio N-benzoyl deoxyganciclovir (1 eq., 0.233 mmol, 105 mg) was suspended in acetonitrile (263 mL) freshly distilled and previously dried over molecular sieve. The mixture was heated at reflux until complete dissolution then allowed to cool to room temperature. Triethylphosphite (10.5 eq., 2.40 mmol, 411 microL) was added and the mixture was deaerated by bubbling argon for 40 min then irradiated at 254 nm for 8 h in a photoreactor fitted with a lamp. high pressure mercury 150 W (Hanau TQ150). After evaporating the acetonitrile to dryness, the residue was chromatographed on silica gel to obtain N-benzoyl cyclodeoxyganciclovir as a white powder (50 mg, 63%). A fraction of the starting material was also recovered (27 mg, 0.060 mmol).

¹ H NMR (400 MHz, DMSO d6) δ: 12.32 (s, 1H, NH), 12.04 (s, 1H, NH), 8.06 (m, 2H, Bz), 7.68 (m , 1H, Bz), 7.56 (m, 2H, Bz), 5.64 (m, 2H, H _{1 '} ), 5.07 (t, 1H, J = 5.6Hz, OH), 4, 11 (m, 1H, H _{2 '} ), 3.64 (t, 2H, d = 5.2 Hz, H _4' ), 2.98 (m, 1H, H _{3 '} ), 2.86 (m, 1H, H _{3 '} ).

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 452.1387; [M + H ⁺ ] _Found : 452.1385.

Step 5 : Debenzoylation of N-benzoyl cyclodeoxyganciclovir, obtaining cyclodeoxyganciclovir

The N-benzoyl cyclodeoxyganciclovir obtained above (1 eq, 0.017 mmol, 4 mg) is suspended in anhydrous ethanol (1 mL) and 25% ammonia (1 mL). The flask containing the reaction mixture is stoppered with a septum and then it is heated at 65 ° C. for 15 h. The resulting mixture is then evaporated to dryness and the residue is washed with ether and dried under vacuum. Cyclodeoxyganciclovir is thus obtained in the form of a white powder (2 mg, 72%).

¹ H NMR (400 MHz, DMSO d6) δ: 10.53 (s, 1H, NH), 6.42 (s, 2H, NH ₂ ), 5.58 (d, J = 8Hz, H ₁ ^' ), 5.37 (d, J = 8Hz, H ₁ ^' ), 5.01 (s, 1H, OH), 4.01 (m, 1H, H ₂ ^' ), 3.60 (m, 2H, H ₃ ^' ), 2.88 (m, 1H, H ₄ ^' ), 2.77 (m, 1H, H ₄ ^' ).

HRMS (ESI ⁺ ): [M + H ⁺ ] _Calculated : 238.0935; [M + H ⁺ ] _Found : 238.0935.

Example 4: Demonstration of pharmacological properties

Cells and viruses

Human Embryonic Lung Fibroblasts (HEL) [HEL 299 (ATCC ^R CCL-137 ^TM )] and Crandell Rees feline kidney cell line, CRFK (ATCC ^R CCL-94 ^TM ) were obtained from ATCC.

A KOS strain of herpes simplex virus type 1 (HSV-1) (ATCC ^R VR-1493 ^TM ), the thymidine kinase (TK ^- ) deficient KOS HSV-1 strain was selected in vitro under increasing concentrations. ACV, herpes simplex virus type 2 (HSV-2) strain G (ATCC ^R VR-734 ^TM ); varicella zoster virus (VZV) strain Oka (ATCC VR-795), TK strain 07-1 ^- VZV (supplied by Shiro Shigeta, Fukushima Medical Center, Japan); human cytomegalovirus (HCMV) (ATCC ^R VR-538 ^TM ) and Davis (ATCC ^R VR-807 ^TM ) strains AD-169, feline herpes virus strain C-27 (ATCC ^R VR-636 ^TM ) were used at the Rega Institute for Medical Research.

The compounds were evaluated against various human herpes viruses, including the KOS strain of HSV-1, TK ^- HSV-1 KOS AVC-R, the G strain of HSV-2, the Oka strain and VZV strain 07-1, HCMV AD-169 and Davis strains in HEL cells and against feline herpes virus in feline kidney cells (CRFK).

Confluent cell cultures in 96-well microtiter plates were inoculated with 100 CCID ₅₀ of virus (1 CCID ₅₀ being the viral dose to infect 50% of cell cultures) or with 50 plaque forming units (PFU) (VZV) and cell cultures were incubated in the presence of varying concentrations of test compounds. Viral cytopathogenicity or plaque formation (VZV) was recorded as soon as he or she reached the point of completion in control virus-infected cell cultures that were not treated with the test compounds. Antiviral activity was expressed as an EC ₅₀ or compound concentration required to reduce virus-induced cytopathogenicity or viral plaque formation by 50%. The cytotoxicity of the test compounds was expressed as the minimum cytotoxic concentration (MCC) or the concentration of the compound which caused a microscopically detectable alteration in cell morphology. Alternatively, the cytostatic activity of the test compounds was measured based on the inhibition of cell growth. HEL cells were seeded at a rate of 5 x 10 ³ cells / well in 96 well microtiter plates and allowed to proliferate for 24 hours. Then, a medium comprising different concentrations of the test compounds was added. After 3 days of incubation at 37 ° C, the cell count was determined with a Coulter counter. The cytostatic concentration was calculated as CC ₅₀ , or the concentration of compound required to reduce cell proliferation by 50% relative to the number of cells in untreated controls.

Evaluation of the antiviral activity of the racemic mixture of enantiomers:

The results of the anti-viral activity of a racemic mixture whose formulas are indicated above are given in Table 2.

Sample 1 and Sample 2 correspond to this racemic mixture obtained during two separate syntheses

Compound	Minimum cytotoxic concentration (a)	Cell growth (CC50) (b)	EC 50 µM
			Herpes simplex virus type-1 (KOS) (c)	Herpes simplex virus type-2 (G) (d)	Herpes simplex virus type-1 TK-KOS (ACV-R) (c)	Feline Herpes Virus (d)	Strain TK + VZV OKA (e)	Strain TK- VZV 07-1 (e)
Sample 1	> 10		1.2	0.8	8	9.5	7.1	37
Sample 1	> 10		0.4	0.4	18	12.2	10.5	79
Sample 2	> 100	64.5	1.2	1.2	> 100		28	20
Sample 2	> 100		1.1	0.8	> 100
Aciclovir			1	0.4	> 90

1. Determined by measuring cell viability with the formazan colorimetric test (MTS).
2. Cytotoxic concentration in µM leading to a reduction in cell growth by 50%.
3. Concentration in μM leading to the reduction of cytopathogenicity induced by the virus by 50% in cultures of HEL cells.
4. Concentration in μM leading to a reduction of the cytopathogenicity induced by the virus by 50% in cultures of CRFK cells (Crandell-Rees Feline Kidney cells).
5. Activity of the compound against varicella zoster virus (varicella zoster, VZV) in human lung embryo HEL cells.

Evaluation of the antiviral activity of cyclodeoxyganciclovir

The results of the anti-viral activity of cyclodeoxyganciclovir, the formula of which is indicated above, are given in Table 3.

Compound	Cell morphology (a)	Cell growth (CC50) (b)	EC 50 µM
			Herpes simplex virus type-1 (KOS) (c)	Herpes simplex virus type-2 (G) (d)	Herpes simplex virus type-1 TK-KOS (rACV) (c)	Strain TK + VZV OKA (e)	Strain TK- VZV 07-1 (e)
Sample 1	> 84 > 84	> 422 > 422	11.3 5.1	25 32	> 84 > 84	> 84 > 84	> 84 > 84
Aciclovir	> 444 > 444	> 444 > 444	0.14 0.26	0.18 0.31	56 89	8.5 6.4	66 42

1. Minimum concentration causing alteration of morphology detectable under a microscope
2. Cytotoxic concentration in µM leading to a reduction in cell growth by 50%.
3. Concentration in μM leading to the reduction of cytopathogenicity induced by the virus by 50% in cultures of HEL cells.
4. Concentration in μM leading to a reduction of the cytopathogenicity induced by the virus by 50% in cultures of CRFK cells (Crandell-Rees Feline Kidney cells).
5. Activity of the compound against varicella zoster virus (varicella zoster, VZV) in human lung embryo HEL cells.

Claims (11)

1. - Compound of general formula (I):
   

   

   
   (I)
   or a pharmaceutically acceptable enantiomer, tautomer, salt, solvate or prodrug thereof, or a mixture thereof,
   general formula (I) in which:

   • X represents O or CH ₂ ;
   • R ₁ represents: H, OH, NH ₂ ;
   • R ₂ represents: H, NH ₂ , -NH-benzoyl, OH, Cl;
   • R ₃ represents H;
   • R ₄ represents H; OH ; or OR ₆ where R ₆ represents:

   

   with R ' ₆ representing C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl or alternatively -CHR-NH ₂ , the latter representing the residue of a natural α-amino acid; R ₆ may also represent -SiR ₇ R ₈ R ₉ , where R ₇ , R ₈ and R ₉ each independently represent C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl; or

   • R ₃ and R ₄ together with the carbon atom to which they are attached represent

   

   ;

   • R ₅ represents:

   • OH ;
   • -OSiR ₁₀ R ₁₁ R ₁₂ , wherein R ₁₀ , R ₁₁ and R ₁₂ each independently represent C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl;

   • 
     , wherein R ₁₃ and R ₁₄ each independently represent H, C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl;

   • 
     , where n is 0 or 1 and R ₁₅ and R ₁₆ each independently represent H, C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl;

   • 
     , wherein R ₁₇ , R ₁₈ and R ₁₉ each independently represent H, C ₁ -C ₆ alkyl or C ₅ -C ₁₂ aryl;
   • -OC (O) R ₂₀ , where R ₂₀ represents C ₁ -C ₆ alkyl, C ₅ -C ₁₂ aryl or alternatively -CHR'-NH ₂ , the latter representing the residue of a natural α-amino acid;

   the alkyl and aryl radicals falling within the definition of R ' ₆ , R ₇ to R ₂₀ possibly being substituted,
   the compounds of general formula (I), their enantiomers, tautomers, pharmaceutically acceptable salts, solvates or prodrugs or mixtures for which R ₁ represents OH being represented in said formula (I) in their tautomeric form:
   

   
2. - Compound according to claim 1, or enantiomer, tautomer, salt, solvate or pharmaceutically acceptable prodrug of this compound, or a mixture of these, characterized in that, in formula (I):

   • R ₁ represents OH and R ₂ represents NH ₂ ; or
   • R ₁ represents NH ₂ and R ₂ represents H or Cl.
3. - Compound according to claim 2, or enantiomer, tautomer, salt, solvate or pharmaceutically acceptable prodrug of this compound, or a mixture of these, characterized in that, in formula I:

   • R ₁ represents OH, R ₂ represents NH ₂ , R ₃ represents H and R ₄ represents H or OH, or R ₃ and R ₄ together with the carbon atom to which they are attached represent

   

   .
4. - Compound according to claim 3, or enantiomer, tautomer, salt, solvate or pharmaceutically acceptable prodrug of this compound, or a mixture of these, characterized in that R ₅ represents OH.
5. - Compound according to claim 1, characterized in that it consists of a cis compound of formula:
   

   

   
   or
   

   

   
   or in a trans compound of formula:
   

   

   
   or
   

   

   
   or mixtures thereof, R ₁ , R ₂ , R ₅ and X being as defined in claim 1.
6. - Compound according to claim 1, characterized in that it consists of a compound of formula:
   

   

   
   or
   

   

   
   or
   

   

   .
7. - Pharmaceutical composition comprising at least one compound of general formula (I) as defined in one of claims 1 to 6 or an enantiomer, a tautomer, a salt, a solvate or a pharmaceutically acceptable prodrug of this compound or a mixture thereof and at least one pharmaceutically acceptable carrier.
8. - A compound according to one of claims 1 to 6 or a pharmaceutical composition according to claim 7 for use as a medicament.
9. - A compound or pharmaceutical composition according to claim 8 for use in the treatment of a disease or disorder caused by a virus.
10. - A compound or pharmaceutical composition according to claim 9, wherein the virus is a virus of the herpes family.
11. - Compound or pharmaceutical composition according to claim 10, wherein the virus is a virus of the herpes family chosen from: Herpes Simplex virus type 1 (HSV-1), Herpes Simplex virus type 2 (HSV- 2), Feline Herpes Virus and Varicella Zoster Virus (VZV).