1- -5-fluorouracils

Therapeutic Function Cancer chemotherapy Chemical Name 5-fluoro-2,4(1H,3H)-pyrimidinedione Common Name 5-fluorouracil Structural Formula h 

Trade Name Manufacturer Country Year Intro  

S-Methylisothiouronium sulfate Hydrogen chloride Sodium methoxide  

At the end of this time the crystalline precipitate which had formed was filtered off with suction, washed with diethyl ether, and dried in a vacuum desiccator. The product comprised essentially the potassium enolate of ethyl fluoromalonaldehydate (alternative nomen-ciature, the potassium salt of fluoromalonaldehydic acid ethyl ester). 

A mixture of 103.6 grams (0,6 mol) of the freshly prepared potassium enolate of ethyl fluoromalonaldehydate, 83.4 grams (0.3 mol) of S-methylisothiouronium sulfate and 32.5 grams (0.6 mol) of sodium methoxide was refluxed with stirring in 1,500 ml of absolute methanol. At first the reactants dissolved to a great extent, but very shortly thereafter precipitation occurred. The reaction mixture was refluxed for 2 hours and at the end of this time was evaporated to dryness in vacuo. The residue was treated with 280 ml of water incomplete dissolution was observed. 

A solution of 10.0 grams of purified S-methyl ether of 2-thio-5-fluorouracil, MP 230° to 237°C, in 150 ml of concentrated aqueous hydrochloric acid (containing approximately 37% by weight HCI) was refluxed under nitrogen for 4 hours. The reaction mixture was then evaporated in vacuo. The crystalline brownish residue was recrystallized from water. The resulting recrystallized product was further purified by sublimation in vacuo at 190° to 200°C (bath temperature)/0.1 mm pressure. There was obtained 5-fluorouracil, in the form of colorless or pinkish-tan crystals, MP 282° to 283°C (with decomposition). 

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C4H4N2O2. Colourless crystalline powder, turning brown at 280 C and melting at 338 C (decomp.). Uracil is a constituent of ribose nucleic acid. Used as a diuretic and derivatives have pharmaceutical importance. 5-Fluorouracil is used in cancer treatment. 

Fluorouracil is one component of a mixture of three drugs used in breast cancer chemotherapy What is its stmcture" ... 

Fluorinated Heterocyclic Compounds. HeterocycHc compounds containing the CF group are prepared by methods similar to those used in the fluorination of aHphatic compounds. The direct action of fluorine on uracil yields the cancer chemotherapy agent, 5-fluorouracil [51-21-8] as one special example of a selective fluorination on a commercial scale (25). 

Fluoropyrknidine derivatives are of tremendous importance in cancer chemotherapy, eg, 5-fluorouracil [51-21-8] (5-FU). The original 5-fluorouracil process featured a multistep low yield route based on ethyl fluoroacetate (451). Direct fluorination (fluorine) of uracil [66-22-8] gives high yields of 5-FU (452—455). This process has now been commercialized. 

Tetrafluoropyrimidine was converted to the antiaeoplastic 5-fluorouracil (5-FU) by a novel process based on the sequence partial exchange chlorination (61% yield), selective hydrogenolysis ia triethylamine (71% yield) and hydrolysis (85—93% yield) (464). 

Chemotherapeutic agents are grouped by cytotoxic mechanism. The alkylating agents, such as cyclophosphamide [50-18-0] and melphalan [148-82-3] interfere with normal cellular activity by alkylation deoxyribonucleic acid (DNA). Antimetabohtes, interfering with complex metaboHc pathways in the cell, include methotrexate [59-05-2] 5-fluorouracil [51-21-8] and cytosine arabinoside hydrochloride [69-74-9]. Antibiotics such as bleomycin [11056-06-7] and doxombicin [23214-92-8] h.a.ve been used, as have the plant alkaloids vincristine [57-22-7] and vinblastine [865-21-4]. 

With the aid of cytosine permease, flucytosine reaches the fungal cell where it is converted by cytosine deaminase into 5-fluorouracil [51-21-8]. Cytosine deaminase is not present in the host, which explains the low toxicity of 5-FC. 5-Fluorouracil is then phosphorylated and incorporated into RNA and may also be converted into 5-fluorodeoxyuridine monophosphate, which is a potent and specific inhibitor of thymidylate synthetase. As a result, no more thymidine nucleotides are formed, which in turn leads to a disturbance of the DNA-synthesis. These effects produce an inhibition of the protein synthesis and cell repHcation (1,23,24). 5-Fluorouracil caimot be used as an antimycotic. It is poorly absorbed by the fungus to begin with and is also toxic for mammalian cells. 

Uracil is used more effectively, in nucleic acid synthesis within a rat hepatoma than in normal liver. This observation appears to have stimulated the synthesis of 5-fluorouracil (1027) as an antimetabolite mainly because the introduction of a fluorine atom involves a minimal increase in size. In the event, 5-fluorouracil did prove to have antineoplastic activity and it is now a valuable drug for treatment of tumors of the breast, colon or rectum, and to a lesser extent, gastric, hepatic, pancreatic, uterine, ovarian and bladder carcinomas. As with other drugs which interfere with DNA synthesis, the therapeutic index is quite low and great care is required during treatment (69MI21301). 

Selective fluonnation in polar solvents has proved commercially successful in the synthesis of 5 fluorouracil and its pyrimidine relatives, an extensive subject that will be discussed in another section Selective fluonnation of enolates [47], enols [48], and silyl enol ethers [49] resulted in preparation of a/phn-fluoro ketones, fieto-diketones, heta-ketoesters, and aldehydes The reactions of fluorine with these functionalities is most probably an addition to the ene followed by elimination of fluonde ion or hydrogen fluoride rather than a simple substitution In a similar vein, selective fluonnation of pyridmes to give 2-fluoropyridines was shown to proceed through pyridine difluondes [50]... 

Fluorouracil can be produced by a variety of positive fluorine reagents as well as elemental fluorine (Table 1, entry 11)... 

A landmark scientific breakthrough resulted from the synthesis and metabohc studies of 5-fluorouracil (5) (fl ura or 5-FU), 5-fluoroorotic acid ( f) (fl oro), and 5-fluorocytosine (7) (fl cyt) by Heideiberger and co-workers [2] Several excellent recent reviews are available on this important field [9, 23, 24, 25, 26 ]. 

The following biochemically related F-NMR studies ot structure or tunebon have been published nucleic acid components (mainly 5-fluorouracil) [86... 

Interest contmues in prodrugs of 5-fluorouracil (5-FU) Doxifluridine (8) was recently mtroduced and appears to be more potent and less toxic than 5 FU [10 Flutamide (9) and nilutamide (/O) are both available for the treatment of prostatic cancer [//, 12]... 

Lethal drug interactions of new antiviral, sorivudin [l-(3-D-arabinofuranosyl-( )-5-(2-bromvinyl)uracil], with anticancer prodrugs of 5-fluorouracil structure 97YZ910. 

An amount of enzyme preparation equivalent to 900 mg of wet cells was made up to 25 ml with the above potassium phosphate buffer solution. 150 mg (1.15 mmol) of 5-fluorouracil and 1.0 gram of thymidine (4.12 mmol) were dissolved in 15 ml of the above potassium phosphate buffer solution. The mixture was incubated at 37°C for 18 hours. After this time, enzyme action was stopped by the addition of four volumes of acetone and one volume of peroxide-free diethyl ether. The precipitated solids were removed by filtration, and the filtrate was evaporated under nitrogen at reduced pressure until substantially all volatile organic solvent had been removed. About 20 ml of aqueous solution, essentially free of organic solvent, remained. This solution was diluted to 100 ml with distilled water. 

The preparation of 5-fluorouracil is given under "Fluorouracil." As described in U.S. Patent 3,040,026, 5-fluorouracil is then subjected to the following steps to give flucytosine. 

Chlorotrifluoroethylene was converted in one step using nBuLi to dieth-ylfluoromalonate, which was a useful precursor for 5-fluorouracil (84CL1573). Fluorinated pyrimidinones can also be obtained from a,fi-unsaturated carboxylic acid derivatives prepared from 1-phosphonyloxy-perfluoroalkyl-l-alkenephosphonates (86TL2879). 

Reaction of tetrafluoropyrimidine with anhydrous HC1 set up an equilibrium in which the outcome was determined by the reaction conditions. It allowed the isolation of 2,4,6-trichloro-5-fluoropyrimidine, an isomer not accessible by KF exchange. Hydrogenolysis and hydrolysis of the 2,5-difluoroisomer provided a convenient route to 5-fluorouracil [89JFC(45)417],... 

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