Abstract:
Substituted phenyl and naphthyl and 9-oxofluoren-4-yl esters of PGF 2  α, 15-alkyl-PGF 2  α, and 15(R)-15-alkyl-PGF 2  α, and their recemic forms, and processes for producing them are disclosed. The products are useful for the same pharamacological and medical purposes as PGF 2  α, 15-alkyl-PGF 2  α, and 15(R)-15-alkyl-PGF 2  α, and are also useful as a means for obtaining highly purified PGF 2  α, 15-alkyl-PGF 2  α, and 15(R)-15-alkyl-PGF 2  α products.

Description:
This is a division of application Ser. No. 431,758, filed Jan. 8, 1974. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to novel ester derivatives of prostaglandin F 2  α (hereinafter identified as PGF 2  α), 15-alkyl-PGF 2  α, 15(R)-15-alkyl-PGF 2  α, and their racemic forms, and to processes for producing them. 
     PGF 2  α is represented by the formula: ##SPC1## 
     A systematic name for PGF 2  α is 7-{3α,5α-dihydroxy-2β-[(3S)-3-hydroxy-trans-1-octenyl]-1.alpha.-cyclopentyl}-cis-5-heptenoic acid. PGF 2  α is known to be useful for a variety of pharmacological and medical purposes, for example labor induction and abortion in pregnant animals, including humans, menstrual regulation in both pregnant and non-pregnant animals, including humans, and reduction and control of gastric secretion. See Bergstrom et al., Pharmacol. Rev. 20, 1 (1968) and references cited therein. As to racemic PGF 2  α, see for example E. S. Corey et al., J. Am. Chem. Soc., 91, 5675 (1969). 
     The 15-alkyl-PGF 2  α analog and its 15(R) epimer are represented by the formula: ##SPC2## 
     Wherein Y&#39; is ##EQU1## following the usual convention wherein broken line attachment of hydroxy to the side chain at carbon 15 indicates the natural or S configuration and solid line attachment of hydroxy indicates the epi or R configuration. See for example Nugteren et al., Nature 212, 38 (1966) and Cahn, J. Chem. Ed. 41, 116 (1964). The 15-alkyl- and 15(R)-15-alkyl-PGF 2  α analogs in their optically active and racemic forms are known. See for example U.S. Pat. No. 3,728,382. These analogs are also useful for the above-described pharmacological purposes. 
     Esters of the above compounds are known, wherein the hydrogen atom of the carboxyl group is replaced by a hydrocarbyl or substituted hydrocarbyl group. Among these are the methyl ester of PGF 2  α (B. Samuelsson, J. Biol. Chem. 238, 3229 (1963)), the methyl ester of racemic PGF 2  α (E. J. Corey et al., J. Am. Chem. Soc. 91, 5675 (1969)), the methyl ester of 15-methyl-PGF 2  α (E. W. Yankee et al., J. Am. Chem. Soc. 94, 3651 (1972)), the phenyl, alkyl-phenyl, and 1-naphthyl esters of PGF 2  α (British Spec. 1,040,544, see Derwent Farmdoc. No. 22,599), and the α-naphthyl ester of PGF 2  α (Belgian Patent 775,106, see Derwent Farmdoc No. 33705T). 
     SUMMARY OF THE INVENTION 
     It is a purpose of this invention to provide novel ester derivatives of prostaglandin PGF 2  α, 15-alkyl-PGF 2  α, 15(R)-15-alkyl-PGF 2  α, and their racemic forms. It is a further purpose to provide such esters derived from substituted phenols and naphthols, and hydroxyfluorenone. 
     It is a further purpose to provide such esters in a free-flowing crystalline form. It is still a further purpose to provide novel processes for preparing these esters. 
     The presently described esters include compounds represented by the generic formula: ##SPC3## 
     wherein Z is the substituted phenyl or naphthyl group or fluorenone as defined immediately below, and Y is ##EQU2## i.e. esters of PGF 2  α, 15-methyl-PGF 2  α, 15(R)-15-methyl-PGF 2  α, 15-ethyl-PGF 2  α and 15(R)-15-ethyl-PGF 2  α; and also the racemic compounds represented by each respective formula and the mirror image thereof; Z being represented by ##SPC4## 
     For example, PGF 2  α, p-acetamidophenyl ester, is represented by formula III wherein Y is ##EQU3## and Z is A, i.e. ##SPC5## 
     and is conveniently identified herein as the PGF 2  α ester of formula III-A. Racemic compounds are designated by the prefix racemic or dl; when that prefix is absent, the intent is to designate an optically active compound. Racemic 15-methyl-PGF 2  α, p-benzamidophenyl ester, corresponds to formula III wherein Y is ##EQU4## and Z is B, i.e. ##SPC6## 
     including of course not only the optically active isomer represented by formula III but also its mirror image. 
     The novel formula-III compounds and corresponding racemic compounds of this invention are each useful for the same purposes as described above for PGF 2  α and are used for those purposes in the same manner known in the art, including oral, sublingual, buccal, rectal, intravaginal, intrauterine, or topical administration. 
     For many applications these novel prostaglandin esters which I have obtained from certain specified phenols, naphthols, and hydroxyfluorenone have advantages over the corresponding known prostaglandin compounds. In oral administration these esters have shown surprisingly greater efficacy than the corresponding free acids or lower alkyl esters, whether because of longer duration of biological activity or because of improved lipophilicity and absorption is not certain. These esters offer a further advantage in that they have low solubility in water and the body fluids and are therefore retained longer at the site of administration. 
     A particularly outstanding advantage of many of these substituted phenyl and naphthyl and hydroxyfluorenone esters is that they are obtained in free-flowing crystalline form, generally of moderately high melting point, in the range 90°-180° C. This form is especially desirable for ease of handling, administering, and purifying. 
     These crystalline esters also provide a means of purifying PGF 2  α, 15-methyl-PGF 2  α, 15(R)-15-methyl-PGF 2  α, 15-ethyl-PGF 2  α, or 15(R)-15-ethyl-PGF 2  α, which are first converted to one of these esters, recrystallized until pure, and then recovered as the free acid. One method of recovering the free acid is by enzymatic hydrolysis of the ester, for example with a lipase. See German Pat. No. 2,242,792, Derwent Farmdoc No. 23047U. 
     To obtain the optimum combination of stability, duration of biological activity, lipohilicity, solubility, and crystallinity, certain compounds within the scope of formula III are preferred. 
     One preference is that Z is limited to either ##SPC7## 
     Another preference is that Z is further limited to ##SPC8## 
     wherein R is --CH 3  ##SPC9## 
     wherein R is --CH 3  ##SPC10## 
     --nh 2 . 
     another preference is that Z is limited to ##SPC11## 
     Another preference is that Z is limited to (1) ##SPC12## 
     wherein R is --CH 3  ##SPC13## 
     --nh 2  ##SPC14## 
     or (2) ##SPC15## 
     wherein R is ##SPC16## ##SPC17## 
     Especially preferred are those compounds which are in free-flowing crystalline form, including: 
     p-acetamidophenyl ester of PGF 2  α 
     p-benzamidophenyl ester of PGF 2  α 
     p-ureidophenyl ester of PGF 2  α 
     p-(3-phenylureido)phenyl ester of PGF 2  α 
     4-biphenylyl ester of PGF 2  α 
     p-tritylphenyl ester of PGF 2  α 
     p-(2-acetamido-2-carbamoylethyl)phenyl ester of PGF 2  α 
     p-(2-benzamido-2-carbamoylethyl)phenyl ester of PGF 2  α 
     α-semicarbazono-p-tolyl ester of PGF 2  α 
     p-acetylphenyl ester of PGF 2  α 
     p-benzoylphenyl ester of PGF 2  α 
     p-carbamoylphenyl ester of PGF 2  α 
     o-carbamoylphenyl ester of PGF 2  α 
     p-(methoxycarbonyl)phenyl ester of PGF 2  α 
     2-naphthyl ester of PGF 2  α 
     5-sulfamoyl-1-naphthyl ester of PGF 2  α 
     9-oxofluoren-4-yl ester of PGF 2  α 
     The substituted phenyl and naphthyl and 9-oxofluoren-4yl esters of PGF 2  α , 15-alkyl-PGF 2  α , and 15(R)-15-alkyl-PGF 2  α encompassed by formula III wherein Z is defined by ester groups A through Z are produced by the reactions and procedures described and exemplified hereinafter. For convenience, the above prostagladin or prostaglandin analog is referred to as the PG compound. The term phenol is used in a generic sense, for the hydroxy compounds, including phenols, naphthols, and hydroxyfluorenone. 
     Various methods are available for preparing these esters, differing as to yield and purity of product. Thus, by one method, the PG compound is converted to a tertiary amine salt, reacted with pivaloyl halide to give the mixed acid anhydride and then reacted with the phenol. Alternately, instead of pivaloyl halide, an alkyl or phenylsulfonyl halide is used, such as p-toluenesulfonyl chloride. See for example Belgian Pat. Nos. 775,106 and 776,294, Derwent Farmdoc Nos. 33705T and 39011T. 
     Still another method is by the use of the coupling reagent, dicyclohexylcarbodiimide. See Fieser et al., &#34;Reagents for Organic Synthesis&#34;, pp. 231-236, John Wiley and Sons, Inc., New York (1967). The PG compound is contacted with one to ten molar equivalents of the phenol in the presence of 2-10 molar equivalents of dicyclohexylcarbodiimide in pyridine as a solvent. 
     The preferred novel process for the preparation of these esters, however, comprises the steps (1) forming a mixed anhydride with the PG compound and isobutylchloroformate in the presence of a tertiary amine and (2) reacting the anyhydride with an appropriate phenol or naphthol. 
     The mixed anhydride is represented by the formula: ##SPC18## 
     for the optically active PG compounds, Y having the same definition as above. 
     The anhydride is formed readily at temperatures in the range -40° to +60° C., preferably at -10° to +10° C. so that the rate is reasonably fast and yet side reactions are minimized. The isobutylchloroformate reagent is preferably used in excess, for example 1.2 molar equivalents up to 4.0 per mole of the PG compound. The reaction is preferably done in a solvent and for this purpose acetone is preferred, although other relatively non-polar solvents are used such as acetonitrile, dichloromethane, and chloroform. The reaction is run in the presence of a tertiary amine, for example triethylamine, and the co-formed amine hydrochloride usually crystallizes out, but need not be removed for the next step. 
     The anhydride is usually not isolated but is reacted directly in solution with the phenol, preferably in the presence of a tertiary amine such as pyridine. 
     The phenol is preferably used in equivalent amounts or in excess to insure that all of the mixed anhydride is converted to ester. Excess phenol is separated from the product by methods described herein or known in the art, for example by crystallization. The tertiary amine is not only a basic catalyst for the esterification but also a convenient solvent. Other examples of tertiary amines useful for this purpose include N-methylmorpholine, triethylamine, diisopropylethylamine, and dimethylaniline. Although they may be used, 2-methylpyridine and quinoline result in a slow reaction. A highly hindered amine such as 2,6-dimethyllutidine is not useful because of the slowness of the reaction. 
     The reaction with the anhydride proceeds smoothly at room temperature (about 20° to 30° C.) and can be followed in the conventional manner with thin layer chromatography (TLC), usually being found complete within 1-4 hours. 
     The reaction mixture is worked up to yield the ester following methods known in the art, and the product is purified, for example by silica gel chromatography. 
     Solid esters are converted to a free-flowing crystalline form on crystallization from a variety of solvents, including ethyl acetate, tetrahydrofuran, methanol, and acetone, by cooling or evaporating a saturated solution of the ester in the solvent or by adding a miscible non-solvent such as diethyl ether, hexane, or water. The crystals are then collected by conventional techniques, e.g. filtration or centrifugation, washed with a small amount of solvent, and dried under reduced pressure. They may also be dried in a current of warm nitrogen or argon, or by warming to about 75° C. Although the crystals are normally pure enough for many applications, they may be recrystallized by the same general techniques to achieve improved purity after each recrystallization. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention can be more fully understood by the following examples. 
     All temperatures are in degrees centigrade. 
     Silica gel chromatography, as used herein, is understood to include chromatography on a column packed with silica gel, elution, collection of fractions, and combination of those fractions shown by thin layer chromatography (TLC) to contain the desired product free of starting material and impurities. 
     &#34;TLC&#34;, herein, refers to thin layer chromatography. 
     Preparation 1 p-Benzamidophenol 
     A solution of p-hydroxyaniline (20 g.) in 200 ml. of pyridine is treated with benzoic anhydride (20 g.). After 4 hr. at about 25° C., the mixture is concentrated under reduced pressure and the residue is taken up in 200 ml. of hot methanol and reprecipitated with 300 ml. of water. The product is recrystallized from hot acetonitrile as white crystals, 8.5 g., m.p. 218.0°-213.5° C. 
     Preparation 2 p-(p-Acetamidobenzamido)phenol 
     A solution of p-acetamidobenzoic acid (12.5 g.) in 250 ml. of tetrahydrofuran is treated with triethylamine (11.1 ml.). The mixture is then treated with isobutylchloroformate (10.4 ml.) and, after 5 min. at about 25° C., with p-aminophenol (13.3 g.) in 80 ml. of dry pyridine. After 40 min. the crude product is obtained by addition of 2 liters of water. The product is recrystallized from 500 ml. of hot methanol by dilution with 300 ml. of water as white crystals, 5.9 g., m.p. 275.0°-277.0° C. 
    
    
     EXAMPLE 1 
     p-Acetamidophenyl Ester of PGF 2  α (Formula III-A). 
     A solution of PGF 2  α (0.535 g.) and triethylamine (0.254 ml.) in 20 ml. of acetone is treated at -10° C. with isobutylchloroformate (0.238 ml.) whereupon triethylamine hydrochloride is precipitated. After 5 min. the mixture is treated with p-acetamidophenol (0.342 g.) in 5 ml. of pyridine for 3 hr. at about 25° C. The solvent is removed under reduced pressure and the residue taken up in acetonitrile and again concentrated. The crude residue is subjected to silica gel chromatography, eluting with ethyl acetate-methanol (90-10). The residue obtained by concentration of selected fractions, a solid on chilling, is the title compound 0.285 g., having R f  0.6 (TLC on silica gel in ethyl acetate-methanol 90:10). It is recrystallized from ethyl acetate-hexane as white free-flowing crystals, m.p. 114°-115.8° C. 
     EXAMPLE 2 
     p-Benzamidophenyl Ester of PGF 2  α (Formula III-B) 
     Following the procedure of Example 1 but using 0.535 g. of PGF 2  α, 0.254 ml. of triethylamine, 0.238 ml. of isobutylchloroformate, and 0.481 g. of p-benzamidophenol (Preparation 1), there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate followed by ethyl acetate-methanol (95:5). The residue obtained by concentration of selected fractions, 0.220 g., is crystallized from ethyl acetate-methanol (100:5) diluted with hexane as the title compound, white free-flowing crystals, m.p. 139.8°-143.8° C., having R f  0.8 (TLC on silica gel in ethyl acetate-methanol (95:5)). 
     EXAMPLE 3 
     p-Ureidophenyl Ester of PGF 2  α  (Formula III-E) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.306 ml. of triethylamine, 0.288 ml. of isobutylchloroformate, and 0.330 g. of p-hydroxyphenylurea, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-acetone (4:1). The residue obtained by concentration of selected fractions, 0.488 g., is crystallized from acetone diluted with one-half the volume of hexane as the title compound, white free-flowing crystals, m.p. 133.8°-135.0° C. having R f  0.5 (TLC on silica gel in ethyl acetate-acetone (4:1). 
     EXAMPLE 4 
     p-(3-Phenylureido)phenyl Ester of PGF 2  α  (Formula III-F) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.347 ml. of triethylamine, 0.326 ml. of isobutylchloroformate, and 0.705 g. of p-hydroxy-1,3-diphenylurea, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-acetone (7:3). The residue obtained by concentration of selected fractions, 0.475 g., is crystallized from hot ethyl acetate as the title compound, white free-flowing crystals, m.p. 145.0°-147.3° C., having R f  0.42 (TLC on silica gel in ethyl acetate-acetone (7:3). 
     EXAMPLE 5 
     p-Biphenyl Ester of PGF 2  α  (Formula III-G) 
     Following the procedure of Example 1 but using 0.535 g. of PGF 2  α, 0.254 ml. of triethylamine, 0.238 ml. of isobutylchloroformate, and 0.385 g. of p-phenylphenol, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate followed by acetonitrile. The residue obtained by concentration of selected fractions, 0.270 g., is crystallized from ethyl acetate diluted with an equal volume of hexane as the title compound, white free-flowing crystals, m.p. 114.3°-116.8° C. having R f  0.25 (TLC on silica gel in ethyl acetate). 
     EXAMPLE 6 
     p-Tritylphenyl Ester of PGF 2  α  (Formula III-H) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.291 ml. of triethylamine, 0.275 ml. of isobutylchloroformate, and 0.840 g. of p-tritylphenol, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-water (99:1). The residue obtained by concentration of selected fractions, 0.576 g., is crystallized from acetone diluted with five volumes of hexane as the title compound, white free-flowing crystals, m.p. 123.8°-129.0°, having R f  0.5 (TLC on silica gel in ethyl acetate). 
     EXAMPLE 7 
     p-(2-Acetamido-2-carbamoylethyl)phenyl Ester of PGF 2  α  (Formula III-I) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.306 ml. of triethylamine, 0.288 ml. of isobutylchloroformate, and 0.488 g. of N-acetyl-L-tyrosinamide, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting successively with ethyl acetate-methanol-water (90:10:1) and ethyl acetate-methanol-water (80:20:1). The major fraction is chromatographed again, eluting eith ethyl acetate-methanol (4:1). The residue obtained by concentration of selected fractions, 0.242 g. is crystallized from acetone diluted with 1.5 volumes of hexane as the title compound, white free-flowing crystals, m.p. 109.8°-113.8° with softening at 105.0° having R f  0.5 (TLC on silica gel in ethyl acetate-methanol (4:1)). 
     EXAMPLE 8 
     p-(2-Benzamido-2-carbamoylethyl)phenyl Ester of PGF 2  α  (Formula III-J) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.306 ml. of triethylamine, 0.288 ml. of isobutylchloroformate, and 0.625 g. of N-benzoyl-L-tyrosinamide, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-tetrahydrofuran-water (60:40:1). The residue obtained by concentration of selected fractions, 0.459 g., is crystallized from hot acetonitrile as the title compound, white free-flowing crystals, m.p. 142.5°-144.3° C., having R f  0.5 (TLC on silica gel in ethyl acetate-tetrahydrofuran (3:2)). 
     EXAMPLE 9 
     α-Semicarbazono-p-tolyl Ester of PGF 2  α  (Formula III-K) 
     Following the procedure of Example 1 but using 0.535 g. of PGF 2  α , 0.254 ml. of triethylamine, 0.238 ml. of isobutylchloroformate, and 0.405 g. of p-hydroxybenzaldehyde semicarbazone, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-methanol (9:1) and ethyl acetate-methanol (8:2). The residue obtained by concentration of selected fractions, 0.215 g., is crystallized from ethyl acetate-hexane (1:1) as the title compound, white free-flowing crystals, m.p. 110.8°-113.3° C. having R f  0.4 (TLC on silica gel in ethyl acetate-methanol (9:1)). 
     EXAMPLE 10 
     p-Acetylphenyl Ester of PGF 2  α  (Formula III-L) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.306 ml. of triethylamine, 0.288 ml. of isobutylchloroformate, and 0.299 g. of p-hydroxyacetophenone, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-water (99:1) followed by ethyl acetate-acetonitrile (1:1). The residue obtained by concentration of selected fractions, 0.589 g. is crystallized from ethyl acetate diluted with an equal volume of hexane as the title compound, white free-flowing crystals, m.p. 85.3°-86.5° C. having R f  0.4 (TLC on silica gel in ethyl acetate-acetonitrile (4:1)). 
     EXAMPLE 11 
     p-Benzoylphenyl Ester of PGF 2  α  (Formula III-M) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.291 ml. of triethylamine, 0.275 ml. of isobutylchloroformate, and 0.594 g. of p-hydroxybenzophenone, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-water (99:1). The residue obtained by concentration of selected fractions, 0.492 g., is crystallized from ethyl acetate diluted with three volumes of hexane as the title compound, white free-flowing crystals, m.p. 73.8°-75.8° C., having R f  0.5 (TLC on silica gel in ethyl acetate). 
     EXAMPLE 12 
     p-Carbamoylphenyl Ester of PGF 2  α  (Formula III-N) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.347 ml. of triethylamine, 0.326 ml. of isobutylchloroformate, and 0.433 g. of p-hydroxybenzamide, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-acetone (3:7). The residue obtained by concentration of selected fractions, 0.455 g., is crystallized from acetone diluted with an equal volume of acetonitrile as the title compound, white, free-flowing crystals, m.p. 129.5°-130.8° C., having R f  0.32 (TLC on silica gel in ethyl acetate-acetone (3:7). 
     EXAMPLE 13 
     o-Carbamoylphenyl Ester of PGF 2  α  (Formula III-O) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.306 ml. of triethylamine, 0.288 ml. of isobutylchloroformate, and 0.299 g. of o-hydroxybenzamide, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-acetone-water (25:75:1). The residue obtained by concentration of selected fractions, 0.296 g., is crystallized from ethyl acetate diluted with 1.5 volumes of hexane as the title compound, white free-flowing crystals, m.p., 98.5°-100.1° C. having R f  0.55 (TLC on silica gel in ethyl acetate-acetone (1:3)). 
     EXAMPLE 14 
     p-(Methoxycarbonyl)phenyl Ester of PGF 2  α  (Formula III-Q) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.347 ml. of triethylamine, 0.326 ml. of isobutylchloroformate, and 0.474 g. of methyl p-hydroxybenzoate, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-water (99:1) followed by ethyl acetate-acetone-water (69:30:1). The residue obtained by concentration of selected fractions, 0.678 g., is crystallized from ethyl acetate diluted with an equal volume of hexane as the title compound, white free-flowing crystals, m.p. 80.3°-82.0° C., having R f  0.3 (TLC on silica gel in ethyl acetate). 
     EXAMPLE 15 
     2-Naphthyl Ester of PGF 2  α  (Formula III-X) 
     Following the procedure of Example 1 but using 0.535 g. of PGF 2  α , 0.254 ml. of triethylamine, 0.238 ml. of isobutylchloroformate, and 0.327 g. of β-naphthol, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate followed by acetonitrile. The residue obtained by concentration of selected fractions, 0.410 g., is crystallized from ethyl acetate diluted with 1.5 volumes of hexane as the title compound, white free-flowing crystals, m.p. 98.8°-100° C. having R f  0.25 (TLC on silica gel in ethyl acetate). 
     EXAMPLE 16 
     5-Sulfamoyl-1-naphthyl Ester of PGF 2  α  (Formula III-Y) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.347 ml. of triethylamine, 0.326 ml. of isobutylchloroformate, and 0.696 g. of 1-hydroxy-5-naphthalenesulfonamide there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting successively with ethyl acetate and ethyl acetate-acetone (1:1). The major fraction is chromatographed again, eluting with ethyl acetate-acetone (9:1). The residue obtained by concentration of selected fractions, 0.450 g., an oil, is the title compound, having R f  0.4 (TLC on silica gel in ethyl acetate). 
     EXAMPLE 17 
     9-Oxofluoren-4-yl Ester of PGF 2  α  (Formula III-Z) 
     Following the procedure of Example 1 but using 0.738 g. of PGF 2  α , 0.347 ml. of triethylamine, 0.326 ml. of isobutylchloroformate, and 0.612 g. of 4-hydroxy-9-fluorenone, there is obtained a crude residue. This residue is subjected to silica gel chromatography, eluting with ethyl acetate-water (99:1) followed by ethyl acetate-acetone-water (70:30:1). The residue obtained by concentration of selected fractions, 0.650 g., is crystallized from ethyl acetate-hexane (10:7) as the title compound, white free-flowing crystals, m.p. 83.8°-86.8° C. having R f  0.27 (TLC on silica gel in ethyl acetate). 
     Following the procedures of Examples 1- 17 but employing the racemic forms of the PG compounds, there are obtained the corresponding esters of racemic PG compounds. 
     EXAMPLES 18-78 
     The substituted phenyl and naphthyl and hydroxylfluorenone esters of PGF 2  α , 15-methyl-PGF 2  α , and 15(R)-15-methyl-PGF 2  α  of Tables I-III below are obtained following the procedures of Example 1, wherein the prostaglandin compound is reacted in the presence of triethylamine and isobutylchloroformate with the appropriate hydroxy phenyl or naphthyl compound, listed in the Table. These phenols or naphthols are readily available or prepared by methods described herein or known in the art. The crude products, obtained in concentration under reduced pressure, are purified by means described herein or known in the art, including partitioning, solvent extraction, washing, silica gel chromatography, trituration, or crystallization. 
     Following the procedures of Examples 18-78 but employing the racemic forms of the PG compounds, there are obtained the corresponding esters of the racemic PG compounds. 
     
                       TABLE I______________________________________Esters of PGF.sub.2 α Hydroxy Phenyl or   Product PGF.sub.2 αEx.   Naphthyl Compound   Ester of formula:______________________________________18    p-(p-acetamidobenzamido)-                     III-C phenol19    p-(p-benzoamidobenzamido)-                     III-D phenol20    N-(p-tritylphenyl)-p-                     III-P hydroxybenzamide21    hydroquinone benzoate                     III-R22    hydroquinone, p-acetamido-                     III-S benzoic acid ester23    2,4-diacetamidophenol                     III-T24    1-acetamido-4-hydroxy-                     III-U naphthalene25    1-benzamido-4-hydroxy-                     III-V naphthalene26    1-hydroxy-4-ureido- III-W naphthalene______________________________________ 
    
     
                       TABLE II______________________________________Esters of 15-Methyl-PGF.sub.2 αHydroxy Phenyl or  Product 15-Methyl-Ex.  Naphthyl Compound  PGF.sub.2 α Ester of formula:______________________________________27   p-acetamidophenol       III-A28   p-benzamidophenol       III-B29   p-(p-acetamidobenzamido)-                        III-Cphenol30   p-(p-benzamidobenzamido)-                        III-Dphenol31   p-hydroxyphenylurea     III-E32   p-hydroxy-1,3-diphenylurea                        III-F33   p-phenylphenol          III-G34   p-tritylphenol          III-H35   N-acetyl-L-tyrosinamide III-I36   N-benzoyl-L-tyrosinamide                        III-J37   p-hydroxybenzaldehyde   III-Ksemicarbazone38   p-hydroxyacetophenone   III-L39   p-hydroxybenzophenone   III-M40   p-hydroxybenzamide      III-N41   o-hydroxybenzamide      III-O42   N-(p-tritylphenyl)-p-   III-Phydroxybenzamide43   p-hydroxybenzoic acid,  III-Qmethyl ester44   hydroquinone benzoate   III-R45   hydroquinone, p-acetamido-                        III-Sbenzoic acid ester46   2,4-diacetamidophenol   III-T47   1-acetamido-4-hydroxy-  III-Unaphthalene48   1-benzamido-4-hydroxy-  III-Vnaphthalene49   1-hydroxy-4-ureido-     III-Wnaphthalene50   2-naphthol              III-X51   1-hydroxy-5-naphthalene-                        III-Ysulfonamide52   4-hydroxy-9-fluorenone  III-Z______________________________________ 
    
     
                       TABLE III______________________________________Esters of 15(R)-15-Methyl-PGF.sub.2 α                       Product 15(R)-Hydroxy Phenyl or      15-Methyl PGF.sub.2 αEx.  Naphthyl Compound      Ester of formula:______________________________________53   p-acetamidophenol      III-A54   p-benzamidophenol      III-B55   p-(p-acetamidobenzamido)-                       III-Cphenol56   p-(p-benzamidobenzamido)-                       III-Dphenol57   p-hydroxyphenylurea    III-E58   p-hydroxy-1,3-diphenylurea                       III-F59   p-phenylphenol         III-G60   p-tritylphenol         III-H61   N-acetyl-L-tyrosinamide                       III-I62   N-benzoyl-L-tyrosinamide                       III-J63   p-hydroxybenzaldehyde semicarbazone                       III-K64   p-hydroxyacetophenone  III-L65   p-hydroxybenzophenone  III-M66   p-hydroxybenzamide     III-N67   o-hydroxybenzamide     III-O68   N-(p-tritylphenyl)-p-hydroxybenzamide                       III-P69   p-hydroxybenzoic acid, methyl ester                       III-Q70   hydroquinone benzoate  III-R71   hydroquinone, p-acetamido-                       III-Sbenzoic acid ester72   2,4-diacetamidophenol  III-T73   1-acetamido-4-hydroxy-naphthalene                       III-U74   1-benzamido-4-hydroxy-naphthalene                       III-V75   1-hydroxy-4-ureido-naphthalene                       III-W76   2-naphthol             III-X77   1-hydroxy-5-naphthalene-                       III-Ysulfonamide78   4-hydroxy-9-fluorenone III-Z______________________________________