4,5.alpha.-Epoxy-3-hydroxy or methoxy-7-(1-hydroxy-alkyl or 1-oxoalkyl)morphinan-6-one compounds

Abstract

Disclosed are 4,5.alpha.-epoxy-3-hydroxy or methoxy-7-(1-hydroxyalkyl or 1-oxoalkyl)morphinan-6-one compounds characterized by the structural formulae: ##STR1## In the foregoing formulae R is methyl, cyclopropylmethyl, cyclobutylmethyl, propargyl, allyl, dimethylallyl, cis-chloroallyl or furfuryl; R.sub.1 is H or methyl; R.sub.2 is straight or branched chain alkyl of from 1 to 10 carbon atoms, aryl, substituted aryl or arylalkyl, in which the alkyl group contains from 1 to 6 carbon atoms, and R.sub.3 is a straight chain alkyl of 1 to 4 carbon atoms.

Description

BACKGROUND OF THE INVENTION

Certain well known narcotic analgesics belong to the class of 4,5.alpha.-epoxymorphinan compounds which have the following basic ring system, in which the atoms are numbered as indicated. ##STR2##

The two most familiar compounds of this class are morphine and its 3-methyl ether, codeine, with the structures indicated below. ##STR3##

When the 6-hydroxyl group of each of these compounds is oxidized to an oxo group, the compounds conveniently are referred to as morphinone and codeinone, respectively. When the N-methyl groups of the latter compounds are replaced by other substituent groups they may be referred to as N-substituted normorphinones and norcodeinones, respectively. There are two types of nomenclature commonly used for describing compounds herein. The trivial names, such as morphine or morphinone, are widely accepted and used for the sake of brevity and clarity. The Chemical Abstracts nomenclature is preferred and is used whereever precision is needed.

Morphine and its relatives are used primarily for the relief of pain (i.e., as analgesics). They are narcotic and possess dependence-inducing ability and produce other side effects that make them less than ideal analgesics (emesis, constipation, sweating, respiratory depressions, miosis). A compound with the appropriate profile of analgesic (agonist) and narcotic antagonist actions which is not morphine-like has potential as an analgesic agent for treatment of moderate to severe pain without liability of drug dependence. Furthermore, a compound having only strong narcotic antagonist action may be a desirable agent for treatment of drug dependence.

Bentley and Hardy disclose in Journal of the American Chemical Society, 89:13, Pp. 3267-73 certain Diels-Alder adducts of thebaine having the formula: ##STR4## where R is methyl or phenyl. It is stated that these compounds possess analgesic activity. The 6,14-endoethenotetrahydrothebaine (oripavine) series of analgesics as disclosed by Bentley and his coworkers differs from the present series by the presence of the 6,14-ethenobridge in the oripavines. This bridge alters the stereochemistry of the molecules. Furthermore, the oripavines contain a methyl ether of a tertiary alcohol at C-6 whereas the present series contains a keto group at that position. No specific data on the analgesic activity of the 7-acyl oripavines are given. The analgesic activity of the side chain tertiary alcohols in the oripavine series generally increases through R.dbd.C.sub.3 H.sub.7 and then decreases. The morphine antagonist activity for the N--CH.sub.2 --cC.sub.3 H.sub.5 derivatives decreases with the increase in the size of R.

SUMMARY OF THE INVENTION

The present invention involves 4,5.alpha.-epoxy-3-hydroxy or methoxy-7-(1-hydroxyalkyl or 1-oxoalkyl)morphinan-6-one compounds characterized by the structural formulae: ##STR5## In the foregoing formulae R is methyl, cyclopropylmethyl, cyclobutylmethyl, propargyl, allyl, dimethylallyl, cis-chloroallyl, or furfuryl; R.sub.1 is H or methyl; R.sub.2 is straight or branched chain alkyl of from 1 to 10 carbon atoms, aryl, substituted aryl or arylalkyl in which the alkyl chain contains from 1 to 6 carbon atoms and R.sub.3 is a straight chain alkyl group of 1 to 4 carbon atoms.

DETAILED DESCRIPTION

The preparation of the compounds of the present invention is outlined in Scheme I. ##STR6##

Referring to Scheme I, Compound (2) is prepared by reacting Compound (1) [I. Seki, Yagugaku Zasshi 84, 615 (1964) CA: 61:9544 (1964)] where R is methyl, cyclopropylmethyl, cyclobutylmethyl, propargyl, allyl, dimethylallyl, cis-chloroallyl, furfuryl with an acyl chloride in the presence of triethylamine followed by treatment with water.

Suitable acyl halides include compounds of the formula: ##STR7## in which R.sub.2 is a straight or branched chain alkyl of 1 to 10 carbon atoms, e.g., methyl, ethyl, propyl, isopropyl, pentyl, heptyl or decyl; aryl, e.g., phenyl, naphthyl and heteroaryls including furanyl; or substituted aryl, e.g., p-fluorophenyl, trimethylphenyl, nitrophenyl and methoxyphenyl; and arylalkyl, e.g., phenethyl. The reaction is carried out in a suitable inert solvent, such as benzene, toluene and the halogenated hydrocarbons chloroform and trichloroethylene with or without the addition of an organic base at a temperature in the range of from 25.degree. C. to 150.degree. C. for a period sufficient to form the desired intermediate which is converted to Compound (2) by adding water to the reaction medium. Recovery and purification of Compound (2) is accomplished by treatment with base, followed by extraction and chromatographic purification. Compound (2) is converted to Compound (3) (its 3-hydroxy counterpart) by reaction with boron tribromide in a suitable inert solvent at room temperature. The compounds of Formula 2 and 3 are important in that they can be converted to the tertiary alcohol 4 by the addition of an alkyl lithium reagent of the formula R.sub.3 Li where R.sub.3 is a straight chain alkyl group of 1 to 4 carbon atoms. This reaction is carried out in a suitable solvent such as tetrahydrofuran, diethyl ether or dimethoxyethane at a temperature of from -90.degree. to +25.degree. C. We have found temperatures on the order of -78.degree. C. to be preferable.

Certain of the compounds corresponding to Formulae 2, 3 and 4 have been found to have analgesic activity, narcotic antagonist activity or a combination of these activities which render them useful as nonaddictive strong analgesics.

The preparation of the morphinan compounds of the present invention is further illustrated by the following examples.

EXAMPLE I

Preparation of 7-(4-Phenylbutyroyl)Dihydrocodeinone ##STR8## To a cooled solution of 6 g. of the morpholine enamine of dihydrocodeinone (1) in 5.6 g. of dry triethylamine and 350 ml. of trichloroethylene was slowly added 10.04 g. of 4-phenylbutyroyl chloride in 50 ml. of trichloroethylene. After 1.5 hr. the ice bath was replaced with a heating bath and the solution was refluxed for 8.5 hr. then allowed to stir at room temperature overnight.

After addition of 100 ml. of water the mixture was refluxed for 2 hr. After cooling, the mixture was basified with concentrated ammonium hydroxide whereupon the aqueous phase was separated and extracted twice with chloroform. The combined organic layers were dried (Na.sub.2 SO.sub.4) and concentrated in vacuo. The residue was dissolved in methanol, and stirred with about 10 g. of solid potassium carbonate for 5.5 hr. The solution was filtered and concentrated in vacuo and the residue partitioned between diethyl ether and water. The aqueous layer was extracted three times with diethyl ether at which point the combined ether layers were dried (Na.sub.2 SO.sub.4) and concentrated to afford 14.2 g. of an oil. Chromatography of this oil on 300 g. of silica gel afforded 3.40 g. (49% yield) of 7-(4-phenylbutyroyl)dihydrocodeinone (2) upon elution with graded methanol-chloroform mixtures. Recrystallization from ethanol afforded a solid melting at 170.degree.-171.5.degree. C.

Anal. Calc. for C.sub.20 H.sub.3 NO.sub.4 : C, 75.48; H, 7.01; N, 3.14. Found: C, 75.46; H, 7.08; N, 3.12.

Mass Spec. (m/e) 445 (M+).

EXAMPLE II

Preparation of 7-(4-Phenylbutyroyl)Dihydromorphone ##STR9## To a solution of 8.9 ml. of boron tribromide in 150 ml. of chloroform was added, dropwise, a solution of 3.4 g. 7-(4-phenylbutyroyl)dihydrocodeinone (2) in 100 ml. of chloroform. After stirring for one additional hour, the reaction mixture was quenched by pouring it into a stirred mixture of ice and concentrated ammonium hydroxide (1:1). After stirring for 1 hr. the aqueous layer was separated and extracted twice with chloroform. The combined chloroform layers were dried (Na.sub.2 SO.sub.4) and concentrated in vacuo to afford 3.5 g. of a gummy solid. This material was chromatographed on 90 g. of silica gel. Elution with graded methanol-chloroform mixtures afforded 2.19 g. (65% yield) of 7-(4-phenylbutyroyl)dihydrobromorphone (3).

The material forms a hydrochloride salt which decomposes at 175.degree. C.

Mass spec. (m/e) 431 (M.sup.+ ; free base).

EXAMPLE III

Preparation of 17-Cyclopropylmethyl-4,5.alpha.-Epoxy-3-Hydroxy-7-(1-Hydroxy-1-Methylbutyl)Morphinan-6-One ##STR10## To 375 mg. of 17-cyclopropylmethyl-4,5.alpha.-epoxy-3-hydroxy-7-butanoylmorphinan-6-one (4) in 10 ml. of dry tetrahydrofuran at -78.degree. C. was added, dropwise, 6 ml. of 1.6 M methyl lithium. The mixture was then allowed to warm slowly (over 2 hr.) to -55.degree. C. The mixture was then quenched by the sequential addition of moist diethyl ether and saturated aqueous ammonium chloride. After acidification with acetic acid and rebasification with ammonium hydroxide the aqueous solution was extracted with chloroform. The organic layer was dried (Na.sub.2 SO.sub.4) and concentrated to afford 362 mg. of crude oil. Chromatography on 8 g. of silica gel with graded methanol-chloroform mixtures afforded a fraction rich in (5) which was purified further by preparative tlc to afford 121 mg. (29%) of 17-cyclopropylmethyl-4,5.alpha.-epoxy-3-hydroxy-7-(1-hydroxy-1-methylbutyl)morphinan-6-one as a glassy foam.

Mass spec. (m/e) 411 (M.sup.+); 393 (M.sup.+ -18).

Other compounds within the scope of the present invention are prepared by the procedure of the examples using the appropriate starting materials. The physical characteristics of these compounds, whose structures can be determined by reference to Tables I and II, supra, are set out in the following table.

__________________________________________________________________________PHYSICAL DATA ON COMPOUNDS OF THIS INVENTIONFree Base Mass AnalysisCom- mp spec M+ FORMULA Calculated Found HCl saltpound (.degree.C.) MW (m/e) (free base or HCl salt) C H N C H N mp(.degree.C.)__________________________________________________________________________TR5463 164-5 381 C.sub.23 H.sub.27 NO.sub.4 72.42 7.13 3.61 72.34 7.14 3.67TR5475 135 367 367 C.sub.22 H.sub.25 NO.sub.4.0.5CH.sub.3 OH 70.46 7.11 3.65 70.92 6.92 3.72TR5570 395 395 C.sub.24 H.sub.29 NO.sub.4.HCl.2H.sub.2 O 61.50 7.33 2.97 60.86 6.53 2.96 170(dec)TR5573 381 C.sub.23 H.sub.27 NO.sub.4.HCl.2H.sub.2 O 60.84 7.12 3.08 59.71 6.42 3.05 215(dec)TR5464 409 C.sub.25 H.sub.31 NO.sub.4.HCl.H.sub.2 O 64.71 7.39 3.02 64.81 7.00 3.04 155TR5476 393 C.sub.24 H.sub.29 NO.sub.4.HCl.H.sub.2 O 64.05 7.18 3.11 64.01 7.20 3.09TR5519 423 C.sub.26 H.sub.33 NO.sub.4.HCl.0.5H.sub.2 O 66.56 7.52 2.99 66.41 7.55 2.99TR5520 409 C.sub.25 H.sub.31 NO.sub.4.HCl 67.33 7.23 3.14 67.13 7.30 3.13 >240TR5504 437 C.sub.27 H.sub.35 NO.sub.4.HCl.H.sub.2 O 65.89 7.80 2.85 66.04 7.43 2.86 135TR5505 423 C.sub.26 H.sub.33 NO.sub.4.HCl.H.sub.2 O 65.32 7.61 2.93 65.26 7.59 2.91 190(dec)TR5539 451 C.sub.28 H.sub.37 NO.sub.4.HCl.0.5H.sub.2 O 67.64 7.92 2.82 68.09 7.79 2.81TR5540 437 437 C.sub.27 H.sub.35 NO.sub.4.HCl.0.5H.sub.2 O 67.13 7.72 2.90 67.08 7.75 2.90 175TR5509 409 409 C.sub.25 H.sub.31 NO.sub.4.HCl.H.sub.2 O 64.70 7.40 3.02 67.86 6.89 2.92 190(dec)TR5511 395 395 C.sub.24 H.sub.29 NO.sub.4.HCl.H.sub.2 O 64.05 7.18 3.11 62.64 6.78 2.95TR5571 437 C.sub.27 H.sub.35 NO.sub.4.HCl.H.sub.2 O 65.90 7.78 2.84 65.84 7.25 2.94 170(dec)TR5574 423 C.sub.26 H.sub.33 NO.sub.4.HCl.H.sub.2 O 65.32 7.59 2.93 65.29 7.60 2.93 213-5TR5577 457 457 C.sub.29 H.sub.31 NO.sub.4.HCl 70.50 6.53 2.84 69.22 6.18 2.40 167-70 (contains some pyrone)TR5506 429 429 C.sub.27 H.sub.27 NO.sub.4.HClTR5501 443 443 C.sub.28 H.sub.29 NO.sub.4.HCl.H.sub.2 O 66.45 6.19 2.77 67.53 6.30 3.72 140TR5579 155-7 447 C.sub.27 H.sub.26 FNO.sub.4 72.47 5.96 3.13 72.37 5.88 3.10TR5575 461 461 C.sub.28 H.sub.28 FNO.sub.4.HCl.H.sub.2 O 65.16 6.07 2.71 64.53 5.76 2.67 178-80TR (dec)5649 145 428 C.sub.25 H.sub.25 NO.sub.5.0.5H.sub.2 O 70.07 6.12 3.27 70.11 6.18 3.27TR5634 433 C.sub.26 H.sub.27 NO.sub.5.HCl.1.5H.sub.2 O 62.83 6.29 2.82 62.86 6.32 2.82 186-8MLS5695H 355 355 C.sub.21 H.sub.25 NO.sub.4.HCl.H.sub.2 O 61.53 6.89 3.41 61.30 6.88 3.41MLS5689H 383 383 C.sub.23 H.sub.29 NO.sub.4 .HCl--0.6CHCl.sub.3 57.65 6.28 2.85 57.61 6.50 3.05 160(dec)MLS5690H 417 417 C.sub.26 H.sub.27 NO.sub.4.HCl--0.5CHCl.sub.3 61.96 5.60 2.73 61.39 5.77 2.85 175(dec)MLS5691H 431 431 C.sub.27 H.sub.24 NO.sub.4.HCl.0.7CHCl.sub.3 60.31 5.62 2.54 60.41 5.93 2.66 175(dec)MLS5692 160-1.5 369 369 C.sub.22 H.sub.27 NO.sub.4.0.25H.sub.2 O 70.56 7.53 3.74 70.60 7.64 3.88MLS5682 155-6 397 C.sub.24 H.sub.31 NO.sub.4 72.51 7.86 3.52 72.44 7.86 3.52MLS5683 170-1.5 445 C.sub.28 H.sub.31 NO.sub.4 75.48 7.01 3.14 75.46 7.08 3.12MLS5688H 431 431 C.sub.27 H.sub.29 NO.sub.4.HCl.H.sub.2 O 66.71 6.65 2.88 67.30 6.71 2.91 (125(dec)TR5492 oil 357 357 C.sub.21 H.sub.27 NO.sub.4TR5479 oil 397 397 C.sub.24 H.sub.31 NO.sub.4TR5499 foam 425 425 C.sub.26 H.sub.35 NO.sub.4.0.2CHCl.sub.3 70.20 7.90 3.12 70.14 7.81 3.28TR5544 foam 439 439 C.sub.27 H.sub.37 NO.sub.4 73.76 8.50 3.19 72.83 8.35 3.06TR5543 foam 411 411 C.sub.25 H.sub.33 NO.sub.4.0.3CHCl.sub.3 67.90 7.51 3.13 67.84 7.54 3.17TR5551 134-7 425 425 C.sub.26 H.sub.35 NO.sub.4 73.38 8.29 3.29 71.47 7.37 3.79 (reverse aldol on heating)TR5538 foam 439 439 C.sub.27 H.sub.27 NO.sub.4.0.1CHCl.sub.3 72.07 8.30 3.10 72.43 8.29 3.27TR5572 195-7 411 411 C.sub.25 H.sub.33 NO.sub.4.0.4CHCl.sub.3 66.40 7.34 3.05 65.77 7.52 2.45MLS5694 194-5 399 399 C.sub.24 H.sub.33 NO.sub.4 72.15 8.33 3.51 72.04 8.33 3.47__________________________________________________________________________

PHARMACOLOGICAL EVALUATION

The compounds whose preparation is disclosed in the foregoing examples were screened to determine the following biological activities:

(A) Analgesic effects upon mice (acetic acid writhing test). (B) Narcotic antagonist activity in rats (modified rat tail flick test).

TEST A. ACETIC ACID MOUSE WRITHING TEST

The analgesic effects of test compounds were determined in mice by use of the acetic acid writhing test described by B. A. Whittle, Brit. J. Pharmacol., 22:246 (1964). In this test at least three groups of five male CD-1 mice each were given subcutaneous doses of the test drug dissolved in either distilled water or distilled water acidified with HCl depending on the solubility of the compound. Fifteen (15) minutes post drug, 0.4 milliliter of a 0.75% or 1.0% or 0.6 milliliter of a 1.0% V/V acetic acid in distilled water solution was administered intraperitoneally. The number of writhes in a 20 minute interval beginning 5 minutes after the acetic acid injection were determined and compared with the number of writhes in control groups which had received only acetic acid.

Percent inhibition of writhing was calculated as: ##EQU1##

The ED.sub.50 dose, i.e., the dose required to reduce the number of writhes by 50%, was determined graphically from a plot of % inhibition as a probit versus log dose. Confidence limits of 95% were calculated on the basis of those results falling in the range 16-84% inhibition. See Litchfield, J. T. and Wilcoxon, F., J. Pharmacol. Exp. Ther., 96:99, (1949).

TEST B. EVALUATION OF NARCOTIC ANTAGONIST

The narcotic antagonist effects of test compounds were determined by a modification of the rat tail flick procedure of Harris and Pierson, J. Pharmacol. Exp. Ther. 143:141 (1964).

Male albino Wistar rats (100-120 g.) were used for this study. A rat's tail is so placed so as to cover a photocell. Heat is applied by a lamp in a reflector with a timer being connected to the lamp and photocell so that the timer goes on when the light is turned on and is turned off when the photocell is uncovered. A rheostat, incorporated into a heating lamp is used to adjust the intensity of the light falling on the tail of the rat such that the rat's control reaction time is from 1.2 to 5.8 seconds. Animals with a control reaction time outside this range are rejected. The rheostat adjustment is made only if a significant proportion (more than 1 out of every 10 rats) of the reaction times are outside the range of 1.2 to 5.8 seconds. Groups of five rats were used each time, and two control times were determined at least 30 minutes apart.

The test drug was given intraperitoneally and this was followed ten minutes later by an ED.sub.80 dose of morphine subcutaneously. The animals were retested at 20 minutes after the morphine injection. Control animals were given morphine only. A ten second cutoff time is employed; if the rat does not flick its tail in 10 seconds it is is removed from the heat source. The data were calculated as follows: ##EQU2##

The data were plotted on log-probit paper and AD.sub.50 values, i.e., the dose required to inhibit the morphine effect by 50% within 95% confidence limits, were determined by the method of Litchfield and Wilcoxon.

The 4,5.alpha.-epoxy-3-hydroxy or methoxy-7-(1-hydroxyalkyl)morphinan-6-one data is tabulated in Table I whereas Table II sets out the data for the 1-hydroxyalkyl compounds. In the following tables CPM means "cyclopropylmethyl", NDR means "no dose response" and the designation X% (Y) means that the number of writhes were reduced by X% at a dosage of Y mg/kg.

TABLE I______________________________________ ##STR11## ED.sub.50 AD.sub.50Compound RR.sub.1 R.sub.2 (mg/kg) (mg/kg)______________________________________TR-5463 CPMCH.sub.3 CH.sub.3 9%(10) Ia(10)TR-5475 CPMH CH.sub.3 4.05 1.3TR-5570 CPMCH.sub.3 C.sub.2 H.sub.5 11%(10) 6.5TR-5573 CPMH C.sub.2 H.sub.5 Ia(10) 0.51TR-5464 CPMCH.sub.3 C.sub.3 H.sub.7 2.81 8.1TR-5476 CPMH C.sub.3 H.sub.7 4.65 2.55TR-5519 CPMCH.sub.3 C.sub.4 H.sub.9 >10.0 Ia(10)TR-5520 CPMH C.sub.4 H.sub.9 1.59 77%(10)TR-5504 CPMCH.sub.3 C.sub.5 H.sub.11 5.7 Ia(10)TR-5505 CPMH C.sub.5 H.sub.11 0.29 22TR-5539 CPMCH.sub.3 C.sub.6 H.sub.13 >10.0 >10.0TR-5540 CPMH C.sub.6 H.sub.13 0.4 Ia(10)TR-5509 CPMCH.sub.3 i-C.sub.3 H.sub.7 7.5 2.8TR-5511 CPMH i-C.sub. 3 H.sub.7 >10 0.81TR-5571 CPMCH.sub.3 t-C.sub.4 H.sub.9 Ia(10) 13%(10)TR-5574 CPMH CH.sub.2 t-C.sub.4 H.sub.9 Ia(10) >10TR-5577 CPMCH.sub.3 CH.sub.2 C.sub.6 H.sub.5 21%(10) Ia(10)TR-5506 CPMH C.sub.6 H.sub.5 4.35 0.24TR-5501 CPMCH.sub.3 C.sub.6 H.sub.5 11.3 8.0TR-5579 CPMH C.sub.6 H.sub.4pF 29%(10) 45%(10)TR-5575 CPMCH.sub.3 C.sub.6 H.sub.4pF Ia(10) 17%(10)TR-5649 CPMH C.sub.4 H.sub.3 O 28%(10) NDRTR-5634 CPMCH.sub.3 C.sub.4 H.sub.3 O 14%(10) 3.95MLS-5692 CH.sub.3 CH.sub.3 C.sub.3 H.sub.7 Ia(10) --MLS-5695 CH.sub.3 H C.sub.3 H.sub.7 5.25 --MLS-5682 CH.sub.3 CH.sub.3 C.sub.5 H.sub.11 4.0 --MLS-5689 CH.sub.3 H C.sub.5 H.sub.11 0.76 --MLS-5688H CH.sub.3 CH.sub.3 (CH.sub.2).sub.2C.sub.6 H.sub.5 0.62 --MLS-5690 CH.sub.3 H (CH.sub.2).sub.2C.sub.6 H.sub.5 0.105 --MLS-5683 CH.sub.3 CH.sub.3 (CH.sub.2).sub.3C.sub.6 H.sub.5 0.41 --MLS-5691 CH.sub.3 H (CH.sub.2 ).sub.3C.sub.6 H.sub.5 0.0052 --______________________________________ TABLE II______________________________________ ##STR12## ED.sub.50 AD.sub.50Compound R R.sub.1 R.sub.3 R.sub.2 (mg/kg) (mg/kg)______________________________________TR-5492 CH.sub.3 CH.sub.3 CH.sub.3 CH.sub.3 4.5 --TR-5479 CPM CH.sub.3 CH.sub.3 CH.sub.3 Ia(10) 41%(10)TR-5499 CPM CH.sub.3 CH.sub.3 C.sub.3 H.sub.7 0.42 12%(7)TR-5544 CPM CH.sub.3 CH.sub.3 C.sub.4 H.sub.9 10%(10) Ia(10)TR-5543 CPM H CH.sub.3 C.sub.3 H.sub.7 1.8 2.8TR-5551 CPM H CH.sub.3 C.sub.4 H.sub.9 40%(10) 2.5TR-5538 CPM H CH.sub.3 C.sub.5 H.sub.11 0.28 6.6TR-5572 CPM H CH.sub.3 i-C.sub.3 H.sub.7 7.8 2.2MLS-5694 CH.sub.3 H C.sub.5 H.sub.11 CH.sub.3 2.9 --______________________________________

Claims

1. 4,5.alpha.-epoxy-3-hydroxy or methoxy-7-(1-hydroxyalkyl or 1-oxoalkyl)morphinan-6-one compounds characterized by the structural formulae: ##STR13## wherein R is methyl, cyclopropylmethyl, cyclobutylmethyl, propargyl, allyl, dimethylallyl, cis-chloroallyl or furfuryl; R.sub.1 is H or methyl; R.sub.2 is straight or branched chain alkyl of from 1 to 10 carbon atoms, phenyl or phenylalkyl in which the alkyl chain contains from 1 to 6 carbon atoms, and R.sub.3 is a straight chain alkyl of 1 to 4 carbon atoms.

2. The compounds of claim 1 which are characterized by the formula: ##STR14## wherein R, R.sub.1 and R.sub.2 are as previously defined.

3. A compound as defined by claim 2 wherein R is cyclopropylmethyl, R.sub.1 is H and R.sub.2 is CH.sub.3.

4. A compound as defined by claim 2 wherein R is cyclopropylmethyl, R.sub.1 is CH.sub.3 and R.sub.2 is C.sub.3 H.sub.7.

5. A compound as defined by claim 2 wherein R is cyclopropylmethyl, R.sub.1 is H and R.sub.2 is C.sub.3 H.sub.7.

6. A compound as defined by claim 2 wherein R is cyclopropylmethyl, R.sub.1 is CH.sub.3 and R.sub.2 is i-C.sub.3 H.sub.7.

7. A compound as defined by claim 2 wherein R is cyclopropylmethyl, R.sub.1 is H and R.sub.2 is C.sub.6 H.sub.5.

8. A compound as defined by claim 2 wherein R is cyclopropylmethyl, R.sub.1 is CH.sub.3 and R.sub.2 is C.sub.6 H.sub.5.

9. A compound as defined by claim 2 wherein R is cyclopropylmethyl, R.sub.1 is H and R.sub.2 is C.sub.2 H.sub.5.

10. A compound as defined by claim 2 wherein R is cyclopropylmethyl, R.sub.1 is H and R.sub.2 is C.sub.4 H.sub.9.

11. A compound as defined by claim 2 wherein R is cyclopropylmethyl, R.sub.1 is H and R.sub.2 is C.sub.5 H.sub.11.

12. A compound as defined in claim 2 wherein R is cyclopropylmethyl, R.sub.1 is H and R.sub.2 is C.sub.6 H.sub.13.

13. A compound as defined in claim 2 wherein R is cyclopropylmethyl, R.sub.1 is H and R.sub.2 is i-C.sub.3 H.sub.7.

14. A compound as defined in claim 2 wherein R is CH.sub.3, R.sub.1 is H and R.sub.2 is C.sub.5 H.sub.11.

15. A compound as defined in claim 2 wherein R is CH.sub.3, R.sub.1 is CH.sub.3 and R.sub.2 is (CH.sub.2).sub.2 --C.sub.6 H.sub.5.

16. A compound as defined in claim 2 wherein R is CH.sub.3, R.sub.1 is H and R.sub.2 is (CH.sub.2).sub.2 --C.sub.6 H.sub.5.

17. A compound as defined in claim 2 wherein R is CH.sub.3, R.sub.1 is CH.sub.3 and R.sub.2 is (CH.sub.2).sub.3 --C.sub.6 H.sub.5.

18. A compound as defined in claim 2 wherein R is CH.sub.3, R.sub.1 is H and R.sub.2 is (CH.sub.2).sub.3 --C.sub.6 H.sub.5.

19. The compounds of claim 1 which are characterized by the formula: ##STR15## wherein R, R.sub.1, R.sub.2 and R.sub.3 are as previously defined.

20. A compound as defined by claim 19 wherein R is cyclopropylmethyl, R.sub.1 is H, R.sub.2 is C.sub.3 H.sub.7 and R.sub.3 is CH.sub.3.

21. A compound as defined by claim 19 wherein R is cyclopropylmethyl, R.sub.1 is H, R.sub.2 is C.sub.5 H.sub.11 and R.sub.3 is CH.sub.3.

22. A compound as defined by claim 19 wherein R is cyclopropylmethyl, R.sub.1 is H, R.sub.2 is i-C.sub.3 H.sub.7 and R.sub.3 is CH.sub.3.

23. A compound as defined by claim 19 wherein R.sub.1 is cyclopropylmethyl, R.sub.1 is CH.sub.3, R.sub.2 is C.sub.3 H.sub.7 and R.sub.3 is CH.sub.3.