United States Patent [191
`Stammer
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,954,158
`Sep. 4, 1990
`
`[54] 2,3-ME1‘HANOPROLINE
`[75] Inventor: Charles H. Stanuner, Athens, Ga.
`‘[73] Assignee:
`University of Georgia Research
`Foundation, Inc., Athens, Ga.
`[21] App]. No.: 285,542
`[22] Filed:
`Dec. 15, 1988
`
`[63]
`
`Related US. Application Data
`Continuation-impart of Ser. No. 41,642, Apr. 22, 1987,
`which is a continuation of Ser. No. 879,842, Jun. 26,
`1986, which is a continuation of Ser. No. 636,091, Aug.
`3, 1984, which is a continuation-in-part of Ser. No.
`523,080, Aug. 16, 1983.
`
`[51] Int. Cl.5 .................. .. A01N 43/38; C07D 209/52
`[52] US. Cl. ......................................... .. 71/76; 71/95;
`548/452
`[58] Field of Search .................. .. 548/452, 455; 71/76,
`71/95
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,313,842 4/ 1967 Kaiser et al. .
`4,591,598 5/1986 Urbach .............................. .. 548/452
`4,629,784 12/1986 Stammer .
`OTHER PUBLICATIONS
`Arenal, Bernabe, Fernandez Alveraz, Izquierdo, and
`Penades, J. Heterocyclic. Chem., 20, 607 (1983).
`Bernabe, Cuevas, and Fernandez Alveraz, Eur. J. Med.
`Chem, Chemica Theraputica, 14 (1), 33 (1979).
`Bernabe, Cuevas, and Fernandez Alveraz, “A New
`Synthesis of 1-Amino-2-Arylcyclopropanecarboxylic
`Aci ”, Synthesis 3, 191 (1977).
`Bernabe, Fernandez, and Fernandez Alveraz, Anales de
`Quimica, 75, 977 (1979).
`Bernabe, Fernandez Alveraz, and Ullate, “Derivatives
`of Cyclopropane”, AnaIes de Quimica. 1005 (1972).
`Bregovec and Jakoveic, Monatshete Fur. Chemie, 103,
`288 (1972).
`Elkaschef, Abdel-Megid, and Yassin, Journal F. Prac.
`Chemie, Band 316, Heft 3 (1974), S. 363-368.
`Fowden and Smith, Phythoehemistry, 8, 437 (1969).
`Fujimoto, Irreverre, Karle, Karle, and Whitkop, “Syn
`thesis and X-Ray Analysis of Cis—3,4—Methanoline-L—
`
`Proline, The New Natural Amino Acid from Horse
`Chestnuts, and Its Trans Isomer”, J. Am. Chem. Soc.
`93:14, 3471 (1971).
`Grouiller, Nioche, Varailler, Rouche, and Pacheco,
`Eur. J. Med. Chem, Chemica Theraputica, l5 (2), 139
`(1980).
`Hanzlik, J. Am. Chem. Soc. 104, 2048 (1982).
`Horikawa, Nishitana, Iwosaka, and Inoue, Tet Letters 24
`(21), 2193 (1983).
`Ichihara, Shiraishi, Sakamura, “Partial Synthesis and
`Stereochemistry of Coronatine”, Tet. Letters No. 3, 269
`(1977) and Tet. Letters No. 4, 365 (1979).
`Ichihara, Shiraishi, Sato, Sakamura, Nishimyama, Sa
`kai, Furusaki, and Matsumoto, “The Structure of
`Coronatine”, J. Am. Chem. S. 99:2, 636 (1977).
`Jung and Hudspeth, “Total Synthesis of (:)-Corona
`facic Acid: Use of an Ionic Oxy-Cope Rearrangements
`on Aromatic Substrates in Synthesis”, J. Am. Chem. S.
`102:7, 2463 (1980).
`Kimura and Stammer, “Resolution and Deblocking of
`Racemic
`N-(Benzyloxycarbonyl)
`Cyclopropyl
`phenylalanine”, J. Org. Chem. 48, 2440 (1983).
`King, University of Georgia, Ph.D. Thesis, 1981.
`King, Riordan, Holt, and Stammer, “Synthesis of Race
`mic (E)- and (Z)-l-Amino-Z-Phenylcyclopropane
`Carboxylic Acid: (E)- and (Z)—(Cyclopropylphenylala
`nine)”, J. Org. Chem. 47, 3270 (1982).
`Macinnes, Nonhanbel, Orszulik, and Suckling, J. Chem.
`Soc. Perkin Trans I 2777 (1983).
`(List continued on next page.)
`
`i Primary Examiner-Christine M. Nucker
`Assistant Examiner-Frederick F. Tsung
`‘ Attorney, Agent, or Firm—Kilpatrick & Cody
`
`ABSTRACT
`.
`[57]
`The present invention is 2,3-methanoproline, deriva
`tives thereof, and biologically active molecules incorpo
`‘ rating 2,3-methanoproline. These compounds are useful
`as inhibitors of ethylene production in plant material,
`and as synthetic analogs of biologically active mole
`j cules.
`
`,
`
`2 Drawing Sheets
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`SAXA-DEF-00259
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`Page 1 of 11
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`AstraZeneca Exhibit 2032
` Mylan v. AstraZeneca
` IPR2015-01340
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`

`
`4,954,158
`Page 2
`
`bmE‘ ‘R punucm‘xoss"
`
`‘ Macinnes, Nonhanbel, Orszulik, and Suckling, “Latent
`1 Inhibitors. Part III. The Inhibition of Lactate Dehydro
`genase and Alcohol Dehydrogenase by Propane-Con
`taining Compounds”, J. Chem. Soc. Perkin Trans 1, 2771
`(1983).
`Millington and Sheppard, “Cyclopropane Amino Acids
`from Aesculus and Bligihia”, Phytochemistry 8, 437
`T (1969).
`Nishiyama, Sakai, Ezuka, Ichihara, Shiraishi, and
`‘ Sakamura, “Detection of Coronatine in Halo Blite Lei
`sons in Rye Grass”, Arm. Phytopath. Soc. Japan 43, 219
`(1977).
`Pages and Burger, “l-Amino-Z-(4-ImidazolyD-Cyclo
`propane Carboxylic Acid”, J. Med. Chem, vol. 9, p. 766
`(1966).
`Shiraishi, Ichihara, and Sakamura, f‘Facile?Stereoselec-V
`‘dye. Synthesis of (i)-Allocoronamic Acids”, Agric.
`I Biol. Chem. 41 (12), 2497 (1977).
`I Shiraishi, Konama, Sato, Ichihara, Sakamura, Ni
`shiyama, and Sakai, "The Structure-Activity Relation- 1
`ships in’Coronatine Analogs and Amino Compounds ‘:2
`
`Dmvedrrdm “(i)‘-Coronafacic Acid”, Agric. v19m
`‘Chem.’ 43 (s), 1753 (1979).
`Stewart, “A Synthetic Approach to Peptides of 0- and
`P-Aminobenzoic Acids”, Aust. J. of Chem. 36, 1639
`(1983).
`Stewart, “Peptide Synthesis with l-Amiriocyclo
`propane-l-Carboxylic Acid”, Aust. J. of Chem. 34,
`2431 (1981).
`Bland, Varughese, and Stammer, “Synthesis of (E)—and
`I (Z)-Cyclopropyl-3-Ch1oroalanine”, J. Org. Chem. 49,
`1634 (1984).
`Suzuki, Gooch, and Stammer, “A New Synthesis of
`Racemic Coronamic Acid and Other Cyclopropyl
`Amino Acids”, Tet Letters 24 (36), 3839 (1983).
`Elrod, Holt, Mapelli, and Stammer, “Synthesis of
`2,3-Methano-Glutamic and -Pyroglutamic Acid”, J.
`Chem. Soc, Chemical Communications 252 (1988).
`Bell, Qureshi, Pryce, Jansen, Lemke, and Clardy,
`"2,4—Methanoproline(2-Carboxy—2,4-Methanopyrroli
`dine) and 2,4-Methanoglutamic Acid (l-Amino-l,
`3-Dicarboxycyclobutane) in Seeds of Ateleiaerbert Smi
`thii Pittier (Leguminosae ”, J. Am. Chem. Soc. 102:4
`(1930).
`
`SAXA-DEF-00260
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`SAXA-DEF-00261
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`US. Patent Sep.4, 1990
`
`Sheet 2 of2
`
`4,954,158
`
`7.
`
`5
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`SAXA-DEF-00262
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`Page 4 of 11
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`

`
`1
`
`2,3-METHANOPROLINE
`
`4,954,158
`2
`cyclopropylphenylalanine and its derivatives have
`also been synthesized and studied. King, Riordan, Holt,
`and Stammer, in an article entitled “Synthesis of Race
`mic (E)- and (Z)-1-Amino-2-Phenylcyclopropane Car
`boxylic Acid, (E)- and (Z)-(Cyclopropylphenylala
`nine)”, J. Org. Chem. 47, 3270 (1982), describe the syn
`thesis of both E and Z isomers of D-L-cyclopropyl
`phenylalanine. See also Stephen Wayne King, 1981
`University of Georgia Ph.D Thesis. Kimura and Stam
`mer, in “Resolution and Deblocking of Racemic N
`(Benzyloxycarbonyl) cyclopropylphenylalanine”, J.
`Org. Chem. 48, 2440 (1983), report the isolation of the
`E-diastereomer of cyclopropylphenylalanine from a
`racemic mixture of Z and E. See also Suzuki, Kumar,
`and Stammer, “Use of a New Protecting Group in an
`Attempted Synthesis of Cyclopropyl Dihydroxy
`phenylalanine”, J. Org. Chem. 48, 4769 (1983).
`Additional examples of naturally occurring cyclopro
`pyl amino acids include the diastereomers of a-(2-car
`boxy-cyclopropyD-glycine cyclopropyl)-glycine and
`cis-3,4-methano-L-proline isolated from Aesculus parvi
`?ora and Bliqhia saoida. Fowden, et al., Phytochernis
`try, 8, 437 (1969).
`Fujimoto, Irreverre, Karle, Karle, and Whitkop, in
`“Synthesis and X-Ray Analysis of Cis-3,4-Methanoline
`L-Proline, The New Natural Amino Acid from Horse
`Chestnuts, and Its Trans Isomer”, J. Am. Chem. Soc.
`93:14, 3471 (1971), describe the synthesis of cis- and
`trans-3,4-methano-L-proline. Fujimoto, et al. estab
`lished by x-ray crystallography that the bicyclic system
`approaches a boat conformation both in the cis and the
`trans con?guration. They determined that the boat con
`formation of cis-3,4-methanoline-L-proline is associated
`with the compound’s effect as a powerful competitor
`for proline in the permease system. Z-Piperidine-car
`boxylic acid (D-pipecolinic acid), which has a chair
`conformation, is inactive in these systems.
`The nitrogen atom in proline is part of a rigid satu
`rated ?ve membered ring. Since little rotation about the
`N(proline)-C60 peptide bond is possible when proline is
`incorporated into a peptide chain, proline imparts rigid
`ity to peptides. It would be of chemical and pharmaceu
`tical interest to prepare a cyclopropyl derivative of
`proline in which the cyclopropane ring is connected to
`the a-carbon of this sterically unique amino acid.
`Proline is a key amino acid in many peptide hormones
`due to'its signi?cant effect on the conformation of the
`molecule. Examples of proline containing peptides in
`clude angiotensinogen, angiotensin I, angiotensin II,
`saralasin, capoten, vasotec, lysinopril, bradykinin, thy
`rotropin releasing factor, tuftsin, and melanocyte inhib
`iting factor.
`Angiotensinogen (alternatively called renin substrate
`and hypertensinogen) is the twelve amino acid peptide:
`Asp-Arg-Val-Tyr-Ileu-His-Pro-His-Leu-Val-Tyr. An
`giotensinogen plays a part in hypertension, the eleva
`tion of systolic and/or diastolic blood pressure. Angi
`otensinogen is cleaved at the Leu-Val bond by renin, a
`blood protein, to form angiotensin I (Al). Al is an inac
`tive peptide which is cleaved at the Phe-His bond by
`angiotensinase (or angiotensin converting enzyme
`(ACE)) to form angiotensin II (All). ACE is found in
`the lung, kidney and brain. The octapeptide AII differs
`among animal species only in the amino acid residue in
`position 5, where Val is sometimes found in place of Ile.
`Angiotensin II is a potent vasoconstrictor which also
`stimulates the release of aldosterone, an adrenocortical
`steriod.
`'
`
`45
`
`55
`
`60
`
`5
`
`15
`
`25
`
`30
`
`This application is a Continuation-in-Part of U8. Ser.
`No. 041,642, ?led Apr. 22, 1987 by Charles H. Stammer,
`entitled “The Synthesis of Cyclopropyl Amino Acids
`and Peptides”, which is a Continuation of US. Ser. No.
`879,842, ?led by Charles H. Stammer on June 26, 1986,
`which is a Continuation of U.S. Ser. No. 636,091, ?led
`by Charles H. Stammer on Aug. 3, 1984, which is a
`Continuation-in-Part of US. Ser. No. 523,080, ?led by
`Charles H. Stammer on Aug. 16, 1983, entitled “The
`Synthesis of Cyclopropane Amino Acids.”
`This invention relates to biochemistry, and in particu
`lar to new proline derivatives.
`BACKGROUND OF THE INVENTION
`US. Pat. No. 4,629,784 to Stammer describes the
`synthesis of cyclopropyl amino acids from dehydroala
`nine, and the synthesis of peptides containing cyclopro
`pyl amino acids. The patent is a continuation of US.
`Ser. No. 523,808, to which this invention claims prior
`ity.
`Several amino acids containing cyclopropyl rings
`exist in nature. The simplest cyclopropyl amino acid,
`l-aminocyclopropane-l-carboxylic acid (ACC) has
`been discovered in the fruit of the perry pear and the
`cowberry. Burroughs, J. Sci. Food Agrie. l1 14 (1960). It
`is now known that ACC is a biological precursor to
`ethylene in plants.
`Coronatine, which induces phytotoxic lesions on the
`leaves of Italian rye-grass and hypertrophic growth of
`potato tuber tissue, is the amide of coronafacic acid with
`coronamic acid (l-amino-l-carboxy-Z-ethyl-cyclopro
`pane). Coronatine has been synthesized by various
`groups in whole or part. Shiraishi, Ichihara, and
`Sakamura, “Facile Stereoselective Synthesis of (i)-Al
`locomonamic Acids”, Agric. Biol. Chem. 41 (12), 2497
`(1977) describe the stereoselective synthesis and optical
`resolution of (:t)-Allocoronamic Acid. See also Shirai
`shi, Konoma, Sato, Ichihara, Sakamura, Nishiyama, and
`Sakai, “The Structure-Activity Relationships in
`Coronatine Analogs and Amino Compounds Derived
`From (+)—Coronafacic Acid”, Agric. Biol. Chem. 43 (8),
`1753 (1979); Ichihara, Shiraishi, Sakamura, Tet Letters
`No. 3, 269 (1977) and Tet Letters No. 4, 365 (1979);
`Suzuki, Gcoch, and Stammer, “A New Synthesis of
`Racemic Coronamic Acid and Other Cyclopropyl
`Amino Acids”, Tet Letters 24 (36), 3839 (1983); Jung
`and Hudspeth, “Total Synthesis of (i)-Coronafacic
`Acid: Use of an Ionic Oxy-Cope Rearrangements on
`Aromatic Substrates in Synthesis”, J. Am. Chem. S.
`102:7, 2463 (1980).
`Shiraishi, et al., in “The Structure-Activity Relation
`ships in Coronatine Analogs and Amino Compounds
`Derived From (+)-Coronafacic Acid”, Agric. Biol.
`Chem. 43 (8), 1753 (1979), describe the synthesis of
`several coronatine analogs, and the effect of varying the
`substituents of coronatine on the hypertrophy respon
`sive of potato tubers. Shiraishi, et a1. conclude that the
`presence of the carboxyl group and the con?guration at
`the a-carbon atom in the amino acid are closely related
`to the activity of the peptide. However, the cyclopro
`pane ring in coronatine was found to have no effect on
`the biological activity, as indicated by the comparison
`65
`of the biological activity of l-N-coronafacoylaminocy
`clopropane-L-isoleucine and N-coronafacoyl-D-isoleu
`cine.
`
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`
`4,954,158
`3
`4
`Angiotensin II analogues have been synthesized to
`phenyl wherein the substituents may be F, Cl, Br, I,
`block the All receptor. One is saralasin, SarI-AIaS-AII,
`R9, 0R9, NHRQ, N(R9)2, SR9, S02R9, COR9, Or
`in which sarcosine (N-methylglycine) is substituted for
`C02R9;
`aspartic acid and alanine is substituted for the phenylal
`R3 is H, R9, phenyl or substituted phenyl wherein the
`anine in All.
`substituents may be F, Cl, Br, 1, R9, 0R9, NHR9,
`There are currently at least three proline containing
`N(R9)2, SR9, $02119, COR9, CO2R9;
`ACE inhibitors which prevent the conversion of Al to
`R4 is H, Cl, Br, I, F, 0R3 or OH;
`All. One is capoten (captopril), l-[(2S)-3-mercapto-2~
`methylpropionyl]-L-proline, manufactured by E. R.
`Squibb and Sons, Inc. Another is vasotec (enalapril),
`(S)-l~[N-[l-(ethoxycarbonyl)-3-phenylpropyl1-L
`alanyl]-L-proline manufactured by Merck and Co., Inc.
`Enalapril is the ethyl ester prodrug of enalaprilat. The
`third is lysinopril, (S)-l-[N-(l-(ethoxycarbonyl)-3
`phenylpropyl)-L-lysinyl]-L-proline.
`Proline is also found in bradykinin, a nine amino acid
`peptide:
`Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg.
`Bradykinin acts on smooth muscles, dilates peripheral
`vessels, and increases capillary permeability. Most im
`portantly, bradykinin is a potent pain-producing agent.
`Bradykininase (which is identical to ACE) degrades
`bradykinin in vivo.
`One of the three amino acids of thyrotropin releasing
`hormone (TRF) (pGlu-His-Pro) is proline. TRF stimu
`lates the synthesis and secretion of both thyroid
`stimulating hormone (TSH) and prolactin (PRL).
`Under pathologic conditions TRH may also stimulate
`growth hormone (GI-I) production and release.
`Tuftsin is a naturally occurring tetrapeptide (Thr
`Lys-Pro-Arg) which has a variety of immunopotentiat
`ing properties, such as stimulation and enhancement of
`phagocytosis. It also ‘exhibits antitumor and antibacte
`rial activity.
`Melanostatin, alternatively called melanocyte inhibit
`ing factor (MIF) (L-prolyl-L-leucyl-glycinamide) medi
`ates hypothalamic control of melanotropin, a pituitary
`hormone. MIF is also thought to potentiate DOPA
`induced behavioral changes.
`Given the prevalence and importance of proline in
`biological systems, it would be of great bene?t to pre
`pare Col-C3 cyclopropyl derivatives of proline which
`may be substituted for natural proline in biologically
`active molecules in order to modify the properties of
`the molecules.
`Therefore, it is an object of the present invention to
`prepare a derivative of proline which has a cyclopropyl
`group in the Ca-CB postion. It is a further object of the
`present invention to modify biologically'active mole
`cules by substituting C60‘C3 cyclopropyl derivatives of
`proline for naturally occurring proline or other amino 5o
`acids in the molecule.
`
`R6 and R7 are R; or COR3;
`R3 is R3, R3CO, or R3502; and
`R9 is a straight, branched, or cyclic alkyl group of
`from C1 to C12.
`2,3-Methanoproline and its derivatives inhibit ethyl
`ene production in plant material. They are also useful as
`intermediates in the production of modi?ed biologically
`active molecules.
`The compounds having the general structure set
`forth above can be made by a variety of techniques, for
`example, by reacting a diazo compound with a deriva
`tive of 2,3-dehydroproline, or by intramolecular cycli
`zation of an N-diazoalkyl dehydroalanine derivative,
`followed by pyrolysis or photolysis.
`These compounds have a significantly different struc
`ture than, and exhibit significantly different properties
`from, the cyclopropyl amino acids known to date.
`
`BRIEF DESCRIPTION OF THE FIGURES
`FIG. 1 is an illustration of Scheme 1 for the synthesis
`of 2,3—methanoproline or its derivatives in which a
`diazo compound is reacted with a derivative of 2,3
`dehydroproline to form a proline derivative, in accor
`dance with the present invention.
`FIG. 2 is an illustration of Scheme 2 for the synthesis
`of 2,3-methanoproline or its derivatives in which an
`N-diazoalkyl dehydroalanine derivative is cyclized in
`tramolecularly, and ‘then pyrolyzed or photolyzed to
`form a proline derivative, in accordance with the pres
`ent invention.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`The present invention is a compound of the general
`structure
`
`R7
`
`c-nz
`II
`0
`
`R5
`
`N
`|
`R1
`
`SUMMARY OF THE INVENTION
`The present invention is a compound of the general
`structure
`
`R4
`
`R3
`
`R5
`
`N
`|
`R1
`
`R6
`R7
`
`C-Rz
`II
`0
`
`wherein:
`R1 is H, R9, COR3, CO2R3, SO2R3, or 65
`R3CH(NH2)CO-;
`R2 is H, R9, 0R3, OH, Cl, Br, F, I, NHZ, NHR3,
`N(R3)2, benzyl, phenyl or substituted benzyl or
`
`wherein:
`R1 is H, R9, COR3, CO2R3, SO2R3, OI‘
`R3CH(NH2)CO-;
`R2 is H, R9, 0R3, OH, Cl, Br, F, I, NH2, NHR3,
`N(R3)2, benzyl, phenyl or substituted benzyl or
`phenyl wherein the substituents may be F, Cl, Br, I,
`R9, 0R9, NHR9, N(R9)2, SR9, S02R9, C0R9, 0r
`C02R9;
`R3 is H, R9, phenyl or substituted phenyl wherein the
`substituents may be F, Cl, Br, I, R9, 0R9, NHR9,
`N(R9)2, SR9, $02119, COR9, C02R9;
`R4 is H, Cl, Br, I, F, CR3 or OH;
`R5 is R3 or :0
`R6 and R7 are R3 01' COR3;
`
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`4,954,158
`6
`5
`Chem. 45, 5377 (1980), incorporated herein by refer
`R9 is a straight, ‘branched, or cyclic alkyl group of
`from C1 to C12.
`ence.
`The N-carbobenzyloxy group is then removed from
`The compounds of the present invention inhibit eth
`compound (5) by reduction with H; and palladium on
`ylene production in plant material, for example, strips of
`carbon as the catalyst, or, alternatively, using tri?uoro
`cucumber cotyledons and germinating squash seeds. In
`acetic acid with thioanisole or hydrogen bromide in
`addition, 2,3-methaneproline and its derivatives are
`acetic acid.
`useful in the modi?cation of biologically active com
`The alkyl or aryl ester of the 2,3-methanopyrrolidine
`pounds.
`Z-carboxylate (5) may then be removed by acidic or
`The compounds of the present invention have a sig
`basic hydrolysis to form the target compound, 2,3
`ni?cantly different structure than and exhibit signi?
`methanoproline (1). If an acid such as HCl is used to
`cantly different properties from the cyclopropyl amino
`remove the ester, the corresponding ammonium salt is
`acids known to date. 2,3-methanoproline cannot exist in
`formed. The free .base may be generated by, for exam
`a chair conformation, as does 3,4-methanoproline. Fur
`ple, passing a solution of the compound through a basic
`ther, the cyclopropyl group in 2,3-methanoproline may
`ionic exchange resin. Alternatively, it may be removed
`act as a suicide substrate for enzymes which catalyze
`by treatment with a basic solution followed by acidi?
`reactions in the area of the amide bonds of the peptide.
`cation to the isoelectric point.
`This enzyme inactivation route is unavailable in 3,4
`Derivatives of 2,3-methanopyrrolidine-2-carboxylic
`methanoproline, because the cyclopropyl group is
`acid having N-acyl groups other than benzyloxycarbo
`bound at the Ca-C-y position.
`nyl in the R1 position are prepared by reacting com
`The compounds having the general structure set
`pound (3) with C1CO2R3 or acetyl or benzoyl chloride,
`forth above may be made by a variety of methods, in
`and then proceeding with the synthetic steps described
`cluding reacting a diazo compound with a derivative of
`above. Alternatively, 2,3-methanoproline may be re
`2,3-dehydroproline (Scheme 1) or intramolecular cycli
`acted with an alkyl halide to produce the corresponding
`zation of an N-diazoalkyl dehydroalanine derivative
`N-alkyl-2,3-methanoproline. This reaction occurs by
`followed by pyrolysis or photolysis (Scheme 2).
`simply mixing the alkyl halide with compound (1) at
`room temperature or if necessary in the presence of a
`Scheme 1
`base such as potassium carbonate. The R1 sulfonamide
`A ?rst method of synthesis of 2,3-methanoproline and
`derivative may be prepared by reacting an AISO2C1 or
`its derivatives, referred to herein as Scheme 1, is illus
`R9SO2Cl with compound (6). The carboxylic acid ester
`trated in FIG. 1. In step 1 of Scheme 1, the alkyl or aryl
`is then removed by treatment with an alkali solution.
`ester of proline (2) is oxidized to the corresponding
`' Derivatives of 2,3-methanoproline which have a
`1,2‘dehydroproline ester (alkyl or aryl 1,2-dehydro-pyr
`halogen (Cl, Br, F, I) in the R2 position may be prepared
`rolidine-Z-carboxylate) (3). This reaction may be ac
`by reacting the N-acyl 2,3-methanoproline derivative
`complished with a variety of oxidizing reagents, for
`with thionyl chloride, phosphorous trichloride, phos
`example, tert-butylhypochlorite, sodium hypochloritc, V
`phorous pentachloride, phosphorous tribromide, or
`manganese dioxide, mercuric oxide and other mild oxi
`phosphorous triiodide. This reaction may be performed
`dizing agents. The reaction is done in an organic sol
`in chloroform, methylene chloride, or other common
`vent, for example, ether, methylene chloride, chloro
`organic solvents, in a temperature range of 0° to 80° C.
`form, ethyl acetate, dimethyl formamide, or acetoni
`The acid chloride produced may be reacted with .am
`trile, at —50° C. to 80° C. When tert-butylhypochlorite
`monia or an amine to produce the corresponding amide.
`'is used, after the reaction is completed, the reaction
`Desired alkyl or aryl esters of 2,3-methanoproline may
`mixture is stirred with an excess of triethylamine to
`be prepared by reacting the N-acyl 2,3-methanoproline
`eliminate hydrogen chloride, giving a 1,2-dehydropro
`acid halide derivative with the desired alcohol or phe
`line ester.
`nol, according to procedures known to those skilled in
`In the second step of Scheme 1, the ester of 1,2-dehy
`the art.
`droproline (3) is reacted with benzyl chloroformate in
`In a variation of Scheme 1, an ester of pyroglutamic
`the presence of a tertiary amine such as triethylamine or
`acid may be substituted for the ester of pyrrolidine-Z
`pyridine to produce the ester of N-carbobenzyloxy-2,3
`carboxylate (2) in the ?rst step of the reaction sequence.
`dehydroproline (alkyl or aryl N-carbobenzyloxy-2,3
`The remaining steps of the synthetic scheme may be
`dehydro-pyrrolidine-Zcarboxylate) (4). This reaction is
`carried out as described above.
`conducted at a temperature range from 50° C. to 50° C.
`When the compounds of the present invention are
`in organic solvents such as ether, methylene chloride,
`prepared from pyroglutamic acid, the ?nal product, as
`acetonitrile or ethyl acetate. Suitable substitutes for
`well as the intermediates, have a carbonyl group in the
`benzyl chloroformate include t-butoxycarbonyl chlo
`R5 position. An advantage of this procedure to prepare
`ride, p-methoxy- or p-nitro~benzyloxycarbonyl chlo
`the compounds of the present invention is that pyro
`glutamic acid is an inexpensive starting material, well
`ride, or acetyl or benzoyl chloride.
`In the third step of Scheme 1, alkyl or aryl N-car
`suited for commercial scale reactions. Reduction of the
`bobenzyloxy-Z,3-dehydro-pyrrolidine-2‘carboxylate (4)
`carbonyl group by methods known to those skilled in
`the art, for example, as described in K. Dranz, et al., J.
`is reacted with diazomethane or a substituted diazo
`Org. Chem. 57, 3494 (1986), provides compound (1) or a
`_ methane to produce the alkyl or aryl ester of N-car
`bobenzyloxy-Z,S-methanopyrrolidine-2~carboxylate (5).
`derivative thereof.
`The chemical reactions described for Scheme 1 and
`The substituents on the carbon atom of diazomethane
`determine the substituents R6 and R7 in the proline de
`Scheme 2 are generally disclosed in terms of their
`broadest application for the preparation of the com
`rivative of the present invention. Diazomethane or a
`pounds of this invention. Modi?cations of the general
`substituted diazomethane is generated under nitrogen in
`situ, by methods generally known to those skilled in the
`methods may be required in the synthesis of some com
`pounds using techniques known to those skilled in the
`art, for example, as described in M. Hudlicky, J. Org.
`
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`7
`art, for example, by appropriate protection of interfer
`colorless solution of crude pyrazoline which was con
`ing groups, by changing to alternative conventional
`centrated and photolyzed for 4 hours in CH2Cl2 (500
`reactions, by routine modi?cation of reaction condi
`ml) in an ice-water cooled apparatus using a 450 W
`Hanovia medium-pressure mercury lamp. The crude
`tions, or other reactions disclosed herein or otherwise
`conventional. In all preparative methods, all starting
`2,3-methanopyrrolidine from these three runs was then
`chromatographed in two portions on silica gel (230-400
`materials are known or are readily prepared from
`known starting materials.
`mesh, 65><270 mm column, hexanes to 1:1 hexanes
`The following speci?c working examples of Scheme
`/ethyl acetate gradient elution) to afford 16.4 g (65%)
`of compound (5) as a colorless oil; 1H NMR (CDC13)
`1 are, therefore, to be construed as merely illustrative,
`87.21 (s, 5H), 5.07 (s, 2H), 3.4-4.1 (m, 2H), 1.6-2.4 (m,
`and are not intended to limit the disclosure in any way.
`4H), 1.47 (s, 9H), 0.97 (br s, 1H) ppm; 13C NMR
`t-Butyl l,2-dehvdropyrrolidine-2-carboxylate (3)
`(CDC13): 8169.5, 155.7, 136.54, 128.2, 127.5, 80.9, 66.8,
`51.4 (br), 48.2, 30.5 (br), 27.7, 26.5, 26.0 (br) ppm.
`To 100 ml of ether at —20° C. were added simulta
`neously t-butyl pyrrolidine-Z-carboxylate (6.8 g, 4.0
`t-Butyl 2,3-Methanopyrrolidine-Z-carboxylate (6)
`mmol) and freshly prepared tert-butyl-hypochlorite (4.8
`Compound (5) was dissolved in ethyl acetate (300 ml)
`ml, 40 mmol) dropwise over a 15 minute period. The
`and the solution was ?ushed with argon. Palladium-on
`cold bath was then removed and the mixture was stirred
`for 30 minutes after which triethylamine (5.6 ml, 40
`carbon (5%, 3 g) was added and hydrogen was bubbled
`mmol) was added. A white precipitate quickly formed
`into the stirred suspension until no starting material
`remained (2 hours as indicated by TLC). The ?ask was
`and the suspension was stirred at room temperature for
`40 hours. The precipitate was ?ltered and washed with
`then ?ushed with nitrogen and the catalyst was re
`moved by ?ltration. The catalyst was washed with
`ether (2X 50 ml). The ?ltrate was concentrated and the
`residue was distilled with a Kuglerohr apparatus to give
`methanol (3x100 ml) and the combined ?ltrates were
`compound (3) (6.0 g, 89%) as a colorless oil:
`concentrated. The residue was then distilled with a
`bp=55°—70°/0.3 torr. 1H NMR (CDC13): 3.9-4.2 (m,
`Kuglerohr apparatus at reduced pressure to give 6.6 g
`2H), 2.6-2.9 (m, 21-1), 18-21 (m, 2H), 1.52 (s, 9H) ppm.
`(85%) of compound (6) as a light yellow oil:
`bp=90°-120° C./O.8 mm; 1H NMR (C6D6): 82.83 (m,
`t-Butyl
`1H), 2.32 (m, 1H), 2.10 (br s, 1H), 1.76 (m, 1H), 1.31-1.65
`N-carbobenzyloxy-Z,3—dehydropyrrolidine-Z-carboxy
`(m, 3H), 1.36 (s, 9H), 0.85 (t, J =6 Hz) ppm. 13NMR
`late (4)
`(C6D6) 8172.2 (C=O , 80.1 (quat), 50.1 (quat), 44.3
`To a_ stirred solution of compound (3) (16.0 g, 94.8
`(CH2), 28.1 (Cl-l2), 27.7 (CH), 16.7 (CH2) ppm.
`mmol) and pyridine (12 ml, 150 mmol) in CH2C12 (100
`2,3-Methanopyrrolidine-2-carboxylic acid (1)
`ml) at —20° C. was added benzyl chloroformate (21.4
`(2,3-Methanoproline)
`ml, 150 mmol) dropwise over a 15 minute period. The
`Distilled compound (6) (4.4 g, 24 mmol) and anisole
`solution was stirred at room temperature overnight.
`N,N-Diethylethylenediamine (14 ml, 100 mmol) was
`(3.0 ml, 28 mmol) were dissolved in 3.0 M HCl in diox
`then added dropwise over 15 minutes to destroy the
`ane (40 ml) and the solution was stirred at room temper
`ature overnight. A white precipitate formed. The sus
`excess chloroformate and the reaction was stirred for an
`pension was diluted with hexanes (200 ml). The precipi
`additional 2 hours. The solution was then diluted with
`CH2C12 (300 ml) and washed with 10% aqueous citric
`tate was ?ltered and washed with ether (2x100 ml).
`The solid was then dissolved in isopropanol (100 ml)
`acid (2X 300 ml) and 10% aqueous Na2CO3 (300 ml).
`and reprecipitated with ether (800 ml) to give a light
`The organic phase was dried (K2CO3), concentrated,
`and chromatographed on silica gel (230-400 mesh,
`orange solid which was chromatographed on reverse
`phase silica gel (10 g, 40 um ?ash chromatography
`65 X 270 mm column, 3 portions, hexanes to 6:4 hexanes
`/ethyl acetate gradient elution) to produce 22.4 g (78%)
`grade C18, water). The aqueous solution was then ly
`45
`ophilized and the yellow-white solid was recrystallized
`of compound (4) as a colorless oil; 1H NMR (CDC13):
`from isopropanol/ether. After the initial precipitation
`87.21 (s, 5H), 5.68 (t, 1H, J =3 Hz), 5.08 (s, 2H) 3.91 (t,
`2H, J +Hz), 2.57 (d of t, 2H, J =9 Hz, J=Hz), 1.40 (s,
`of a small amount of highly colored material, the amino
`acid hydrochloride hydrate (compound (2), 3.2 g, 73%)
`9H) ppm; 13C NMR (CDC13): 8160 1.8, 153.4, 137.6,
`was isolated as granular white crystals: mp=200°-215°
`36.0, 128.3, 128.0, 119.1, 81.8, 67.3, 48.6, 28.3, 27.8 ppm.
`C.; 13C NMR (D20): 8171.5, 46.7, 43.2, 27.0, 24.6, 14.9
`t-Butyl
`ppm; MSzm/e 127 (M+),l09 (M—H2O).
`N-carbobenzyloxy-2,3-methanopyrrolidine—2-carboxy
`Anal. Calcd. for C6H9NO2.HCl.H2O: C, 39.67%; H,
`late (5)
`6.66%; N, 7.74%. Found: C, 39.73%; H, 6.72%; N,
`7.68%.
`Compound (4) (24.0 g, 79.2 mmol) was divided into
`three equal portions and each portion was treated with
`The zwitterion of (l) was prepared from its hydro
`chloride salt by stirring an aqueous solution of the salt
`excess diazomethane. Each batch of diazomethane was
`generated under nitrogen from N-methyl-N-nitroso
`with Dowex lX8-50-acetate (50 g) overnight at room
`para-toluenesulphonamide (Diazald, 32 g, 150 mmol) by
`temperature. The resin was removed by ?ltration and
`washed with water (3 X100 ml). The combined ?ltrates
`methods known to those skilled in the art, as, for exam
`ple, described by M. Hudlicky, J. Org. Chem. 45, 5377
`were lyophilized to afford the desired zwitterion (1 7 g,
`(1980). The resulting diazomethane/ether mixture was
`53% from compound (6)) as a white powder:
`mp= l97°-203° C.; 1H NMR (D20): 83.58 (m, 1H), 3.06
`collected with a Dry Ice/CCl4 cooled condenser and
`(m, 1H), 2.1-2.5 (m, 3H), 1.3-1.8 (m, 2H) ppm; 13C
`added directly to a Dry Ice/CCl4 cooled solution of
`compound (4) in CHgClz (100 ml). This solution was
`NMR (D20): 8173.9, 48.8, 41.2, 24.8, 13.2 ppm.
`65
`Anal. Calcd. for céHgNOzi H2O: C, 54.72%; H,
`then stirred at room temperature for 24 hours after
`6.89%; N, 10.68%. Found: C, 54.6%; H, 7.30%; N,
`which CaClg (10-20 g) was added and stirring was con
`10.55%.
`tinued for 16 hours. The CaClz was ?ltered to give a
`
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`9
`Scheme 2
`A second method of synthesis of 2,3-methanoproline
`and its derivatives, referred to herein as Scheme 2, is
`illustrated in FIG. 2. The N-alkylated dehydroalanine
`derivative (7) is prepared by N-alkylation of a dehy
`droalanine derivative using an appropriate alkyl halide
`in acetone and powdered potassium carbonate. Treat
`ment of (7) with nitrous acid followed by a strong base
`generates the diazo compound (8) which spontaneously
`cyclizes to a pyrazoline which is then photolyzed with
`out isolation to give the cyclopropane (6). This is then
`converted into 2,3-methanoproline by procedures de
`scribed in Scheme 1 or other methods known to those
`skilled in the art. The following example is merely illus
`trative of the method of Scheme 2, and is not meant to
`limit the scope of the invention.
`t-Butyl-N-benzyloxycarbonyl-2,3-methanopyrrolidine
`(5)
`20
`A suspension of 3 mmole of compound (7) in 25 ml of
`water is treated with 1.1 equivalents of solid sodium
`nitrite followed by 5-10 mL of acetic acid. Ether (