메뉴 건너뛰기




Volumn 72, Issue 25, 2007, Pages 9648-9655

Stereoselective synthesis of a MCHr1 antagonist

Author keywords

[No Author keywords available]

Indexed keywords

BENZYLPIPERIDONE; DIASTEREOMERS; MELANIN-CONCENTRATING HORMONE (MCH); STEREOSELECTIVE SYNTHESIS;

EID: 36849056087     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo701894v     Document Type: Article
Times cited : (27)

References (56)
  • 6
    • 36849005369 scopus 로고    scopus 로고
    • Sherman, L. P.; Camacho, R. E.; Sloan, S. D.; Zhou, Bednarek, M. A.; Hereniuk, D. L.; Feighner, S. D.; Tan, C. P.; Howard, A. D.; Van der Ploeg, L. H.; MacIntyre, D. E.; Hickey, G. J.; Strack, A. M. Eur. J. Pharmacol. 2003, 15, 475.
    • (d) Sherman, L. P.; Camacho, R. E.; Sloan, S. D.; Zhou, Bednarek, M. A.; Hereniuk, D. L.; Feighner, S. D.; Tan, C. P.; Howard, A. D.; Van der Ploeg, L. H.; MacIntyre, D. E.; Hickey, G. J.; Strack, A. M. Eur. J. Pharmacol. 2003, 15, 475.
  • 24
    • 0015726219 scopus 로고
    • For an alternative strategy for the formation of a similar, tetracyclic isoquinolinone system, see
    • For an alternative strategy for the formation of a similar, tetracyclic isoquinolinone system, see: Le Goffic, F.; Gouyetts, A.; Ahoud, A. Tetrahedron 1973, 29, 3357.
    • (1973) Tetrahedron , vol.29 , pp. 3357
    • Le Goffic, F.1    Gouyetts, A.2    Ahoud, A.3
  • 26
    • 36849008529 scopus 로고    scopus 로고
    • Annulation of N-methyl-4-piperidone with pentenone was reported to give the N-Me analogue of 9. However, the stereochemistry was not defined, see: (a) Bergman, J.; Goonewardena, H. Acta. Chem. Scand. Ser. B 1980, 34, 763.
    • Annulation of N-methyl-4-piperidone with pentenone was reported to give the N-Me analogue of 9. However, the stereochemistry was not defined, see: (a) Bergman, J.; Goonewardena, H. Acta. Chem. Scand. Ser. B 1980, 34, 763.
  • 27
    • 8344283809 scopus 로고
    • For the reaction of 2-methylcyclohexanones with pentenone, see: b
    • For the reaction of 2-methylcyclohexanones with pentenone, see: (b) Kikughi, M.; Yoshikoshi, A. Bull. Chem. Soc. Jpn. 1981, 54, 3420.
    • (1981) Bull. Chem. Soc. Jpn , vol.54 , pp. 3420
    • Kikughi, M.1    Yoshikoshi, A.2
  • 29
    • 0023874857 scopus 로고    scopus 로고
    • Robinson annulation of cyclohexanone with β-aryl methyl vinyl ketones has been reported but the stereochemistry was not defined, see: (d) Eiden, F, Gmeiner, P. Arch. Pharm. 1988, 321, 397
    • Robinson annulation of cyclohexanone with β-aryl methyl vinyl ketones has been reported but the stereochemistry was not defined, see: (d) Eiden, F.; Gmeiner, P. Arch. Pharm. 1988, 321, 397.
  • 33
    • 36849056980 scopus 로고    scopus 로고
    • The reaction was monitored by gas chromatography for the consumption of N-benzyl-4-piperidone. It was critical to the success of this process to leave <2.5% of the starting material at this stage.
    • (c) The reaction was monitored by gas chromatography for the consumption of N-benzyl-4-piperidone. It was critical to the success of this process to leave <2.5% of the starting material at this stage.
  • 34
    • 36849059590 scopus 로고    scopus 로고
    • 1H NMR. It was essential to check the quality of the 3-penten-2-one used carefully. A thorough analytical analysis revealed that it can contain variable amounts of acetic acid and water. These impurities caused hydrolysis of enamine 8, regenerating N-benzyl-4-piperidone, which lowered the yield of the tartrate salt dramatically. Experimentation revealed that <0.10 wt % of acetic acid and <1.0 wt % of water were tolerated.
    • 1H NMR. It was essential to check the quality of the 3-penten-2-one used carefully. A thorough analytical analysis revealed that it can contain variable amounts of acetic acid and water. These impurities caused hydrolysis of enamine 8, regenerating N-benzyl-4-piperidone, which lowered the yield of the tartrate salt dramatically. Experimentation revealed that <0.10 wt % of acetic acid and <1.0 wt % of water were tolerated.
  • 35
    • 36849079735 scopus 로고    scopus 로고
    • The structures were surmised by the GC/MS and literature precedent, see: Stork, G.; Brizzolara, A.; Landesman, H.; Szmuskovicz, J.; Terrell, R. J. Am. Chem. Soc. 1963, 55, 207. All the intermediates were converted to the enone after addition of acetic acid.
    • The structures were surmised by the GC/MS and literature precedent, see: Stork, G.; Brizzolara, A.; Landesman, H.; Szmuskovicz, J.; Terrell, R. J. Am. Chem. Soc. 1963, 55, 207. All the intermediates were converted to the enone after addition of acetic acid.
  • 36
    • 36849053294 scopus 로고    scopus 로고
    • The amount of piperidone was detrimental to the isolated yield of the tartrate salt of 9. With > 10% of N-benzyl-4-piperidone, the resolution yield of 9 dropped from 28% overall yield to <12%, and in some cases, the tartrate salt failed to crystallize. In the event that the N-benzyl-4-piperidone was outside the set specification, unreacted material could be removed by washing the crude enone mixture with 1 M aqueous citric acid at pH 5.4.
    • The amount of piperidone was detrimental to the isolated yield of the tartrate salt of 9. With > 10% of N-benzyl-4-piperidone, the resolution yield of 9 dropped from 28% overall yield to <12%, and in some cases, the tartrate salt failed to crystallize. In the event that the N-benzyl-4-piperidone was outside the set specification, unreacted material could be removed by washing the crude enone mixture with 1 M aqueous citric acid at pH 5.4.
  • 37
    • 36849073057 scopus 로고    scopus 로고
    • A second slurry in 80% ethanol/water could upgrade the material to 98.5% ee, if required. However, material of >96% ee will produce isoquinolinone 6 with >99% ee in the subsequent transformations.
    • A second slurry in 80% ethanol/water could upgrade the material to 98.5% ee, if required. However, material of >96% ee will produce isoquinolinone 6 with >99% ee in the subsequent transformations.
  • 38
    • 36849048139 scopus 로고    scopus 로고
    • Minor amounts of the other diastereomers 6a and 6b were rejected in the filtrate. Compounds 6a and 6b were each isolated in ∼0.25% yield by chromatography and identified by 1H NMR. The remaining isomer 6c was not isolated. The structure of 6c was assumed based on the mass obtained from mass spectrometry and retention time comparison to the three characterized isomers 6, 6a, and 6b. The stereochemistry of the methyl group was key to the selectivity in the hydrogenation to produce the anti-relationship between me two bridgehead positions. For comparison, the des-methyl-N-benozyl analogue of 9 was converted to a mixture of the syn,anti-isomers: Rastogi, S. N, Bindra, J. S, Rai, S. N. Indian J. Chem. 1972, 10, 673
    • 1H NMR. The remaining isomer 6c was not isolated. The structure of 6c was assumed based on the mass obtained from mass spectrometry and retention time comparison to the three characterized isomers 6, 6a, and 6b. The stereochemistry of the methyl group was key to the selectivity in the hydrogenation to produce the anti-relationship between me two bridgehead positions. For comparison, the des-methyl-N-benozyl analogue of 9 was converted to a mixture of the syn,anti-isomers: Rastogi, S. N.; Bindra, J. S.; Rai, S. N. Indian J. Chem. 1972, 10, 673.
  • 41
    • 32344442706 scopus 로고    scopus 로고
    • The Fischer-indolization of analogous decalinone systems has been reported to be selective for the formation of the linear isomer over the angular isomer: (a) Miller, F. M, Lohr, R. A, Jr. J. Am. Chem. Soc. 1978, 43, 3388
    • The Fischer-indolization of analogous decalinone systems has been reported to be selective for the formation of the linear isomer over the angular isomer: (a) Miller, F. M.; Lohr, R. A., Jr. J. Am. Chem. Soc. 1978, 43, 3388.
  • 44
    • 36849070251 scopus 로고    scopus 로고
    • At temperature of >72°C there was significant glass erosion from HF evolution >1.5 mg/m3
    • 3).
  • 47
    • 36849064637 scopus 로고    scopus 로고
    • The formaldehyde from the ozonolysis of compound 17 was not easily separated. Despite wiped-film distillation of aldehyde 3 [see: (a) Cvengroš, J.; Valko, M.; Pollák, S.; Lutišan, J. Chem. Papers 1999, 53, 417] small amounts of formaldehyde always contaminated the product, which over time produced other byproducts. Aldehyde 3 was also prone to air oxidation.
    • The formaldehyde from the ozonolysis of compound 17 was not easily separated. Despite wiped-film distillation of aldehyde 3 [see: (a) Cvengroš, J.; Valko, M.; Pollák, S.; Lutišan, J. Chem. Papers 1999, 53, 417] small amounts of formaldehyde always contaminated the product, which over time produced other byproducts. Aldehyde 3 was also prone to air oxidation.
  • 48
    • 36849038848 scopus 로고    scopus 로고
    • To improve stability, 1000 ppm of triefhanolamine [see: (b) Ishihara, T, Yamamoto, A, Ohshima, M, Aiba, N. Patent EP 0148648
    • To improve stability, 1000 ppm of triefhanolamine [see: (b) Ishihara, T.; Yamamoto, A.; Ohshima, M.; Aiba, N. Patent EP 0148648.
  • 49
    • 36849047700 scopus 로고    scopus 로고
    • Weber, J.; Falk, V.; Kniep, C. Patent DE 2917789] was added to the distilled product, which was isolated in 78% yield and >95% purity as a light yellow oil. In contrast, no formaldehyde was generated in the ozonolysis of intermediate 18 to aldehyde 3. Material prepared from this route was free of side products and was isolated in >95% yield and >99% GC purity without the need for wiped-film distillation. As mentioned, one problem with using the aldehyde 3 derived from 17 was the presence of small amounts of formaldehyde. This led to me formation of the N-Me derivative 19. This impurity could be avoided by using 3 prepared from 18.
    • (c) Weber, J.; Falk, V.; Kniep, C. Patent DE 2917789] was added to the distilled product, which was isolated in 78% yield and >95% purity as a light yellow oil. In contrast, no formaldehyde was generated in the ozonolysis of intermediate 18 to aldehyde 3. Material prepared from this route was free of side products and was isolated in >95% yield and >99% GC purity without the need for wiped-film distillation. As mentioned, one problem with using the aldehyde 3 derived from 17 was the presence of small amounts of formaldehyde. This led to me formation of the N-Me derivative 19. This impurity could be avoided by using 3 prepared from 18.
  • 50
    • 36849050635 scopus 로고    scopus 로고
    • 3 prior to the reducing agent, acetal formation was prevented.
    • 3 prior to the reducing agent, acetal formation was prevented.
  • 51
    • 0015512524 scopus 로고    scopus 로고
    • Direct alkylation of carboxylic acids has been reported previously: (a) Creger, P. L. J. Org. Chem. 1972, 37, 1907.
    • Direct alkylation of carboxylic acids has been reported previously: (a) Creger, P. L. J. Org. Chem. 1972, 37, 1907.
  • 56
    • 36849067342 scopus 로고    scopus 로고
    • Only alcohol solvents performed well in this reaction. The N-ethyl byproduct of 2 was observed in ethanol due to the generation of acetaldehyde from oxidation of the solvent. Fortunately, isopropanol resulted in <1% of the corresponding N-alkylated byproduct. In t-BuOH and sec-BuOH the reactions were prohibitively sluggish.
    • Only alcohol solvents performed well in this reaction. The N-ethyl byproduct of 2 was observed in ethanol due to the generation of acetaldehyde from oxidation of the solvent. Fortunately, isopropanol resulted in <1% of the corresponding N-alkylated byproduct. In t-BuOH and sec-BuOH the reactions were prohibitively sluggish.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.