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Volumn 73, Issue 4, 2008, Pages 1578-1581

Michael reactions of titanium enolates of glycolic acid derivatives with the Weinreb and morpholine amides of acrylic acid

Author keywords

[No Author keywords available]

Indexed keywords

ADDITION REACTIONS; AMIDES; DERIVATIVES; ORGANIC ACIDS; REACTION KINETICS;

EID: 39349110573     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo702240n     Document Type: Article
Times cited : (18)

References (38)
  • 4
    • 39349115816 scopus 로고    scopus 로고
    • Li and Na enolates of type 3, when the temperature is raised up to -30°C to increase the reaction rates, begin to decompose.
    • Li and Na enolates of type 3, when the temperature is raised up to -30°C to increase the reaction rates, begin to decompose.
  • 6
    • 0026553741 scopus 로고
    • application to the total synthesis of calyculin
    • (b) Evans, D. A.; Gage, J. R.; Leighton, J. L.; Kim, A. S. J. Org. Chem. 1992, 57, 1961 (application to the total synthesis of calyculin).
    • (1992) J. Org. Chem , vol.57 , pp. 1961
    • Evans, D.A.1    Gage, J.R.2    Leighton, J.L.3    Kim, A.S.4
  • 7
    • 39349113234 scopus 로고    scopus 로고
    • Ph.D. Thesis, Universitat de Barcelona
    • (c) Mas, G. Ph.D. Thesis, Universitat de Barcelona, 2000.
    • (2000)
    • Mas, G.1
  • 8
    • 0033452058 scopus 로고    scopus 로고
    • For the reaction of enolates of trisubstituted oxazolidinones with nitroalkenes, see
    • (d) For the reaction of enolates of trisubstituted oxazolidinones with nitroalkenes, see: Brenner, M.; Seebach, D. Helv. Chim. Acta 1999, 82, 2365.
    • (1999) Helv. Chim. Acta , vol.82 , pp. 2365
    • Brenner, M.1    Seebach, D.2
  • 9
    • 0001449876 scopus 로고    scopus 로고
    • 3-substituted acrylates, see: Shinohara, N.; Haga, J.; Yamazaki, T.; Kitazume, T.; Nakamura, S. J. Org. Chem. 1995, 60, 4363.
    • 3-substituted acrylates, see: Shinohara, N.; Haga, J.; Yamazaki, T.; Kitazume, T.; Nakamura, S. J. Org. Chem. 1995, 60, 4363.
  • 10
    • 39349099236 scopus 로고    scopus 로고
    • 8O). The results were parallel to those reported here.
    • 8O). The results were parallel to those reported here.
  • 11
    • 0023885132 scopus 로고    scopus 로고
    • The TBS protecting group was chosen in view of its stability under the reaction conditions and the availability of specific cleavage methods. The OBn derivative decomposes before reacting, under similar conditions. The synthetic utility of the enolates of glycolate-derived oxazolidinones in other reactions, such as aldol reactions and alkylations, has been established: (a) Evans, D. A, Bender, S. L, Morris, J. J. Am. Chem. Soc. 1988, 110, 2506
    • The TBS protecting group was chosen in view of its stability under the reaction conditions and the availability of specific cleavage methods. The OBn derivative decomposes before reacting, under similar conditions. The synthetic utility of the enolates of glycolate-derived oxazolidinones in other reactions, such as aldol reactions and alkylations, has been established: (a) Evans, D. A.; Bender, S. L.; Morris, J. J. Am. Chem. Soc. 1988, 110, 2506.
  • 16
    • 39349116696 scopus 로고    scopus 로고
    • 4 was dissolved in phosphate-buffered water (pH 8); the reaction time was shortened to 30 min. Migration of the TBS group to the primary hydroxy group did not occur under these conditions.
    • 4 was dissolved in phosphate-buffered water (pH 8); the reaction time was shortened to 30 min. Migration of the TBS group to the primary hydroxy group did not occur under these conditions.
  • 19
    • 39349097232 scopus 로고    scopus 로고
    • Also see ref 1b for complex substrates where undesired conjugate additions can take place
    • (c) Also see ref 1b for complex substrates where undesired conjugate additions can take place.
  • 22
    • 27844466269 scopus 로고    scopus 로고
    • The direct reduction of Weinreb amides to aldehydes is a standard. Since the pioneering work of Nahm and Weinreb (Nahm, S.; Weinreb, S. M. Tetrahedron Lett. 1981, 22, 3815), ca. 200 out of 500 papers have utilized DIBALH as the reducing agent, according to a SciFinder-based search, (b) Very often R*CO-Aux* are converted to R*CO-N(OMe)Me and then to R*CHO, but no examples are found of competition between the two first groups for nucleophiles.
    • The direct reduction of Weinreb amides to aldehydes is a standard. Since the pioneering work of Nahm and Weinreb (Nahm, S.; Weinreb, S. M. Tetrahedron Lett. 1981, 22, 3815), ca. 200 out of 500 papers have utilized DIBALH as the reducing agent, according to a SciFinder-based search, (b) Very often R*CO-Aux* are converted to R*CO-N(OMe)Me and then to R*CHO, but no examples are found of competition between the two first groups for nucleophiles.
  • 23
    • 0034622890 scopus 로고    scopus 로고
    • 2 at -78°C, attacks both the endo and exo CO groups of acylated oxazolidinones, whereas only the exocyclic CO reacts in the case of their 5,5-dimethyl analogues (Super Quats): (a) Bull, S. D.; Davies, S. G.; Nicholson, R. L.; Sanganee, H. J.; Smith, A. D. Tetrahedron: Asymmetry 2000, 11, 3475.
    • 2 at -78°C, attacks both the endo and exo CO groups of acylated oxazolidinones, whereas only the exocyclic CO reacts in the case of their 5,5-dimethyl analogues ("Super Quats"): (a) Bull, S. D.; Davies, S. G.; Nicholson, R. L.; Sanganee, H. J.; Smith, A. D. Tetrahedron: Asymmetry 2000, 11, 3475.
  • 24
    • 0041818295 scopus 로고    scopus 로고
    • To favor the selective attack on the hydroxamate, we have utilized ethereal solvents
    • (b) Bull, S. D.; Davies, S. G.; Nicholson, R. L.; Sanganese, H. J.; Smith, A. D. Org. Biomol. Chem. 2003, 1, 2886. To favor the selective attack on the hydroxamate, we have utilized ethereal solvents.
    • (2003) Org. Biomol. Chem , vol.1 , pp. 2886
    • Bull, S.D.1    Davies, S.G.2    Nicholson, R.L.3    Sanganese, H.J.4    Smith, A.D.5
  • 25
    • 0002884392 scopus 로고    scopus 로고
    • For the use of morpholine amides as an alternative to Weinreb amides, see: a
    • For the use of morpholine amides as an alternative to Weinreb amides, see: (a) Martín, R.; Romea, P.; Tey, C.; Urpí, F.; Vilarrasa, J. Synlett 1997, 1414.
    • (1997) Synlett , pp. 1414
    • Martín, R.1    Romea, P.2    Tey, C.3    Urpí, F.4    Vilarrasa, J.5
  • 37
    • 39349093292 scopus 로고    scopus 로고
    • In our experiments with the morpholine amide (4b, which is less reactive than the Weinreb amide 4a, we preferred stopping the reactions at conversions of 80-90, recovering the unreacted starting material, rather than adding larger amounts of DIBALH or increasing the reaction times, as byproducts coming from the attack on the other CO carbon atoms could appear
    • (a) In our experiments with the morpholine amide (4b), which is less reactive than the Weinreb amide (4a), we preferred stopping the reactions at conversions of 80-90%, recovering the unreacted starting material, rather than adding larger amounts of DIBALH or increasing the reaction times, as byproducts coming from the attack on the other CO carbon atoms could appear,
  • 38
    • 39349092703 scopus 로고    scopus 로고
    • 8O), that is 3 (R/OR = Me), was also cleaved successfully, in the same way. Independent studies regarding the reduction of morpholine amides to aldehydes will be reported in due course.
    • 8O), that is 3 (R/OR = Me), was also cleaved successfully, in the same way. Independent studies regarding the reduction of morpholine amides to aldehydes will be reported in due course.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.