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Volumn 125, Issue 51, 2003, Pages 15902-15911

Isotope Effects and the Nature of Selectivity in Rhodium-Catalyzed Cyclopropanations

Author keywords

[No Author keywords available]

Indexed keywords

ACTIVATION ENERGY; CARBON; CATALYST SELECTIVITY; COMPLEXATION; ISOTOPES; REACTION KINETICS; RHODIUM; STEREOCHEMISTRY;

EID: 0346364994     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja036025q     Document Type: Article
Times cited : (138)

References (53)
  • 4
    • 0000139463 scopus 로고
    • The only effective catalysts for highly enantioselective and diasteoselective cyclopropanations with ethyl diazoacetate have been ruthenium-based catalysts. For examples, see: (a) Nishiyama, H.; Itoh, Y.; Matsumoto, H.; Park, S.-B.; Itoh, K. J. Am. Chem. Soc. 1994, 116, 2223-2224.
    • (1994) J. Am. Chem. Soc. , vol.116 , pp. 2223-2224
    • Nishiyama, H.1    Itoh, Y.2    Matsumoto, H.3    Park, S.-B.4    Itoh, K.5
  • 25
  • 27
    • 0348168116 scopus 로고    scopus 로고
    • note
    • 4, would have increased concerns over the identity of the actual catalyst.
  • 32
    • 0001363007 scopus 로고    scopus 로고
    • For a discussion of theoretical methods applied to transition-metal containing systems, see: Siegbahn, P. E. M.; Blomberg, M. R. A. Chem. Rev. 2000, 100, 421-437.
    • (2000) Chem. Rev. , vol.100 , pp. 421-437
    • Siegbahn, P.E.M.1    Blomberg, M.R.A.2
  • 39
    • 0347538373 scopus 로고    scopus 로고
    • note
    • The potential energy barrier is 2.6 kcal/mol (including zpe) versus a weak π complex with a carbene-styrene separation of 3.5 Å. The π complex is kinetically irrelevant because it would not be a bound species on the free energy surface at 25°C, but its energy is relevant in showing the shape of the potential energy surface.
  • 41
    • 0024841752 scopus 로고
    • The calculations used the program QUIVER (Saunders, M.; Laidig, K. E.; Wolfsberg, M. J. Am. Chem. Soc. 1989, 111, 8989-8994) with Becke3LYP frequencies scaled by 0.9614. (Scott, A. P.; Radom, L. J. Phys. Chem. 1996, 100, 16502-16513).
    • (1989) J. Am. Chem. Soc. , vol.111 , pp. 8989-8994
    • Saunders, M.1    Laidig, K.E.2    Wolfsberg, M.3
  • 42
    • 0011083273 scopus 로고    scopus 로고
    • The calculations used the program QUIVER (Saunders, M.; Laidig, K. E.; Wolfsberg, M. J. Am. Chem. Soc. 1989, 111, 8989-8994) with Becke3LYP frequencies scaled by 0.9614. (Scott, A. P.; Radom, L. J. Phys. Chem. 1996, 100, 16502-16513).
    • (1996) J. Phys. Chem. , vol.100 , pp. 16502-16513
    • Scott, A.P.1    Radom, L.2
  • 47
    • 0348168115 scopus 로고    scopus 로고
    • note
    • 13C KIE arises from a temperature-independent ratio of imaginary frequencies for the isotopomers. Because of this, there is very little variation in the predicted KIEs with temperature.
  • 49
    • 0346907535 scopus 로고    scopus 로고
    • note
    • In the particular case of 11, taking steps of 0.05 Å along the minimum-energy path in both directions afforded geometries with a lower predicted free energy (including entropy and enthalpic and zpe corrections calculated from unscaled frequencies at 298 K). Thus, despite the low potential energy barrier, other effects appear to have relatively little impact on the position of the transition state.
  • 50
    • 0347538372 scopus 로고    scopus 로고
    • note
    • 4 affords mainly the trimer (see ref 3) but gives cyclopropanation adducts in an approximately 12:1 ratio.
  • 51
    • 0347538371 scopus 로고    scopus 로고
    • note
    • These studies used default parameters in CS Chem3D Pro, Version 5.0 (1999), CambridgeSoft Corp.: Cambridge, MA, treating the carboxylate carbons as alkenyl carbons. Several of the parameters employed were unrealistic-for example the Rh-O bond distance was only ≈ 1.93 Å-but were likely satisfactory for the purpose of identifying accessible conformations.
  • 53
    • 0348168113 scopus 로고    scopus 로고
    • note
    • An 8% error from NMR in the ratio of the product to the starting material would correspond to a change from 84:16 (5.25:1) to 85:15 (5.67:1) (5.67/5.25 = 1.08).


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.