메뉴 건너뛰기




Volumn 133, Issue 20, 2011, Pages 7916-7925

Hydrogen-bonding catalysis and inhibition by simple solvents in the stereoselective kinetic epoxide-opening spirocyclization of glycal epoxides to form spiroketals

Author keywords

[No Author keywords available]

Indexed keywords

ANOMERIC CARBON; COSOLVENTS; DIFFERENTIAL REACTION; ELECTROPHILES; EXPERIMENTAL DATA; FIRST-ORDER; HAMMETT ANALYSIS; HYDROGEN BONDINGS; INVERSION OF CONFIGURATION; METHYL GLYCOSIDES; NATURAL PRODUCTS; SECOND ORDERS; SIDE REACTIONS; SIDE-CHAINS; SPIROCYCLIZATION; SPIROKETALS; STEREO-SELECTIVE; STRUCTURAL MOTIFS; TRANSITION STATE;

EID: 79957767302     PISSN: 00027863     EISSN: 15205126     Source Type: Journal    
DOI: 10.1021/ja201249c     Document Type: Article
Times cited : (53)

References (89)
  • 70
    • 79957751987 scopus 로고    scopus 로고
    • 2/acetone solution of the glycal epoxide, which likely resulted in transient warming of the reaction mixture to a temperature at which the spirocyclization occurred. The reaction may also have proceeded during warming from -63 °C to rt prior to workup. Along these lines, low-temperature NMR analysis of the reaction during that warming process (-63 °C → rt over 15 min) herein indicated formation of a 80:0:20 ratio of 18: 19: 20
    • 2/acetone solution of the glycal epoxide, which likely resulted in transient warming of the reaction mixture to a temperature at which the spirocyclization occurred. The reaction may also have proceeded during warming from -63 °C to rt prior to workup. Along these lines, low-temperature NMR analysis of the reaction during that warming process (-63 °C → rt over 15 min) herein indicated formation of a 80:0:20 ratio of 18: 19: 20.
  • 74
    • 0000609662 scopus 로고
    • Absolute ρ values between 0 and 1 are usually seen as radical reactions, further narrowing our range of expected Hammett correlation values to approximately -1 to -5. (e.g.,;;;).
    • Absolute ρ values between 0 and 1 are usually seen as radical reactions, further narrowing our range of expected Hammett correlation values to approximately -1 to -5. (e.g., Pryor, W. A.; Lin, T. H.; Stanley, J. P.; Henderson, R. W. J. Am. Chem. Soc. 1973, 95, 6993-6998).
    • (1973) J. Am. Chem. Soc. , vol.95 , pp. 6993-6998
    • Pryor, W.A.1    Lin, T.H.2    Stanley, J.P.3    Henderson, R.W.4
  • 77
    • 79957709526 scopus 로고    scopus 로고
    • See Supporting Information for full details
    • See Supporting Information for full details.
  • 79
    • 79957785281 scopus 로고    scopus 로고
    • Attempts to distinguish between these possible transition states using computational methods have been unsuccessful thus far.
    • Attempts to distinguish between these possible transition states using computational methods have been unsuccessful thus far.
  • 81
    • 30144437908 scopus 로고
    • DMDO is prepared from acetone and was delivered herein as a 0.073 M solution in acetone
    • DMDO is prepared from acetone and was delivered herein as a 0.073 M solution in acetone: Murray, R. W.; Jeyaraman, R. J. Org. Chem. 1985, 50, 2847-2853
    • (1985) J. Org. Chem. , vol.50 , pp. 2847-2853
    • Murray, R.W.1    Jeyaraman, R.2
  • 82
    • 0030908605 scopus 로고    scopus 로고
    • Previous efforts in our laboratory to generate acetone-free DMDO using a published protocol have been unsuccessful
    • Previous efforts in our laboratory to generate acetone-free DMDO using a published protocol have been unsuccessful: Gilbert, M.; Ferrer, M.; Sanchez-Baeza, F.; Messeguer, A. Tetrahedron 1997, 53, 8643-8650
    • (1997) Tetrahedron , vol.53 , pp. 8643-8650
    • Gilbert, M.1    Ferrer, M.2    Sanchez-Baeza, F.3    Messeguer, A.4
  • 83
    • 79957689608 scopus 로고    scopus 로고
    • In addition, the epoxidation reaction itself produces one equivalent of acetone as a byproduct.
    • In addition, the epoxidation reaction itself produces one equivalent of acetone as a byproduct.
  • 85
    • 79957769448 scopus 로고    scopus 로고
    • 6 to achieve higher acetone concentrations in these experiments.
    • 6 to achieve higher acetone concentrations in these experiments.
  • 86
    • 0034702698 scopus 로고    scopus 로고
    • For lead references on MeOH-acetone liquid mixtures, see
    • For lead references on MeOH-acetone liquid mixtures, see: Venables, D. S.; Schmuttenmaer, C. A. J. Chem. Phys. 2000, 113, 3249-3260
    • (2000) J. Chem. Phys. , vol.113 , pp. 3249-3260
    • Venables, D.S.1    Schmuttenmaer, C.A.2
  • 88
    • 79957690206 scopus 로고    scopus 로고
    • Methyl glycosides 16a-e (cf. Table 2) were similarly observed exclusively with retention of configuration at the anomeric carbon. Interestingly, this stereoselectivity in the aryl substrate series is not seen in the aliphatic substrate series, where both glycoside anomers are observed (ref 5). This may result from the increased steric bulk of the C1-aryl substituent in 30, further disfavoring an axial orientation.
    • Methyl glycosides 16a-e (cf. Table 2) were similarly observed exclusively with retention of configuration at the anomeric carbon. Interestingly, this stereoselectivity in the aryl substrate series is not seen in the aliphatic substrate series, where both glycoside anomers are observed (ref 5). This may result from the increased steric bulk of the C1-aryl substituent in 30, further disfavoring an axial orientation.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.