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Synlett
Volumn , Issue 4, 2009, Pages 667-670
Guanidine-urea bifunctional organocatalyst for asymmetric epoxidation of 1,3-diarylenones with hydrogen peroxide
Author keywords

Electron deficient olefin; Epoxidation; Guanidine; Hydrogen peroxide; Urea
Indexed keywords

EID: 62349125985     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-0028-1087811     Document Type: Article
Times cited : (56)
References (61)
  • 2
    • 0003445429 scopus 로고    scopus 로고
    • Jacobsen, E. N, Pfaltz, A, Yamamoto, H, Eds, Springer: New York
    • (b) Comprehensive Asymmetric Catalysis; Jacobsen, E. N.; Pfaltz, A.; Yamamoto, H., Eds.; Springer: New York, 1999.
    • (1999) Comprehensive Asymmetric Catalysis
  • 3
    • 0003544583 scopus 로고    scopus 로고
    • 2nd ed, Ojima, I, Ed, Wiley: New York
    • (c) Catalytic Asymmetric Synthesis, 2nd ed.; Ojima, I., Ed.; Wiley: New York, 2000.
    • (2000) Catalytic Asymmetric Synthesis
  • 49
    • 62349126211 scopus 로고    scopus 로고
    • Synthesis of Catalyst 1a and Spectral Data for 1a-e To a solution of guanidine (S,S)-1f10a (258 mg, 0.317 mmol) in CH2Cl2 (3.0 mL) was added TFA (3.0 mL) at 0°C. The reaction mixture was warmed to r.t. and stirred for 2 h. The resulting mixture was concentrated in vacuo to give diamine. To a solution of the diamine in THF (6.0 mL) was added phenyl isocyanate (0.21 mL, 1.90 mmol, and the mixture was stirred for 12 h. The resulting mixture was concentrated in vacuo, and the residue was purified by flash column chromatography on silica gel (n-hexane-EtOAc, 4:1 to 1:1, CHCl3-MeOH, 9:1) to give 1a as a TFA salt (Scheme 1, The counteranion of 1a was exchanged into Cl- by treatment with sat. aq NH4Cl and EtOAc solution, and gave 1a as a HCl form in 81% yield from 1f (219 mg, 0.257 mmol, Compound 1a: [α]D24 -41.2 c 1.3, CH
    • +]: 936.4773; found: 936.4734.
  • 52
    • 62349092627 scopus 로고    scopus 로고
    • We recycled the catalyst 1b five times under the conditions of entry 11 in Table 1. In these reactions, the yields and enantioselectivities were as follows: 2nd run: 95% with 90% ee; 3rd run: 99% with 90% ee; 4th run: 99% with 91% ee; and 5th run: 99% with 89% ee.
    • We recycled the catalyst 1b five times under the conditions of entry 11 in Table 1. In these reactions, the yields and enantioselectivities were as follows: 2nd run: 95% with 90% ee; 3rd run: 99% with 90% ee; 4th run: 99% with 91% ee; and 5th run: 99% with 89% ee.
  • 58
    • 62349109877 scopus 로고    scopus 로고
    • Typical Procedure for Asymmetric Epoxidation of 4a A mixture of enone 4a (20.8 mg, 0.10 mmol) and guanidine-urea organocatalyst (S,S)-1b (5.6 mg, 0.005 mmol, 5 mol, in toluene (0.95 mL) was cooled at -10°C. To the mixture was added 1 M aq NaOH (0.050 mL, 0.050 mmol) and 30% aq H2O2 (0.051 mL, 0.50 mmol of H 2O2, The mixture was stirred vigorously at -10°C under argon atmosphere for 6 h. To the reaction mixture was added sat. aq NH4Cl, and the organic layer was extracted with EtOAc. The combined organic extracts were dried over MgSO4, filtered, and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel (n-hexane-EtOAc, 100:1 to 10:1) to give epoxy ketone 5a (22.3 mg, 99, and catalyst 1b was quantitatively recovered 5.6 mg, >99, The ee and absolute configuration of the epoxy ketone 5a was determined by HPLC using
    • 17a
  • 59
    • 62349089805 scopus 로고    scopus 로고
    • In the case of aliphatic substituted enones, enantioselectivities were moderate to low ex. R1, Me, R2, Ph, 99% yield with 41% ee
    • 2 = Ph, 99% yield with 41% ee).
  • 60
    • 62349126489 scopus 로고    scopus 로고
    • 6.
    • 6.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.