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Synlett 2010(15): 2357-2360  
DOI: 10.1055/s-0030-1258040
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Asymmetric Organocatalytic Michael Addition of α,β-Unsaturated Ketone with 1,2,4-Triazole

Yufeng Zhou, Xin Li, Wenjun Li, Chunlin Wu, Xinmiao Liang*, Jinxing Ye*
Engineering Research Centre of Pharmaceutical Process Chemistry, Ministry of Education, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, P. R. of China
Fax: +86(21)64251830; e-Mail: yejx@ecust.edu.cn; e-Mail: liangxm@ecust.edu.cn;
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Received 13 April 2010
Publikationsdatum:
12. August 2010 (online)

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Abstract

The Michael addition of α,β-unsaturated ketone with triazole was efficiently catalyzed by the primary amine thiourea catalyst and the desired products were formed in high yields with moderate to excellent enantioselectivities.

Key words

asymmetric catalysis - 1,2,4-triazole - Michael addition - enone

    Primary data for this article are available online and can be cited using the following DOI: 10.4125/pd0003th:
  • Primary Data
    • FIDs and associated files for the ¹H and ¹³C NMR spectra for compounds 1-4 are summarized.
11

General Procedure for the Asymmetric Michael Addition of 1,2,4-Triazole to Cyclic Enones Catalyzed by 1
To a solution of cyclic enones (0.3 mmol) in toluene (2.0 mL) was added catalyst (19.2 mg, 0.04 mmol), 2-methoxy-benzoic acid (4.5 mg, 0.03 mmol), and 1,2,4-triazole (13.8 mg, 0.2 mmol). The reaction mixture was stirred at 15 ˚C for the time indicated in Table  [²] , and then the solvent was removed under vacuum. The residue was purified by silica gel chromatography to yield the desired addition product.

12

General Procedure for the Asymmetric Michael Addition of 1,2,4-Triazole to Open-Chain Enones Catalyzed by 1
To a solution of benzalacetone derivates (0.3 mmol) in CH2Cl2 (0.5 mL) was added catalyst (19.2 mg, 0.04 mmol), 4-nitrobenzoic acid (5.0 mg, 0.03 mmol), and 1,2,4-triazole (13.8 mg, 0.2 mmol). The reaction mixture was stirred at 15 ˚C for the time indicated in Table  [²] , and then the solvent was removed under vacuum. The residue was purified by silica gel chromatography to yield the desired addition product.

13

Crystal Structure Determination of Compound 9k
C12H12BrN3O, M = 294.16; a block crystal (0.410 × 0.337 × 0.251 mm), T = 293 (2), λ(MoKα) = 0.71073 Å, orthorhombic, space group: P212121, a = 7.9498 (12) Å, b = 12.4724 (17) Å, c = 25.479 (4) Å, V = 2526.3 (6) ų, 15229 total reflections, 5718 unique, Rint = 0.0851, R1 = 0.0437 (I > 2σ), wR2 = 0.0827, Flack parameter: 0.023 (11). Please see CCDC 782894.

14

Crystal Structure Determination of Compound 10
C12H19N3S2, M = 269.42; a block crystal (0.425 × 0.396 × 0.350 mm), T = 293 (2), λ(MoKα) = 0.71073 Å, monoclinic, space group: P21, a = 6.8332 (12) Å, b = 10.5576 (18) Å, c = 10.0377 (17) Å, V = 689.2 (2) ų, 3825 total reflections, 2766 unique, Rint = 0.0380, R1 = 0.0497 (I > 2σ), wR2 = 0.1301, Flack parameter: 0.06 (10). Please see CCDC 782895.