Synlett 2016; 27(01): 17-20
DOI: 10.1055/s-0035-1560504
letter
© Georg Thieme Verlag Stuttgart · New York

Asymmetric Organocatalytic Synthesis of Cyclopentane γ-Nitroketones

Widad Al-Ani
School of Chemistry, Food and Pharmacy, University of Reading, Whiteknights, Reading, Berks RG6 6AD, UK   Email: [email protected]
,
Kenneth Shankland
School of Chemistry, Food and Pharmacy, University of Reading, Whiteknights, Reading, Berks RG6 6AD, UK   Email: [email protected]
,
Alexander J. A. Cobb*
School of Chemistry, Food and Pharmacy, University of Reading, Whiteknights, Reading, Berks RG6 6AD, UK   Email: [email protected]
› Author Affiliations
Further Information

Publication History

Received: 14 September 2015

Accepted: 25 September 2015

Publication Date:
15 October 2015 (online)


Dedicated to Professor Steven V. Ley CBE FRS on the occasion of his 70th birthday

Abstract

This paper describes the use of bifunctional thiourea catalysts in the intramolecular reaction of a nitronate with conjugated ketones to generate the corresponding γ-nitroketones. In contrast to our previous studies in this area, we obtained the cis-functionalized systems as the major diastereoisomers in good yields and reasonable selectivities.

 
  • References and Notes

  • 1 For general reviews, see: Cobb AJ. A. In Enantioselective Organocatalyzed Reactions II: Asymmetric C–C Bond Formation Processes. Mahrwald R. Springer; Dordrecht: 2011. and other chapters within both volumes I and II
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  • 3 Nodes WJ, Shankland K, Rajkumar S, Cobb AJ. A. Synlett 2010; 3011
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  • 8 Representative Procedure To a solution of (E)-8-nitro-1-phenyloct-3-en-2-one (1, 150 mg, 0.6 mmol) in MeCN (5 mL) was added catalyst I (60.1 mg, 20 mol%) in one portion. The resulting mixture was stirred at r.t. for 7 d, whereupon the solvent was removed under reduced pressure, and the residue was purified by column chromatography (Et2O–hexane, 1:3) to afford cis-1-(2-nitrocyclopentyl)-3-phenylpropan-2-one (2d) as a colorless oil (140 mg, 94%).
  • 9 Analytical Data for Compound 2d The ee was determined by chiral HPLC analysis at 20 °C to be 65% {Chiralpak AD-H [0.46 cm × 25 cm]: t R1 = 32.7 min, t R2 = 39.2 min}. 1H NMR (400 MHz, CDCl3): δ = 1.45–1.48 (2 H, m, CH2CH2CHNO2), 1.65–1.68 (2 H, m, CH2CHRCHNO2), 2.10 (1 H, m, CHHCHNO2), 2.34 (1 H, m, CHHCHNO2), 2.48 [2 H, m, cpCH2C(O)], 2.70 (1 H, m, CHNO2CHR), 3.80 (2 H, s, CH2Ph), 5.04 (1 H, dt, J = 6.6, 2.2 Hz, CHNO2), 7.17–7.30 (5 H, m, ArH). IR: 1260, 2973, 1714, 1544, 1458 cm–1. HRMS: m/z calcd for C14H18O3N [MH+]: 248.1132; found: 248.1133.
  • 10 CCDC 1406015 contains the supplementary crystallographic data for this paper. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/getstructures.