Synlett 2002(11): 1883-1885
DOI: 10.1055/s-2002-34895
LETTER
© Georg Thieme Verlag Stuttgart · New York

One-Pot Michael Addition/Intramolecular Carbocyclization of Dimethyl Propargylmalonate with Nitroalkenes: A New Stereoselective [3+2] Annulation to 1-Nitro 2-Methylenecyclopentanes

Martial Guillaume, Estelle Dumez, Jean Rodriguez, Jean-Pierre Dulcère*
RéSo, Réactivité en Synthèse Organique, UMR 6516, Faculté des Sciences et Techniques de St Jérôme, Boîte D 12, Av. Esc. Normandie-Niemen, 13397, Marseille Cedex 20, France
e-Mail: jean-pierre.dulcere@univ.u-3mrs.fr;
Further Information

Publication History

Received 11 July 2002
Publication Date:
21 October 2002 (online)

Abstract

A new one-pot diastereoselective synthesis of nitro methylenecyclopentanes 3a-g has been achieved by [3+2] annulation of dimethyl propargylmalonate 2 and nitroalkenes 1a-g in the presence of Triton B.

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Typical Experiment: Triton B (40% in MeOH, 340 µL, 1 equiv) was added at 0 °C to a solution of (E)-2-nitro-but-2-ene 1a (1.3 equiv) and 2 (114 µL, 1.0 equiv) in anhyd THF (4 mL); the mixture was stirred at r.t. for 6 h. After addition of diethyl ether (2 mL), the pink coloured solution was filtered on a short pad of silica gel and the solvent was removed under reduced pressure. The crude oil was recrystallized in hexane to afford 3a: 56% yield; mp 72 °C; IR: ν = 2951, 1738, 1545, 1259 cm-1. 1Η ΝΜR (300 MHz, CDCl3): δ = 1.12 (d, J = 7.1, 3 H), 1.60 (s, 3 H), 3.00 (dt, J = 16.6, 3, 1 H), 3.17 (d, 16.6, 1 H), 3.71 (s, 3 H), 3.76 (s, 3 H), 3.79 (q, J = 7.3, 1 H), 5.26 (m, 2 H). 13C NMR (100 MHz, CDCl3): δ = 11.6, 21.3, 40.4, 48.6, 52.6, 53.1, 60.9, 96.3, 112.3, 148.3, 170.7, 170.8. MS (FAB+): m/z (%) = 272(5) [M + 1], 225(53), 165(100), 137(41). Crystal data: C12H17NO6, M = 271.269, orthorhombic, a = 6.9128(2), b = 12.1793(5), c = 16.5363(7) Å, V = 1392.20(10) Å3, T = 298 K, space group P212121, Z = 4, µ(Mo-Kα) = 0.10 mm-1, 9992 reflections measured, 1631 unique, R int = 0.032. The final wR(F 2) was 0.046.

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Assignments of stereochemistries for 3a-c were deduced from NOESY experiments.

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Crystal data for 3c were obtained from pure trans 3c (47%) isolated after recrystallization in hexane.

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Only one diastereomer could be detected by 1H NMR of the crude reaction mixture.

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Interplay between stereochemistry and ion pair formation in enolates of β-dicarbonyl compounds have been reported (ref. [24] ).

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Compound 3f was obtained in 75% yield when Triton B was added at -90 °C, the mixture kept at this temperature for 2 h, then r.t. 12 h.