Synlett 2009(2): 257-259  
DOI: 10.1055/s-0028-1087516
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Formation of Polysubstituted Tetrahydrofurans on an Iron Tricarbonyl η5-Pentadienyl Template

Steven D. R. Christie*a, Jaime Cumminsa, Mark R. J. Elsegooda, Graham Dawsonb
a Department of Chemistry, University of Loughborough, Loughborough, LE11 3TU, UK
Fax: +44(0)1509223925; e-Mail: s.d.christie@lboro.ac.uk;
b Prosidion, Watlington Road, Oxford, OX4 6LT, UK
Further Information

Publication History

Received 28 July 2008
Publication Date:
15 January 2009 (online)

Abstract

Formation of an iron tricarbonyl complexed η5-pentadienyl system through cleavage of a carbon-carbon sigma bond has provided entry to a series of highly substituted tetrahydrofurans via a 1,3-dipolar cycloaddition reaction.

    References and Notes

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  • 4a Christie SDR. Davoile R. Elsegood MRJ. Fryatt R. Jones RCF. Pritchard GJ. Chem. Commun.  2004,  2474 
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6

Typical Procedure - Preparation of Complex 4e
Iron tricarbonyl 2-buta-1,3-dienyl-cyclopropane-1,1-dicarboxylic acid dimethyl ester (0.100 g, 0.29 mmol) was added to a flame-dried round-bottom flask under an atmosphere of nitrogen and dissolved in dry CH2Cl2 (5 mL). p-Anisaldehyde (0.060 g, 0.60 mmol) and ZnBr2 (0.193 g, 0.86 mmol) were added and the reaction mixture stirred for 1.0 h at r.t. The resulting mixture was filtered through a pad of Celite and SiO2, then concentrated in vacuo, and the residue purified by silica flash chromatography eluting in PE-Et2O (4:1 v/v) to yield the two inseparable title complex diastereomers as a yellow-orange oil (0.101 g, 73%, dr = 4:1); HRMS-FAB: m/z calcd for C22H22O9Fe, [M+]: 486.0613; found: 486.0623. IR (neat film): νmax = 3006, 2954, 2841 (sp³ CH), 2048, 1979 (MCO), 1742, 1738, 1732 (C=O) cm. Assigned from combined spectrum: (i) ¹H NMR (400 MHz, CDCl3): δ (major diastereomer, cis) = 7.19-7.26 (2 H, m, ArH), 6.71-6.75 (2 H, m, ArH), 5.36-5.39 (1 H, m, CH2CHCH), 5.20-5.23 (1 H, m, CH2CHCH), 5.01-5.08 [1 H, m, CH(Ar)], 4.32-4.37 (1 H, m, CHCH2C), 3.71 (3 H, s, CO2CH3), 3.68 (3 H, s, OCH3), 3.09 (3 H, s, CO2CH3), 2.64-2.72 (1 H, m, CHCHHC), 2.37-2.44 (1 H, m, CHCHHC), 1.78-1.81 (1 H, m, CHHCHCH), 1.09 (1 H, t, J = 8.8 Hz, CH2CHCHCH), 0.51 (1 H, dd, J = 2.1, 9.6 Hz, CHHCHCH). ¹³C NMR (100 MHz, CDCl3): δ (major diastereomer, cis) = 171.2, 171.1 (CO2CH3), 159.4, 131.6 (ArC), 129.9, 113.2 (2 C, s, ArCH), 87.5 (CH2CHCH), 84.7 [CH(Ar)], 83.7 (CH2 CHCH), 78.4 (CHCH2C), 66.0 [C(CO2CH3)2], 59.4 (CH2CHCHCH), 55.2 (OCH3), 53.0, 52.3 (CO2 CH3), 41.1 (CH2CHCH), 40.4 (CHCH2C).(ii) ¹H NMR (400 MHz, CDCl3) δ (minor diastereomer, trans) = 7.19-7.26 (2 H, m, ArH), 6.71-6.75 (2 H, m, ArH), 5.36-5.39 (1 H, m, CH2CHCH), 5.12-5.23 (1 H, m, CH2CHCH), 5.01-5.08 [2 H, m, CHCH2C, CH(Ar)], 3.65-3.71 (6 H, m, OCH3, CO2CH3), 3.15 (3 H, s, CO2CH3), 2.92 (1 H, dd, J = 7.1, 13.1 Hz, CHCHHC), 2.10 (1 H, dd, J = 7.4, 13.1 Hz, CHCHHC), 1.78-1.81 (1 H, m, CHHCHCH), 0.91 (1 H, t,
J = 9.1 Hz, CH2CHCHCH), 0.38-0.40 (1 H, m, CHHCHCH). ¹³C NMR (100 MHz, CDCl3): δ (minor diastereomer, trans) = 170.3, 170.3 (CO2CH3), 159.4, 131.5 (ArC), 129.5, 113.2 (2 C, s, ArCH), 87.3 (CH2CHCH), 84.1 [CH(Ar)], 83.6 (CH2 CHCH), 79.0 (CHCH2C), 66.0 [C(CO2CH3)2], 62.0 (CH2CHCHCH), 55.2 (OCH3), 53.8, 52.3 (CO2 CH3), 40.9 (CH2CHCH), 40.7 (CHCH2C). MS:
m/z (%) = 486 (<1) [M+], 430 (28), 402 (66), 135 (100).

8

Crystal Data for 4a
C18H20FeO10, M = 452.19, a = 7.4917 (12), b = 10.4811 (16), c = 13.916 (2) Å, α = 72.126 (3), β= 78.035 (3), γ = 74.455 (2)˚, V = 992.6 (3) ų; colourless crystal, 0.76 × 0.04 × 0.02 mm³, D calc = 1.513 g cm, µ = 0.813 mm; 7243 data, 3482 unique (R int = 0.0381). Data were measured on a Bruker SMART 1000 diffractometer with MoKα radiation at 150 K. Data were corrected for absorption. The structure was solved by Patterson synthesis and refined on F ² values; H atom coordinates on atoms C(6), C(7), C(8), and C(9) were freely refined, other H atom parameters were constrained; R = 0.0432 [for 2567 observed data with F ² > 2σ(F ²)] and wR = 0.1046 (for all data). Deposition no. 696186. Crystal data have been deposited with the Cambridge Crystallographic Data Centre. Data can be retrieved in CIF format by quoting the relevant deposition number in an e-mail request to deposit@ccdc.cam.ac.uk.