Synthesis of Hemitectol, Tectol, and Tecomaquinone I

Melissa M. Cadelis; David Barker; Brent R. Copp

doi:10.1055/s-0032-1317541

Synlett, Table of Contents

Synlett 2012; 23(20): 2939-2942
DOI: 10.1055/s-0032-1317541

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Synthesis of Hemitectol, Tectol, and Tecomaquinone I

Melissa M. Cadelis

School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand Fax: +64(9)3737422 Email: b.copp@auckland.ac.nz

,

David Barker

School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand Fax: +64(9)3737422 Email: b.copp@auckland.ac.nz

,

Brent R. Copp*

School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand Fax: +64(9)3737422 Email: b.copp@auckland.ac.nz

› Author Affiliations

Abstract

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Abstract

The first total syntheses of Tectona grandis (teak) natural products hemitectol and tectol are described. The observation of spontaneous dimerisation of hemitectol to tectol suggests the monomer is the true natural product and that the dimer is an artifact of isolation.

Key words

cyclisation - dimerisation - quinone - ring closure - total synthesis

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References

References and Notes
1 Chan ST. S, Pearce AN, Januario AH, Page MJ, Kaiser M, McLaughlin RJ, Harper JL, Webb VL, Barker D, Copp BR. J. Org. Chem. 2011; 76: 9151
2 Sumthong P, Romero-González RR, Verpoorte R. J. Wood. Chem. Tech. 2008; 28: 247
3 Sandermann W, Simatupang MH. Chem. Ber. 1964; 97: 588
4 Lemos TL. G, Monte FJ. Q, Santos AK. L, Fonseca AM, Santos HS, Oliveira MF, Costa SM. O, Pessoa OD. L, Braz-Filho R. Nat. Prod. Res. 2007; 21: 529
5 tert-Butyl(4-methoxynaphthalen-1-yloxy)dimethylsilane (8) IR (ATR): 2929, 2857, 1625, 1596, 1461, 1384, 1273, 1095 cm^–1. ¹H NMR (400 MHz, CDCl₃): δ = 8.25–8.23 (m, 2 H, H-5, H-8), 7.60–7.56 (m, 2 H, H-6, H-7), 6.86 (d, J = 8.5 Hz, 1 H, H-3), 6.73 (d, J = 8.5 Hz, 1 H, H-2), 4.03 (s, 3 H, OCH₃), 1.20 (s, 9 H, H-4′, H-5′, H-6′), 0.36 (s, 6 H, H-1′, H-2′). ¹³C NMR (100 MHz, CDCl₃): δ = 149.9 (C-1), 145.2 (C-4), 128.6 (ArC), 126.6 (ArC), 125.8 (ArCH), 125.5 (ArCH), 122.5 (ArCH), 122.0 (ArCH), 111.9 (C-3), 103.5 (C-2), 55.7 (OCH₃), 26.0 (C-4′, C-5′, C-6′), 18.5 (C-3′), –4.2 (C-1′, C-2′). ESI-HRMS: m/z calcd for C₁₇H₂₅O₂Si [MH⁺]: 289.1618; found: 289.1624.
6 4-(tert-Butyldimethylsiloxy)naphthalene-1-ol (9) IR (ATR): 3255, 2929, 1595, 1471, 1347, 1266, 1069 cm^–1. ¹H NMR (400 MHz, CDCl₃): δ = 8.10–8.09 (m, 2 H, H-5, H-8), 7.50–7.47 (m, 2 H, H-6, H-7), 6.68 (s, 2 H, H-2, H-3), 1.09 (s, 9 H, H-4′, H-5′, H-6′), 0.24 (s, 6 H, H-1′, H-2′). ¹³C NMR (100 MHz, CDCl₃): δ = 145.4 (C-1), 138.7 (C-4), 126.4 (2 × Ar-C), 125.7 (ArCH), 125.5 (ArCH), 122.7 (ArCH), 121.5 (ArCH), 112.0 (C-2), 108.3 (C-3), 25.9 (C-4′, C-5′, C-6′), 18.4 (C-3′), –4.3 (C-1′, C-2′). ESI-HRMS: m/z calcd for C₁₆H₂₃O₂Si [MH⁺]: 275.1462; found: 275.1462.
7 Lee YR, Kim YM. Helv. Chim. Acta 2007; 90: 2401
8 tert-Butyl(2,2-dimethyl-2H-benzo[h]chromen-6-yloxy)dimethylsilane (10) IR (ATR): 2930, 1595, 1457, 1409, 1370, 1274, 1084 cm^–1. ¹H NMR (400 MHz, CDCl₃): δ = 8.15–8.03 (m, 2 H, H-7, H-10), 7.43–7.40 (m, 2 H, H-8, H-9), 6.54 (s, 1 H, H-5), 6.35 (d, J = 9.7 Hz, 1 H, H-4), 5.63 (d, J = 9.7 Hz, 1 H, H-3), 1.49 (s, 6 H, H-11, H-12), 1.08 (s, 9 H, H-4′, H-5′, H-6′), 0.24 (s, 6 H, H-1′, H-2′). ¹³C NMR (100 MHz, CDCl₃): δ = 144.8 (C-6), 142.4 (C-10b), 129.9 (C-3), 128.3 (ArC), 126.0 (ArC), 125.5 (ArCH), 125.3 (ArCH), 122.9 (C-4), 122.5 (ArCH), 121.8 (ArCH), 115.0 (C-4a), 110.9 (C-5), 76.2 (C-2), 27.6 (C-11, C-12), 25.9 (C-4′, C-5′, C-6′), 18.4 (C-3′), –4.2 (C-1′, C-2′). ESI-HRMS: m/z calcd for C₂₁H₂₉O₂Si [MH⁺]: 341.1931; found: 341.1919.
9 Hemitectol (6) Dark yellow oil. IR (ATR): 3419, 2973, 1586, 1451, 1402, 1369, 1360, 1257, 1070 cm^–1. ¹H NMR (400 MHz, DMSO-d ₆): δ = 8.03–7.96 (m, 2 H, H-7, H-10), 7.46–7.37 (m, 2 H, H-8, H-9), 6.60 (s, 1 H, H-5), 6.43 (d, J = 9.5 Hz, 1 H, H-4), 5.75 (d, J = 9.5 Hz, 1 H, H-3), 1.42 (s, 6 H, H-11, H-12). ¹³C NMR (100 MHz, DMSO-d ₆): δ = 146.4 (C-6), 143.7 (C-10b), 130.4 (C-3), 125.6 (ArCH), 125.1 (ArC), 124.9 (ArC), 124.7 (ArCH), 122.6 (C-4), 122.1 (ArCH), 121.1 (ArCH), 115.2 (C-4a), 105.9 (C-5), 75.7 (C-2), 27.1 (C-11, C-12). ESI-HRMS: m/z calcd for C₁₅H₁₅O₂ [MH⁺]: 227.1067; found: 227.1063.
10 Tectol (5) White solid; 206–209 °C (lit.² 207–208 °C). IR (ATR): 3420, 2973, 1586, 1451, 1402, 1369, 1361, 1221, 1071 cm^–1. ¹H NMR (400 MHz, DMSO-d ₆): δ = 8.17–8.08 (m, 4 H, H-7, H-7′, H-10, H-10′), 7.52–7.44 (m, 4 H, H-8, H-8′, H-9, H-9′), 5.78 (d, J = 9.9 Hz, 2 H, H-4, H-4′), 5.59 (d, J = 9.9 Hz, 2 H, H-3, H-3′), 1.45 (s, 6 H, H-11, H-11′), 1.43 (s, 6 H, H-12, H-12′). ¹³C NMR (100 MHz, DMSO-d ₆): δ = 144.1 (C-6, C-6′), 140.6 (C-10b, C-10b′), 130.0 (C-3, C-3′), 125.5 (2 × ArC), 125.4 (2 × ArCH), 125.1 (2 × ArC), 125.0 (2 × ArCH), 122.5 (2 × ArCH), 121.2 (2 × ArCH), 120.9 (C-4, C-4′), 115.9 (C-4a, C-4a′), 113.2 (C-5, C-5′), 75.2 (C-2, C-2′), 27.0 (C-11, C-11′, C-12, C-12′). ESI-HRMS: m/z calcd for C₃₀H₂₆O₄Na [MNa⁺]: 473.1723; found: 473.1714.
11 Bandaranayake WM, Crombie L, Whiting DA. J. Chem. Soc. 1971; 811
12 Tecomaquinone I (4) Green solid; mp 187–189 °C (lit.² 188–189 °C). IR (ATR): 3360, 2978, 1690, 1568, 1277, 1237, 1197, 1109 cm^–1. ¹H NMR (400 MHz, DMSO-d ₆): δ = 8.14–8.09 (m, 2 H, H-7, H-10), 8.07–8.05 (m, 1 H, H-2′), 8.04–8.01 (m, 1 H, H-5′), 7.95–7.86 (m, 2 H, H-3′, H-4′), 7.65–7.60 (m, 1 H, H-9), 7.57–7.53 (td, J = 7.0, 1.5 Hz, 1 H, H-8), 6.36 (d, J = 9.9 Hz, 1 H, H-4), 6.34 (d, J = 9.1 Hz, 1 H, H-7′), 5.62 (d, J = 9.9 Hz, 1 H, H-3), 5.44 (td, J = 9.0, 1.5 Hz, 1 H, H-8′), 2.03 (br s, 3 H, H-11′), 1.60 (s, 3 H, H-12), 1.59 (s, 3 H, H-10′), 1.55 (s, 3 H, H-11). ¹³C NMR (100 MHz, DMSO-d ₆): δ = 182.8 (C-6′), 181.6 (C-1′), 146.5 (C-6), 142.4 (C-10b), 141.7 (C-9′), 135.9 (ArC), 135.4 (ArC), 134.0 (ArC), 133.8 (2 × ArCH), 132.9 (ArC), 131.3 (ArC), 128.2 (ArCH), 126.7 (ArCH), 126.5 (ArCH), 125.3 (ArCH), 125.3 (C-3), 124.7 (ArC), 123.8 (C-4), 122.5 (ArCH), 121.8 (ArCH), 117.6 (C-8′), 113.0 (C-4a), 111.2 (C-5), 75.5 (C-2), 67.3 (C-7′), 28.2 (C-12), 25.5 (C-10′), 25.2 (C-11), 18.7 (C-11′). ESI-HRMS: m/z calcd for C₃₀H₂₅O₄ [MH⁺]: 449.1747; found: 449.1726.
13 Gonzalez AG, Barroso JT, Cardona RJ, Medina JM, Luis FR. An. Quim. 1977; 73: 538
14 Tohma H, Morioka H, Takizawa S, Arisawa M, Kita Y. Tetrahedron 2001; 57: 345
15 Furan Dimer A (13) Brown solid; mp 112.1–115.1 °C. IR (ATR): 2938, 1637, 1598, 1457, 1382, 1100 cm^–1. ¹H NMR (400 MHz, CDCl₃): δ = 8.18–8.17 (m, 4 H, H-8, H-8′, H-9, H-9′), 7.52–7.46 (m, 4 H, H-7, H-10, H-7′, H-10′), 6.77 (s, 2 H, H-5, H-5′), 4.94 (d, J = 6.5 Hz, 2 H, H-4, H-4′), 3.97 (s, 6 H, OCH₃, OCH₃′), 2.63 (d, J = 6.5 Hz, 2 H, H-3, H-3′), 1.57 (s, 6 H, H-11, H-11′), 1.46 (s, 6 H, H-12, H-12′). ¹³C NMR (100 MHz, CDCl₃): δ = 149.7 (C-6, C-6′), 142.8 (C-10b, C-10b′), 126.3 (2 × ArC), 126.3 (2 × ArC), 126.0 (2 × ArCH), 126.0 (2 × ArCH), 122.0 (2 × ArCH), 121.8 (2 × ArCH), 115.4 (C-4a, C-4a′), 77.3 (C-2, C-2′), 73.1 (C-4, C-4′), 55.8 (OCH₃, OCH₃′), 49.4 (C-3, C-3′), 27.9 (C-12, C-12′), 26.9 (C-11, C-11′). ESI-HRMS: m/z calcd for C₃₂H₃₃O₅ [MH⁺]: 497.2323; found: 497.2307.
16 Furan Dimer B (14) Brown solid; mp 216.0–218.6 °C. IR (ATR): 2938, 1637, 1598, 1457, 1382, 1100 cm^–1. ¹H NMR (400 MHz, CDCl₃): δ = 8.23–8.15 (m, 4 H, H-7, H-7′, H-10, H-10′), 7.52–7.42 (m, 4 H, H-8, H-8′, H-9, H-9′), 7.06 (s, 1 H, H-5), 6.96 (s, 1 H, H-5′), 5.13 (d, J = 8.3 Hz, 1 H, H-4), 4.88 (d, J = 10.5 Hz, 1 H, H-4′), 4.07 (s, 3 H, OCH₃), 4.01 (s, 3 H, OCH₃′), 2.74 (t, J = 8.3 Hz, 1 H, H-3), 2.10 (dd, J = 10.5, 8.3 Hz, 1 H, H-3′), 1.70 (s, 3 H, H-12′), 1.64 (s, 3 H, H-11), 1.60 (s, 3 H, H-11′), 1.17 (s, 3 H, H-12). ¹³C NMR (100 MHz, CDCl₃): δ = 150.0 (C-6′), 149.1 (C-6), 141.5 (C-10b), 141.0 (C-10b′), 126.6 (2 × ArCH), 126.1 (2 × ArCH), 125.9 (ArC), 125.9 (ArC), 125.5 (ArC), 125.1 (ArC), 122.0 (ArCH), 121.9 (2 × ArCH), 121.6 (ArCH), 119.8 (C-4a′), 116.6 (C-4a), 102.8 (C-5), 99.4 (C-5′), 80.6 (C-2′), 77.8 (C-4), 76.6 (C-2′), 76.2 (C-4′), 56.0 (OCH₃), 55.8 (OCH₃′), 55.6 (C-3′), 49.6 (C-3), 31.7 (C-12′), 29.9 (C-11), 24.0 (C-11′), 22.6 (C-12). ESI-HRMS: m/z calcd for C₃₂H₃₃O₅ [MH⁺]: 497.2323; found: 497.2305.
17 Fraga BM, Garcia VP, Gonzalez AG, Hernandez MG, Hanson JR, Hitchcock PB. J. Chem. Soc. 1983; 2687