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Synlett 2003(2): 0223-0226
DOI: 10.1055/s-2003-36793
LETTER
© Georg Thieme Verlag Stuttgart · New York

Vanadium(V)-Catalyzed Oxidation of (3R)-Linalool - The Selective Formation of Furanoid Linalool Oxides and their Conversion into Isocyclocapitelline Derivatives

Jens Hartung*, Simone Drees, Barbara Geiss, Philipp Schmidt
Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg
Fax: +49(931)8884606; e-Mail: hartung@chemie.uni-wuerzburg.de;
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Publikationsverlauf

Received 21 October 2002
Publikationsdatum:
22. Januar 2003 (online)

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Abstract

Oxidation of (3R)-linalool (2) with tert-butyl hydroperoxide (TBHP) occurs at the 6,7-position to selectively afford linalool oxide cis-1, if catalyzed by vanadium(V) Schiff base complexes 4. Substituted tetrahydrofuran cis-1 and its isomer trans-1 served as starting materials for short concise syntheses of β-carbolines cis-3 and trans-3 which are lower homologues of alkaloids (-)-isocyclocapitelline and (+)-cyclocapitelline.

Key words

tert-butyl hydroperoxide - linalool oxide - oxidation - Schiff base complex - vanadium

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Hartung, J.; Drees, S.; Greb, M.; Schmidt, P.; Svoboda, I.; Fuess, H.; Murso, A.; Stalke, D. Eur. J. Org. Chem., submitted.

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A solution of (3R)-linalool (2) (154 mg, 1.00 mmol) in CHCl3 (5 mL) and vanadium(V) complex 4b (36.3 mg, 0.10 mmol) was stirred for 5 min at 25 °C. Subsequently, TBHP (273 µL, 5.5 M in nonane, 1.50 mmol) was added and the deep red reaction mixture was stirred for additional 12 h at 25 °C. Afterwards, the solvent was removed at 250 mbar/40 °C to afford a dark brown residue which was filtered through a short pad of Al2O3 in order to remove the catalyst. The product was washed with Et2O (75 mL) from the column. Combined filtrate and eluate were concentrated in vacuo to provide an oil which was distilled under reduced pressure. The distillate was purified by column chromatography [SiO2, petroleum ether-Et2O-acetone, 5:2:1 (v/v/v); Rf cis-1 = 0.48; Rf trans-1 = 0.45] to provide 111 mg (65%) linalool oxide 1: colourless liquid, bp 80 °C/10 mbar (Kugelrohr, Lit. 78 °C/13 Torr), cis:trans = 61:39. cis-1: [α]D 25 +29.1 (c 1.1, CHCl3), ref. [17] : [α]D 25 +11.7 (c = 0.1, CH3OH). 1H NMR (250 MHz, CDCl3): δ = 1.11 (s, 3 H), 1.20 (s, 3 H), 1.29 (s, 3 H), 1.75-1.89 (m, 4 H), 2.05 (s br, 1 H, OH), 3.84 (dd, J = 8, 7 Hz, 1 H), 4.97 (dd, J = 11, 2 Hz, 1 H), 5.17 (dd, J = 17, 2 Hz, 1 H), 5.96 (dd, J = 17, 11 Hz, 1 H). trans-1: [α]D 25 -13.1 ( c 1.0, CHCl3), ref. [17] : [α]D 25 -10.1 (c 0.1, CH3OH). 1H NMR (250 MHz, CDCl3): δ = 1.10 (s, 3 H), 1.21 (s, 3 H), 1.29 (s, 3 H), 1.66-1.74 (mc, 1 H), 1.75-1.93 (m, 3 H), 2.05 (s, br., 1 H, OH), 3.78 (t, J = 7 Hz, 1 H), 4.98 (dd, J = 11, 2 Hz, 1 H), 5.18 (dd, J = 17, 2 Hz, 1 H), 5.85 (dd, J = 17, 11 Hz, 1 H).

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Control experiments [14] indicated that vanadium(V) complex 4b catalyzes oxidation of racemic mixtures of chiral bishomoallylic alcohols without kinetic resolution.

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cis-1-[5-(1-Hydroxy-1-methylethyl)-2-methyltetrahydro-furan-2-yl]-1,2,3,4-tetrahydro-9H-β-carboline: colorless crystals, mp 119 °C; [α]D 25 -22.9 (c 0.82, CHCl3). 1H NMR (250 MHz, CDCl3): δ = 1.08 (s, 3 H), 1.24 (s, 3 H), 1.38 (s, 3 H), 1.80-2.16 (m, 4 H), 2.78 (ddd, J = 12.1, 7.9, 5.5 Hz, 2 H), 3.21 (ddd, J = 12.5, 9.8, 5.5 Hz, 2 H), 4.02 (t, J = 7.0 Hz, 1 H), 4.06 (s, 1 H), 7.00-7.19 (m, 2 H), 7.24-7.36 (m, 1 H), 7.49 (mc, J = 7.0 Hz, 1 H), 8.75 (s, 1 H), 10.23 (s, 1 H). 13C NMR (63 MHz, CDCl3): δ = 20.5, 22.6, 25.0, 25.8, 27.4, 36.0, 43.9, 61.2, 71.2, 83.0, 85.6, 110.9, 112.8, 118.0, 119.0, 121.4, 135.4, 156.7, 175.5. MS (EI, 70 eV,): m/z (%) = 314 (3) [M+], 171 (100) [C11H11N2 +], 143 (6) [C8H15O2 +], 84 (11) [C5H8O+], 43 (10) [C3H6 +]. UV/Vis (EtOH): λmax (lg ε): 232 nm (3.76), 282 (3.81), 373 (2.46). C19H26N2O2 (314.4): Calcd C, 72.58; H, 8.33; N, 8.91. Found: C, 67.25; H, 8.26; N, 7.99. trans-1-[5-(1-Hydroxy-1-methylethyl)-2-methyltetrahydrofuran-2-yl]-1,2,3,4-tetrahydro-9H-β-carboline: colorless solid, mp 113 °C. [α]D 25 -19.5 (c 0.63, CHCl3). 1H NMR (250 MHz, CDCl3): δ = 1.08 (s, 3 H), 1.22 (s, 3 H), 1.40 (s, 3 H), 1.89-2.22 (m, 4 H), 2.68-2.90 (m, 2 H), 3.22 (ddd, J = 15.0, 9.8, 5.2 Hz, 2 H), 3.99 (dd, J = 8.2, 5.4 Hz, 1 H), 4.08-4.12 (m, 1 H), 7.05-7.20 (m, 2 H), 7.33 (mc, 1 H), 7.50 (mc, 1 H), 8.60 (s, 1 H). 13C NMR (63 MHz, CDCl3): δ = 21.6, 22.6, 24.6, 26.1, 28.8, 36.8, 43.0, 60.6, 70.4, 77.0, 86.6, 110.1, 110.9, 118.0, 119.0, 121.5, 142.3, 153.4, 174.1. MS (EI, 70 eV): m/z (%) = 314(3) [M+], 171(100) [C11H11N2 +], 143(6) [C8H15O2 +], 84(11) [C5H8O+], 43(10) [C3H6 +]. UV/Vis (EtOH): λmax (lg ε): 242 nm (4.52), 282 (3.85), 371 (2.57). C19H22N2O2 (314.4): Calcd C, 72.58; H, 8.33; N, 8.91. Found: C, 67.94; H, 8.06; N, 7.78.

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cis-1-[5-(1-Hydroxy-1-methylethyl)-2-methyltetrahydro-furan-2-yl]-9H-β-carboline cis-3: colorless solid, mp 161 °C. [α]D 25 -32.9 (c 0.57, CHCl3). 1H NMR (250 MHz, CDCl3): δ = 1.23 (s, 3 H), 1.45 (s, 3 H), 1.78 (s, 3 H), 1.75-3.08 (m, 4 H), 4.15 (t, J = 7.3 Hz, 1 H), 7.24 (ddd, J = 7.8, 6.1, 1.8 Hz, 1 H), 7.52 (mc, 2 H), 7.86 (d, J = 5.5 Hz, 1 H), 8.13 (d, J = 7.9 Hz, 1 H), 8.39 (d, J = 5.5 Hz, 1 H), 9.53 (s, 1 H). 13C NMR (63 MHz, CDCl3): δ = 24.2, 26.2, 27.6, 27.9, 37.3, 73.3, 88.4, 90.2, 111.5, 113.4, 119.7, 121.6, 121.7, 128.3, 133.2, 136.1, 138.0, 143.2, 148.0. MS (EI, 70 eV):
m/z (%) = 310(17) [M+], 151(24) [C16H15N2O+], 209 (100) [C14H12N2 +], 182 (11) [C10H16NO2 +], 43 (9) [C2H4O+]. UV/Vis (EtOH): λmax (lg ε): 242 nm (4.52), 288 (4.26), 348 (3.77). C19H22N2O2 (310.4): Calcd C, 73.52; H, 7.14; N, 9.03. Found: C, 72.86; H, 7.11; N, 8.68. trans-1-[5-(1-Hydroxy-1-methylethyl)-2-methyltetrahydrofuran-2-yl]-9H-β-carboline trans-3: colorless solid, mp 158 °C. [α]D 25
-50.5 (c 0.5, CHCl3). 1H NMR (250 MHz, CDCl3): δ = 1.25 (s, 3 H), 1.38 (s, 3 H), 1.72 (s, 3 H), 1.75-2.10 (m, 4 H), 4.15 (t, J = 7.6 Hz, 1 H), 7.22 (ddd, J = 7.9, 6.4, 1.5 Hz, 1 H), 7.48 (mc, 2 H), 7.86 (d, J = 5.2 Hz, 1 H), 8.11 (d, J = 7.5 Hz, 1 H), 8.36 (d, J = 5.2 Hz, 1 H), 10.48 (s, 1 H). 13C NMR (63 MHz, CDCl3): δ = 26.2, 26.7, 26.8, 28.4, 38.6, 72.6, 86.0, 88.2, 111.9, 114.1, 119.7, 121.5, 121.9, 128.4, 132.6, 133.0, 137.7, 142.9, 148.9. MS (EI, 70 eV): m/z (%) = 310 (17) [M+], 151 (24) [C16H15N2O+], 209 (100) [C14H12N2 +], 182 (11) [C10H16NO2 +], 43(9) [C2H4O+]. UV/Vis (EtOH): λmax (lg ε): 227 nm (4.09), 289 (4.03), 340 (3.57). C19H22N2O2 (310.4): Calcd C, 73.52; H, 7.14; N, 9.03. Found: C, 72.86; H, 7.11; N, 8.68.