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Synlett 2004(9): 1613-1615  
DOI: 10.1055/s-2004-829064
LETTER
© Georg Thieme Verlag Stuttgart · New York

Convergent Formal Synthesis of (±)-Heliannuols A, K, and L from a Common Intermediate

Frédéric Lecornué, Jean Ollivier*
Laboratoire des Carbocycles (Associé au CNRS), Institut de Chimie Moléculaire et des Matériaux d"Orsay, Bât. 420, Université de Paris-Sud, 91405 ORSAY, France
Fax: +33(1)69156278; e-Mail: jollivie@icmo.u-psud.fr;
Further Information

Publication History

Received 31 March 2004
Publication Date:
01 July 2004 (online)

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Abstract

The intramolecular titanium-mediated cyclopropanation reaction of an oxa-ester bearing a terminal double bond followed by appropriate oxidation and dehydrohalogenation allows easy access to an aryl-fused oxacyclooctenone, an effective precursor of (±)-heliannuols A, K and L.

Key words

bicyclic compounds - cyclization - enones - heterocycles - organometallic reagents - radical reactions - titanium

8

8-Methoxy-2,2,6,9-tetramethyl-2 H -1-benzoxocin-3 (4 H )-one ( 6). Mp: 66 °C.1H NMR (250 MHz, CDCl3): δ = 6.88 (s, 1 H), 6.64 (s, 1 H), 5.75 (t, J = 7.5 Hz, 1 H), 3.83 (s, 3 H), 2.98 (d, J = 7.5 Hz, 2 H), 2.21 (s, 3 H), 2.06 (s, 3 H), 1.47 (s, 6 H). 13C NMR (63 MHz, CDCl3): δ = 208.65, 154.52, 145.04, 137.10, 132.82, 127.48, 126.38, 119.31, 108.46, 81.63, 55.50, 40.95, 24.59, 23.77, 16.13. IR (neat): 2984, 2938, 1713, 1504, 1464, 1395, 1205, 1152, 1022 cm-1. MS (EI): m/z (%) = 260 (72.4)[M+], 217 (15.2), 191 (35.5), 190 (49.1), 189 (100), 176 (34.3), 175 (43.8), 159 (8.6), 115 (8.3). HRMS: found 260.1414; C16H20O3 requires 260.1412.

9

We noted several omissions in the reported data of this compound. [3]
8-Methoxy-2,2,6,9-tetramethyl-5,6-dihydro-2 H -1-benzoxocin-3 (4 H )-one ( 7).
Mp: 71 °C. 1H NMR (250 MHz, CDCl3): δ = 6.74 (s, 1 H), 6.58 (s, 1 H), 3.80 (s, 3 H), 3.20-3.02 (m, 1 H), 2.61-2.39 (m, 2 H), 2.15 (s, 3 H), 2.07-1.90 (m, 1 H), 1.79-1.61 (m, 1 H), 1.49 (s, 3 H), 1.45 (s, 3 H), 1.34 (d, J = 7.1 Hz, 3 H). 13C NMR (90 MHz, CDCl3): δ = 212.98, 154.86, 145.96, 136.90, 127.46, 124.37, 108.71, 85.91, 55.45, 36.03, 34.65, 34.46, 24.36, 23.45, 20.43, 15.78. IR (neat): 3038, 2939, 2854, 1713, 1504, 1464, 1397, 1380, 1203, 1144, 1019 cm-1. MS (EI): m/z (%) = 262 (21.9) [M+], 178 (19.3), 165 (100), 163 (4.4), 91 (4.3). HRMS: found 262.1557; C16H22O3 requires 262.1568.

11

We noted omissions in the reported data of this compound. [3]
8-Methoxy-2,2,6,9-tetramethyl-3,4,5,6-tetrahydro-2 H -1-benzoxocin-3-ol ( 8). 1H NMR (250 MHz, CDCl3): δ = 6.76 (s, 1 H, cis), 6.72 (s, 1 H, trans), 6.62 (s, 1 H, cis), 6.58 (s, 1 H, trans), 3.81 (s, 6 H), 3.43 (d, J = 9.1 Hz, 2 H), 3.30-3.11 (m, 2 H), 2.16 (s, 6 H), 2.15-1.94 (m, 8 H), 1.62 (br s, 2 H), 1.44 (s, 6 H), 1.38 (s, 6 H), 1.29 (d, J = 7.1 Hz, 6 H). MS (EI, trans isomer): m/z (%) = 264 (26.4) [M+], 246 (8.7), 178 (16.0), 166 (21.6), 165 (100). MS (EI, cis isomer): m/z (%) = 264 (17.2) [M+], 246 (5.8), 178 (13.1), 166 (17.6), 165 (100). HRMS (trans isomer): found 264.1735; C16H24O3 requires 264.1725. HRMS (cis isomer): found 264.1716; C16H24O3 requires 264.1725.

13

8-Methoxy-4,4,7,9b-tetramethyl-1a,9b-dihydro-2 H -oxireno[ e ][1]benzoxocin-3 (4 H )-one ( 9). Mp: 89 °C. 1H NMR (250 MHz, CDCl3): δ = 6.86 (s, 1 H), 6.79 (s, 1 H), 3.85 (s, 3 H), 3.24 (dd, J = 9.6, 4.0 Hz, 1 H), 2.89 (dd, J = 12.4, 4.0 Hz, 1 H), 2.19 (s, 3 H), 2.18-2.11 (m, 1 H), 1.58 (s, 3 H), 1.56 (s, 3 H), 1.37 (s, 3 H). 13C NMR (50 MHz, CDCl3): δ = 207.96, 155.26, 144.27, 131.50, 126.82, 126.53, 109.82, 87.09, 61.25, 59.14, 55.60, 42.50, 25.64, 24.17, 23.62, 16.21. IR (neat): 2984, 2936, 1714, 1505, 1464, 1398, 1378, 1205, 1148, 1020 cm-1. MS (EI):
m/z (%) = 276 (94.5) [M+], 247 (25.0), 219 (77.1), 205 (78.0), 192 (28.7), 189 (100), 178 (15.9), 177 (16.7), 176 (28.0), 175 (50.3), 165 (87.6), 164 (39.9), 163 (39.9), 162 (41.9), 149 (32.4), 91 (26.6), 69 (22.9). HRMS: found 276.1352; C16H22O3 requires 276.1361.