A Synthesis of Demethyl Mycosporulone and its C-6 Epimer

Abstract

Demethyl mycosporulone was synthesized from the methyl ester of dihydro anisic acid in six steps. The key steps included an aldol/oxidation sequence and the formation of the exomethylene group by dehydration using Burgess salt.

spiro enol lactone - anticancer agent - mycosporulone

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11

Demethylmycosporulone: ¹H NMR (CDCl₃, 400 M Hz): epimer I (60%) δ 6.91-6.83 (m, 1 H), 6.35-6.31 (m, 1 H), 5.58 (d, J = 3.0 Hz, 1 H), 5.26 (d, J = 3.0 Hz, 1 H), 4.63 (s, 1 H), 3.92 (s, 1 H), 2.99 (m, 1 H), 2.73 (m, 1 H); epimer II (40%) δ 6.91-6.83 (m, 1 H), 6.35-6.31 (m, 1 H), 5.49 (d,
J = 3.0, 1 H), 5.22 (d, J = 3.0, 1 H), 4.70 (s, 1 H), 3.81 (s,
1 H), 3.12 (m, 1 H), 2.73 (m, 1 H): ¹³C NMR (CDCl₃,) epimer I δ 194.5, 193.0, 170.4, 150.5, 144.4, 127.2, 97.5, 73.3, 55.5, 29.9; epimer II δ 194.6, 193.6, 169.9, 150.1, 144.1, 127.4, 97.2, 73.4, 54.5, 30.2; IR: 3463.1, 2923.0, 1813.0, 1753.1, 1693.5, 1649.8, 1219.7; HRMS(EI): m/z Calcd for C₁₀H₈O₅ (M) 208.03717, obsd 208.03740.