Hydrochloric Acid → Helioxanthin

Participants

Reaction Steps

10-Benzo[1,3]dioxol-5-yl-furo[3′,4′:6,7]naphtho[1,2-d][1,3]dioxole-7,9-dione (1) was synthesized using procedure described in the literature (Charlton, J. L.; Oleschuk, C. J.; Chee, G. L. Hindered rotation in arylnaphthalene lignans. J. Org. Chem. 1996, 61, 3452-3457). The compound 1 (1.90 g, 5.25 mmol) in dry THF (100 mL) at 0° C. was added dropwise to a mixture of sodium borohydride (218 mg, 5.8 mmol) in dry THF (100 mL). The mixture was stirred at room temperature for 1 h and then acidified to pH 1-2 with 10% aqueous HCl solution. After stirring for 1 h, the mixture was extracted with ether (3×100 mL), concentrated in vacuo, and chromatographed using CHCl3 to give a lactone 2 (1.44 g, 79%) as a pale yellow powder. mp 242-244° C.; 1H NMR (DMSO-d6) δ 8.56 (s, 1H, H4), 7.93 (d, 1H, H5, J=8.4 Hz), 7.50 (d, 1H, H6, J=8.4 Hz), 7.01 (d, 1H, H2′, J=1.5 Hz), 6.95 (d, 1H, H5′, J=8.1 Hz), 6.87 (dd, 1H, H6′, J=1.5, 8.1 Hz), 6.08 (AB, 2H, 3′,4′-OCH2O—, Δδ=15.6 Hz, J=0.9 Hz), 5.99 (AB, 2H, 7,8-OCH2O—, Δδ=6.0 Hz, J=0.9 Hz), 5.28 (s, 2H, lactone-CH2—); MS (FAB, positive) m/z 349 [M+H]+.

Provenance & Evidence