Novel Spiro-Compound, Hyperolactone from Hypericum chinense L.

Abstract

A novel metabolite spiro-compound, hyperolactone was isolated from stems and leaves of Hypericum chinense L. The structure was deduced by 2D-NMR experiment, chemical transformation and finaly by X-ray crystallography.

Synthesis of hyperolactones A and C

“…Finally and much to our relief, deprotection of 20a was achieved using bromotrimethylsilane in dichloromethane at -20°to give the spirolactone 1 as a single product in 98% yield. The synthetic 1 was found to be identical with the natural product by comparing the mp, [α] D , ms, 1 H and 13 C NMR spectra with those reported [1]. The β-methoxymethyloxy isomer 20b was treated with bromotrimethylsilane to afford a 5R-isomer 1a as a single product in 95% yield.…”

“…The combined extracts were washed with water, dried and concentrated. The residue was chromatographed on silica gel (hexane/ethyl acetate, 10:1) to give 1 (5.9 mg, 98%) as a single product; mp 57°(recrystallized from ether and n-hexane); [lit [1] The α-methoxymethyloxy isomer 20a was treated with boiling tetrahydrofuran containing 3 M hydrochloric acid to give a mixture of 1 and its 2'-isomer 1b (88% yield), which was separated by HPLC [Shimadzu LC-3A; column: Cosmosil 5SI; n-hexanediethyl ether (95:5); 5 ml/minute]. The first peak (Rt 21.25 minutes) gave 1 and second peak (Rt 21.75 minutes) gave 1b as a colorless wax.…”

“…(-)-Hyperolactone A (1) was isolated from the leaves and stems of the Chinese plant Hypericum chinense L. by M. Tada and co-workers in 1989 [1]. Later, two structural relatives of 1, (+)-hyperolactone B (2) and (-)-hyperolactone C (3), were also isolated from the same plant as minor components in 1995 [2].…”

Xanthones from Stems of Hypericum chinense

“…Comparison of the 13 C-NMR chemical shifts of 2 and 1 showed good agreement on C-5-8, 9, 9a, and 10a. In its HMBC spectrum, the following correlations were observed: .…”

“…[11][12][13][14] In the course of our search for bioactive metabolites from plants, we became interested in the Hypericum plants and began to study their chemical constituents. As a part of this program, we studied the constituents of this plant, and isolated six new and four known xanthones.…”