Yu-Shia Cheng

Uncommon diterpenes with the skeleton of six-five-six fused-rings from Taiwania cryptomerioides

Abstract Four diterpenoid aldehydes and one norditerpenoid ketone having the uncommon skeleton of six-five-six fused-rings were isolated from the leaves of Taiwania crytomerioides .

Diterpenes and related cycloadducts from Taiwania cryptomerioides

Seven new compounds were isolated from the leaves of Taiwania crypomerioides. Taiwaniaquinone D and taiwaniaquinone E are diterpenes having a six-five-six fused ring skeleton. Taiwaniadduct A is a [4 + 2] cycloaddition product of β-myrcene and taiwaniaquinone A. Taiwaniadduct B and taiwaniadduct C are isomers derived from [4 + 2] cycloadditions of trans-ozic acid and taiwaniaquinone A. Taiwaniadduct D is formally an ene reaction product of taiwaniadduct B. Taiwaniadduct E is a [5 + 2] cycloaddition product of taiwaniaquinone A and trans-ozic acid. The structure determination of these new compounds was based on spectral analyses and chemical transformation. A crystalline compound, prepared by bismethylation of taiwaniadduct D, was analysed by X-ray diffraction to establish the stereochemistry.

Sesquiterpenes from leaves of Cryptomeria japonica

Abstract Twenty-seven sesquiterpenes were isolated from leaves of Cryptomeria japonica . The new compounds included elem-1-en-4,11-diol, 11-acetoxyeudesman-4α-ol, eudesmane-5α,11-diol, 3-eudesmene-1β,11-diol, 1β-acetoxy-3-eudesmen-11-ol, 4-eudesmene-1β,11-diol, 1β-acetoxy-4-eudesmen-11-ol, 7-epi-γ-eudesmol, 7-epi-4-eudesmene-1β,11-diol, 1β-acetoxy-4(15)-eudesmen-11-ol. Their structures were determined by chemical and spectral methods.

Terpenoids from leaves of Calocedrus formosana

Abstract Besides six labdane-type diterpenes, three new compounds of geranyl trans -coumarate, epitorusolyl cis -coumarate and diterpenoid γ-hydroxybutenolide, were isolated from leaves of Calocedrus formosana .

Abietanes and kauranes from leaves of Cryptomeria japonica

Abstract Totarol, 14 abietanes, two secoabietanes and four ent -kaurane derivatives were isolated from the leaves of Cryptomeria japonica . The new compounds included 6,12-dihydroxyabieta-5,8,11,13-tetraen-7-one, 6β-hydroxyferruginol, 7α,8α-epoxy-6α-hydroxyabieta-9(11), 13-dien-12-one, (5 R ,10 S )-12-methoxyabieta-6,8,11,13-tetraene, ent -kaur-15-en-17-al and (+)-16-acetylkaurane-16,17-diol. Their structures were determined by chemical and spectral methods.

Terpenes from heartwood of Juniperus chinensis

Abstract A bisnorditerpene, 14 diterpenes and 12 sesquiterpenes were isolated from the heartwood of Juniperus chinensis . A new diterpene found (15-hydroxylabda-8(17),11 E ,13 E -trien-19-oic acid), and three new sesquiterpenes (cedr-3-en-15-ol, junipercedrol and α-longipinen-12-ol) were found. Junipercedrol, with a new skeleton, was determined to be 2,2,6,9-tetramethyltricyclo[5.2.2.0 3, 7 ]undecan-9-ol by spectral analyses and its stereochemistry was established by an X-ray analysis. This is also the first report in nature of thujopen-12-ol sesquiterpene.

Diterpenoids from leaves of Cryptomeria japonica

Phytol, seven labdanes, eight abietanes, four pimaranes and three biditerpenes were isolated from the leaves of Cryptomeria japonica. The new compounds included 8,13-dioxo-14,15,17-trinorlabdan-19-oic acid, 12-hydroxy-11-methoxyabieta-8,11,13-trien-7-one, 6α,11-dihydroxy-12-methoxyabieta-8,11,13-trien-7-one, 6,12-dihydroxy-11-methoxyabieta-5,8,11,13-tetraen-7-one, an acetal formed by abieta-8,11,13-triene-6α,7α,11,12-tetraol and imbricataloic acid, a self-condensation product of imbricataloic acid, as well as an acetal formed by abieta-8,11,13-triene-6α,7β,12-triol and 12-hydroxy-6,7-secoabieta-8,11,13-triene-6,7-dial. Their structures were determined by chemical and spectral methods.

Terpenes and lignans from leaves of Chamaecyparis formosensis

84 chemical constituents were isolated from the leaves of Chamaecyparis formosensis. These components include 18 sesquiterpenes, 40 diterpenes, 8 flavones, 7 lignans and 11 miscellaneous compounds. Among them 3 sesquiterpenes, 7 diterpenes and one lignan are new compounds, the structures of which were determined by chemical and spectral methods.

Serratene triterpenes from Pinus armandii bark

Abstract Five known serratene triterpenes, a nor -serratenone and four new serratene derivatives have been isolated from the bark of Pinus armandii .

Diterpenes from the bark of Juniperus chinensis

Abstract Eighteen diterpenes were isolated from the bark of Juniperus chinensis. The new compounds include the E-and Z-isomers of 12,15-dihydroxylabda-8(17),13-dien-19-oic acid, the E- and Z-isomers of 2α-hydroxycommunic acid as well as 15,16-bisnor-8,17-epoxy-13-oxolabd-11E-en-19-oic acid, whose structures were determined by spectral methods. An epoxy communic acid, 12,13-epoxylabda-8(17),14-dien-19-oic acid and the isomer of dihydroxy communic acid, 12,13-dihydroxylabda-8(17),14-dien-19-oic acid, were isolated for the first time from a natural source.