Search

Three new gymnomitrane sesquiterpenoids have been isolated from the liverwort Marsupella emarginata var. patens together with the known (−)-gymnomitrene and (−)-ar-curcumene. Their structures and absolute configurations have been determined on the basis of chemical and spectroscopic evidence as well as from the results of an X-ray analysis of a derivative. We also describe the ring expansion reaction of the gymnomitrane framework and the chemosystematics of the genus Marsupella.

A cell suspension culture of the liverwort Jungermannia subulata was established from callus tissue induced by culturing spores. From the suspension culture, three new ent-kaurane-type diterpenoids were isolated together with three previously reported ent-kaurane-type diterpenoids. Five ent-kaurane-type diterpenoids were isolated from the intact J. subulata, two of which were new compounds. Their structures were determined by spectroscopic methods, chemical reaction, and X-ray crystallographic analysis.

(±)-Vitrenal (1), a sesquiterpene aldehyde with a novel vitrane skeleton, was synthesized from a monoterpene piperitenone (2) by 12-step reactions in ca. 7% overall yield. 2-Formyl-isocarane, derived from 2 via (±)-isocaran-2-one was allylated stereospecifically and, after protection of the formyl group, the allyl chain was modified to a 4-methoxy-3-butenyl group. Acid treatment of the masked dialdehydic intermediate yielded 1 by concomitant deprotection and aldol condensation.

The structure and absolute configuration of a new cyclopentenone derivative, (+)-kjellmanianone, isolated from the brown alga Sargassum kjellmanianum has been determined as 5-carbomethoxy-5-hydroxy-3-methoxy-2-cyclopenten-1-one on the basis of the chemical and spectroscopic evidence and the X-ray analysis.

The structures and conformations of 6β,12β-dihydroxy-3E,7E-dolabelladiene 6-p-bromobenzoate and acetoxyodontoschismenol 3S,4S-epoxide have been established By X-ray crystallographic analysis. The original assignment of the stereochemistry at C-12 of (+)-acetoxyodontoschismenol has been revised.

A series of the enantiomeric sesquiterpenoids corresponding to the antipodos of those obtained from higher plants were isolated from the liverwort Riccardia jackii. This result is an additional example suggesting the special position taxonoinical of the liverworts in plant kingdom

The mass spectra of fifteen diterpenoids belonging to the new carbon skeletons of verrucosane, neoverrucosane and homoverrucosane are examined. From their spectra the relationship between fragmentation patterns and substituted modes of these diterpenoids is discussed.

The structures and absolute configurations of the two sesquiterpene aldehydes, (–)-isobicyclogermacrenal (1) and (–)-lepidozenal (2), which were isolated from the liverwort Lepidozia vitrea, have been determined on the basis of chemical and spectroscopic evidence to be (6R,7S)-6,11-cyclogermacra-1(10)-E,4E-dien-14-al and (6R,7S)-lepidoza-1 (10)E,4E-dien-14-al, consisting of the cis- and trans-10,3-bicyclic ring systems. The structure of the former (1) has been confirmed by a single-crystal X-ray analysis of its hydroxy derivative (7). The molecular conformations, biogenetical features, and biological activity are also described.

Five new dolabellane diterpenoids have been isolated from the liverwort Odontoschisma denudatum, and their structures and absolute configurations have been determined on the basis of 1H and 13C NMR evidence and chemical correlation.

Three new monoacetates of diterpene diols were isolated from Mylia verrucosa and the structures were determined as [2], [3] and [9] on the basis of chemical and spectral evidence.

The structure of dihydroxyverrucosane (I), a novel diterpene-diol isolated from the liverwort Mylia verrucosa has been determined from single-crystal X-ray analysis of the mono-p-bromobenzoate (II) by the heavy-atom method. The crystals were monoclinic, a= 6.670(1), b= 19.269(1), c= 10.379(1)A, β= 112.6(4)°, space group P21, Z= 2. Block-diagonal least-squares refinement based on 1 929 independent reflections converged to R 0.078. The absolute configuration was established by the anomalous dispersion effect. The molecule contains a 3,6,6,5-tetracyclic ring system in which ring B is considerably distorted by fusion with the cyclopropane ring A. Ring C adopts a chair conformation and ring D is a conformation somewhere between a half-chair and β-envelope.

The mono p-bromobenzoate of the diol derived from α-pompene has been studied by X-ray crystal structure analysis and determined to be 9-p-bromobenzoxy-8-hydroxy-1,2,6,8-tetramethyltricyclo[5.3.1.02,6]undecane. The crystals are of the orthorhombic space group P212121, a=46.53(2), b=12.20(2), c=7.39(2) A, Z=8, and hence there are two independent molecules per asymmetric unit. The structure was solved by the heavy-atom methods, and refined by block-diagonal least-squares calculations to a final R value of 0.103 for 2493 observed reflections. The structures of the two independent molecules in the asymmetric unit are quite similar. Both molecules contain a tricyclo[5.3.1.02,6]undecane ring in which three fused rings (cyclohexane, cyclopentane, and cyclopentane) are present. The overall configuration of these three fused rings can be described as a “cis” type. The conformation of the cyclohexane ring is of a chair form, and the two cyclopentane rings exhibit envelope forms. Based on the anomalous X-ray dispersi...

Three sesquiterpene phenols with an ent-herbertane skeleton have been isolated from the liverwort Herberta adunca, and the elucidation of their structures and absolute configurations has been achieved on the basis of the chemical and spectral evidence.

Three labdane type diterpene glycosides ( 1 , 2 and 3 ) with 6-deoxy-L-idose have been isolated from Aster spathulifolius Maxim. and their structures have been determined on the basis of chemical and spectral data.

The title compounds, key intermediates in the syntheses of (±)-vitamin D3 and (±)-erythro-juvabione, have been prepared in short steps using stereoselective cleavage reactions of the cyclopropane derivatives.

A sesquiterpene aldehyde, (−)-lepidozenal, having a novel trans-fused bicyclo[8.1.0]undecane carbon skeleton has been isolated from the liverwort Lepidozia vitvea, and its structure and absolute configuration have been shown to be (6S,7R)-lepidoza-1(10)E,4E-dien-14-al, on the basis of the chemical and spectral evidence.

Conformational analysis of the dolabellane diterpenoid, 6β-acetoxy-12β-hydroxydolabella-3E,7E-diene containing 1,5-undecadiene, has been achieved by means of molecular mechanics calculations, 1H NMR, and CD spectrometry. The epoxidation products of the diene can be rationalized in terms of the calculated equilibrium conformations.

A new dolabellane diterpenoid, (+)-acetoxyodontoschismenol, displaying antifungal properties, has been isolated from the liverwort Odontoschisma denudatum, and its structure, including the absolute configuration, has been determined as (1R,6R,11R,12S)-6-acetoxy-12-hydroxydolabella-3E,7E-diene on the basis of the chemical and spectroscopic evidence.

Two enantiomeric cuparene-type sesquiterpenoids, (R)-(−)-cuparene ( 1 ) and (R)-(−)-δ-cuparenol ( 2 ), have been isolated from the liverwort, Bazzania pompeana . The structures and absolute configurations of the two compounds have been determined.

13C NMR spectra of several 2,3-seco-alloaromadendrane-type acetyl hemiacetals were analysed and the structure of an additional plant growth-inhibitor was determined to be (+)-9α-acetoxyovalifoliene. The biological activity of the new compound is also described.

The structure and absolute configuration of (–)-taylorione, isolated from the liverwort, Mylia taylorii, was elucidated to be ent-1,10-seco-aromadendra-1(5),4(15)-dien-10-one (1) on the basis of chemical and spectral evidence.

Three new sesquiterpenoids were isolated from the liverwort Marsupella emarginata subsp. tubulosa. The structures and absolute configurations of the compounds have been shown to be (−)-marsupellone(1), (+)-marsupellol(2) and (+)-acetoxymarsupellone(3), containing an ent-longipinane skeleton, on the basis of chemical and spectral evidence.

A series of ent-sesquiterpenoids corresponding to the optical antipodes of those in higher plants have been isolated from the liverwort Marchantia polymorpha. These sesquiterpenoids provide yet another example of the peculiar stereospecificity of the biogenesis of the liverwort sesquiterpenoids and suggest a special taxonomic position of the liverworts in the plant kingdom.

Liverworts (Hepaticae) form a special group considered to be an early stage in the evolution of terrestrial plants, and produce terpenoids and/or aromatic compounds characteristic to the species as their major lipophilic constituents. During the last two decades many types of sesquiterpenoids have been obtained from the liverworts and most of the liverwort sesquiterpenoids are the enantiomeric forms corresponding to antipodes of those from higher plants [1-5]. However, few investigations have been conducted on diterpenoids of the liverworts: about twenty kinds of diterpenoids with acyclic [3, 6], labdane [7-9], pimarane [10], kaurane [11-15], clerodane [16], and dolabellane [17, 18] frameworks have been isolated from several liverworts. All of these carbon skeletons are known in other kinds of organisms. In general, the diterpenoids, distributed widely in plants, are classified by difference of the initial step in biogenetical cyclization of geranylgeranyl pyrophosphate: the first group is formed by a protoninitiated reaction at the double bond of the distal unit, in a manner similar to those for triterpenoids and steroids. Alternative path of diterpenoid biosynthesis has a similarity to that observed in sesquiterpenoids. Recently, several diterpenoids consisting of the new carbon skeletons, sacculatane [19-21], verrucosane [22-25], and neoverrucosane [26], have been isolated from the liverworts. In continuing our study on the diterpenoid constituents of liverworts, using as the diagnostic components to chemotaxonomy of the liverworts, we here isolated eight kinds of diterpenoids including two new compounds from

Mass spectra of pterocarpan derivatives (I∼VII) are recorded in Figs. 1∼5 and Tables 1∼6. The major fragmentation pathways of these compounds are shown in Scheme1. The results illustrate that the observed fragmentation patterns are of considerable utility in the application of mass spectro metry to structure elucidation in this series.

Two homologous series of n-paraffins and sec-alcohols from C20 to C34 or C35 were isolated a wax constituents of a liverwort, Isotachis japonica. In both series, odd-members were predominant compared with even-members: the ratio of the total amount of odd- to total amounts of even-members was 3·9 in the n-paraffin homologues, and 16·5 in the sec-alcohol homologues.

During the course of investigation on constituents of liver-worts, four sesquiterpenoids showing opposite rotation, (−)-longiborneol, (−)-α-longipinene, (−)-longifolene and (+)-α-himachalene, were isolated from a Japanese liverwort. By preparation of derivatives and application of physical methods the absolute configuration of (−)-longiborneol, the main component, was elucidated as an optical antipode (I) of (+)-longiborneol isolated from higher plants.

Two novel sesquiterpenoids have been isolated from the liverwort Plagiochila semidecurrens, and their structures and absolute configurations have been shown to be (1) and (2), ent-2,3-seco-alloaromadendrane derivatives.

The structure of a new ent-longipinane type of sesquiterpenoid, (−)-ent-12β-acetoxylongipin- 2(10)-en-3-one from the liverwort Marsupella aquatica, has been elucidated by spectroscopic and chemical methods.

A novel cabon skeletal diterpene diol isolated from the liverwort Mylia verrucosa has been shown to have the structure (1), containing a novel fused 3,6,6,5-tetracyclic ring system, on the basis of chemical and spectral evidence.

A sesquiterpenoid containing a novel carbon skeleton (+)-vitrenal, a plant-growth inhibitor, has been isolated from the liverwort Lepidozia vitrea and its structure and absolute configuration have been shown to be as in structure (2) on the basis of chemical and spectral evidence and X-ray analysis.

Five soluble carbohydrates, (−)- l -bornesitol, (−)- d -mannitol, (+)- d -glucose, (+)-sucrose and (+)-trehalose, have been isolated as their acetyl derivatives from the liverwort, Mylia taylorii. The absolute configuration of these carbohydrates is the same as that of sugars found in vascular plants, although the liverwort sesquiterpenoids are usually enantiomeric relative to those of vascular plants. The soluble carbohydrates in seven other liverwort species have also been analysed by HPLC.

Three new diterpenoids of the verrucosane class were isolated as minor constituents of the methanol extract of the liverwort Mylia verrucosa and their structures shown to be 2β,9α,13β-trihydroxyverrucosane,9α-acetoxy-2β,13β-dihydroxyverrucosane and 2β,13β-dihydroxy-9-oxoverrucosane.

The title compounds, key intermediates in the syntheses of (±)-vitamin D3 and (±)-erythro-juvabione, have been prepared in short steps using stereoselective cleavage reactions of the cyclopropane derivatives.

During the course of investigation on constituents of liver-worts, four sesquiterpenoids showing opposite rotation, (−)-longiborneol, (−)-α-longipinene, (−)-longifolene and (+)-α-himachalene, were isolated from a Japanese liverwort. By preparation of derivatives and application of physical methods the absolute configuration of (−)-longiborneol, the main component, was elucidated as an optical antipode (I) of (+)-longiborneol isolated from higher plants.

The bicyclic sesquiterpene (+)-bazzanene (I) was treated with formic acid to give the tricyclic sesquiterpene (±)-cyclobazzanene (II), which was shown to be a racemate of the novel sesquiterpene (II) by X-ray diffraction analysis of the p-bromobenzoate derivative.

A sesquiterpene alcohol (–)-myltaylenol with a novel carbon skeleton has been isolated from the liverwort Mylia taylorii, and its structure (3), including the absolute configuration, has been determined on the basis of chemical and spectroscopic evidence as well as X-ray analysis of the benzoate derivative (7).

Aus den Hexanextrakten vonPlagiochila acanthophylla subsp.japonica wurden (−)-Maalioxid und (+)-Cyclocolorenon isoliert. Diese Verbindungen sind enantromer zu denjenigen, die aus hoheren Pflanzen erhalten worden sind.

A new enantiomeric sesquiterpene alcohol named (–)-maalian-5-ol was isolated from the liverwort, and the structure and absolute configuration was determined to be the stereostructureI by chemical and spectral evidence.The authors express their gratitude to Dr H. Inoue, National Science Museum, for identification of the liverwort, and Prof. T. Tokoroyama, Osaka City University, for sending of the data of (–)--maaliene and (+)-selina-5,11-diene. Thanks are also due to the Ministry of Education for financial support of this work.

A novel sesquiterpene aldehyde, (−)-isobicyclogermacrenal, was isolated from Lepidozia vitrea, and its structure and absolute configuration were shown to be ent-isobicyclogermacren-14-al on the basis of the chemical and spectral evidence.

The structures of (−)-herbertenediol and (−)-herbertenolide, the new aromatic sesquiterpenoids with the ent-herbertane skeleton isolated from the liverwort Herberta adunca, have been determined on the basis of the chemical and spectral evidence.