A New Route to 2,7- and 7-Functionalized Labdanes

Hersel, Ulrich; Steck, Melanie; Seifert, Karlheinz

doi:10.1002/(sici)1099-0690(200004)2000:8<1609::aid-ejoc1609>3.0.co;2-2

Cited by 24 publications

(10 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The 2‐ and 3‐vinylfurans were prepared by known methods 23. All other precursors are described in the publications that deal with the synthesis of the HV products (see the Supporting Information for details).…”

Section: Methodsmentioning

confidence: 99%

Triarylphosphine Ligands with Hemilabile Alkoxy Groups: Ligands for Nickel(II)‐Catalyzed Olefin Dimerization Reactions. Hydrovinylation of Vinylarenes, 1,3‐Dienes, and Cycloisomerization of 1,6‐Dienes

Biswas

Zhang²,

Raya³

et al. 2014

Adv Synth Catal

View full text Add to dashboard Cite

Substitution of one of the phenyl groups of triphenylphosphine with a 2-benzyloxy-, 2-benzyloxymethyl- or 2-benzyloxyethyl-phenyl moiety results in a set of simple ligands, which exhibit strikingly different behaviour in various nickel(II)-catalyzed olefin dimerization reactions. Complexes of ligands with 2-benzyloxyphenyl-, 2-benzyloxymethylphenyl-diphenylphosphine (L5 and L6 respectively) are most active for hydrovinylation (HV) of vinylarenes, with the former leading to extensive isomerization of the primary 3-aryl-1-butenes into the conjugated 2-aryl-2-butenes even at −55 °C. However, 2-benzyloxymethyl-substituted ligand L6 is slightly less active, leading up to quantitative yields of the primary products of HV at ambient temperature with no trace of isomerization, thus providing the best option for a practical synthesis of these compounds. In sharp contrast, hydrovinylation of a variety of 1,3-dienes is best catalyzed by nickel(II)-complexes of 2-benzyloxyphenyldiphenylphosphine, L5. The other two ligands, 2-benzyloxymethyl-(L6) and 2-benzyloxyethyl-diphenylphosphine (L7) are much less effective in the HV of 1,3-dienes. Nickel(II)-catalyzed cycloisomerization of 1,6-dienes into methylenecyclopentanes, a reaction mechanistically related to the other hydrovinylation reactions, is also uniquely effected by nickel(II)-complexes of L5, but not of L6 or L7. In an attempt to prepare authentic samples of the methylencyclohexane products, nickel(II)-complexes of N-heterocyclic carbene-ligands were examined. In sharp contrast to the phosphines, which give the methylenecyclopentanes, methylenecyclohexanes are the major products in the (N-heterocyclic carbene)nickel(II)-mediated reactions.

show abstract

Section: Methodsmentioning

confidence: 99%

Triarylphosphine Ligands with Hemilabile Alkoxy Groups: Ligands for Nickel(II)‐Catalyzed Olefin Dimerization Reactions. Hydrovinylation of Vinylarenes, 1,3‐Dienes, and Cycloisomerization of 1,6‐Dienes

Biswas

Zhang²,

Raya³

et al. 2014

Adv Synth Catal

View full text Add to dashboard Cite

show abstract

“…Hispanone (208) is a labdane-type furanoditerpenoid isolated from Ballota saxitilis which has been proven to have potential anti-fungi and anti-inflammatory effects (Citoglu et al 1998). The total synthesis of hispanone was reported with (R)-carvone as starting material (Scheme 2) (Hersel et al 2000). The furan ring was connected by adding 3-(bromomethyl) furan with the presence of pyridinium chlorochromate (PCC).…”

Section: Type Icmentioning

confidence: 99%

Naturally occurring furanoditerpenoids: distribution, chemistry and their pharmacological activities

et al. 2016

View full text Add to dashboard Cite

Furanoditerpenoids are a special group of diterpenoids composing of one or more furan rings, which are rarely found in nature. This review aims to survey the various naturally occurring furanoditerpenoids and their pharmacological activities. A fairly large number of furanoditerpenoids have been reported from the families Euphorbiaceae, Fabaceae and Lamiaceae, and a few ones from the families Asteraceae, Codoniaceae, Dioscoreaceae, Fossombroniaceae, Jamesoniellaceae, Meliaceae, Menispermaceae, Olacaceae, Psathyrellaceae, Sapindaceae and Scapaniaceae. Their distribution correlates strongly with the taxonomic divisions. Most of these plants are widely used in traditional medicines, and furanoditerpenoids have therefore been disclosed with a wide range of bioactivities including anti-cancer, antiinflammation and anti-microorganism. To structure this review, the furanoditerpenoids were classified into seven types, including clerodane-type (Type I), labdane-type (Type II), cassane-type (Type III), abietane-type (Type IV), spongian-type (Type V), prenylbisabolane-type (Type VI) and miscellaneous type (Type VII). On the basis of 170 references, this review covers the distribution, phytochemistry, synthesis and pharmacological activities of furanoditerpenoids, describing 444 compounds. The information provided in this review might shed light on further research and development of furanoditerpenoids as potential therapeutic agents.

show abstract

“…The known diterpenoids, leopersin B (1), 15-epileopersin B (2), leopersin C (4), 15-epileopersin C (5), 13 and 14 are identified on the basis of physical ([a] D ), and 1 H-and 13 C-NMR data. 2,3,16,17) Air-dried aerial parts of L. heterophyllus were extracted with MeOH by percolation at room temperature. Concentration under reduced pressure yielded an extract, which was divided into n-hexane-, ethyl acetate-and 1-BuOH-soluble parts by sequential solvent partitioning with H 2 O. Bis-spirocyclic compounds 1-12, and compounds 13 and 14 were obtained by systematic fractionation of n-hexane-soluble fraction first over silica gel, then over reversed-phase octadecyl silica (ODS) gel, followed by preparative HPLC.…”

Section: )mentioning

confidence: 99%

New Bis-spirolabdane-Type Diterpenoids from Leonurus heterophyllus SW.

Giang

Sơn²,

Matsunami

et al. 2005

CHEMICAL & PHARMACEUTICAL BULLETIN

View full text Add to dashboard Cite

Leonurus heterophyllus SW. (family: Lamiaceae, syn. Labiatae) is used in Vietnamese traditional medicine for the treatment of menstruation and child delivery in gynaecology, high blood pressure, blood stasis, heart disorders, and dysentery.1) The rich distribution of bis-spirolabdane-type diterpenoids with variations of functionalities in the plants of the genus Leonurus was reported in the previous studies on chemical composition of L. persicus, 2-5) L. cardiaca, 6,7) and L. sibiricus. 8,9) Similarly, two prefuranic labdane-type diterpenoids were isolated from L. heterophyllus collected in Guangdong Province, China.10,11) However, a systematic chemical investigation on L. heterophyllus is necessary for reasons of chemotaxonomic interest. It is noteworthy that bis-spirocyclic labdane-type compounds are not confined to the Leonurus species, and so far have been found in the genera of Leonotis (Lamiaceae), 12) Marrubium (Lamiaceae), 12)Otostegia (Lamiaceae), 13) and Vitex (Verbenaceae). 14,15) In our present study, systematic extraction and isolation afforded twelve natural bis-spirolabdane-type diterpenoids (1-12), eight of which are new (3, 6-12), together with hispanone (13) and galeopsin (14). The known diterpenoids, leopersin B (1), 15-epileopersin B (2), leopersin C (4), 15-epileopersin C (5), 13 and 14 are identified on the basis of physical ([a] D ), and 1 H-and 13 C-NMR data. 2,3,16,17) Air-dried aerial parts of L. heterophyllus were extracted with MeOH by percolation at room temperature. Concentration under reduced pressure yielded an extract, which was divided into n-hexane-, ethyl acetate-and 1-BuOH-soluble parts by sequential solvent partitioning with H 2 O. Bis-spirocyclic compounds 1-12, and compounds 13 and 14 were obtained by systematic fractionation of n-hexane-soluble fraction first over silica gel, then over reversed-phase octadecyl silica (ODS) gel, followed by preparative HPLC. While compounds 3, 8, 13 and 14 were obtained in pure form, the other compounds were isolated as epimeric pairs 1/2, 4/5, 6/7, 9/10 and 11/12 at C-15 position. This phenomenon of the co-occurrence of C-15 oxygenated epimeric pairs has been frequently seen in many examples of bis-spirolabdanetype diterpenoids of the genus Leonurus. [2][3][4][5][6][7]9) Although the absolute configurations of 1-12 were not individually confirmed herein, they are probably of the same normal labdane-type diterpenoids on the basis of the co-occurrence with 13 and 14, since the formation of bis-spirotetrahydrofuranes involves only C-9 side chain. Additionally, compounds 1/2 and 4/5 were previously isolated from the same extraction fractions together with 4-b-hydroxymethylpregaleopsin, the absolute assignments of p-bromobenzoate derivative of which have been unambiguously determined by single-crystal X-ray crystallographic analysis.2) Therefore, the stereochemistry of 1-12 is suggested to be presented as in the normal series of labdane-type diterpenoids.Leoheteronone A (3) , including eight new, named leoheteronones A-E (3, 6, 8, 9, 11), 15-...

show abstract

A New Route to 2,7- and 7-Functionalized Labdanes

Cited by 24 publications

References 16 publications

Triarylphosphine Ligands with Hemilabile Alkoxy Groups: Ligands for Nickel(II)‐Catalyzed Olefin Dimerization Reactions. Hydrovinylation of Vinylarenes, 1,3‐Dienes, and Cycloisomerization of 1,6‐Dienes

Triarylphosphine Ligands with Hemilabile Alkoxy Groups: Ligands for Nickel(II)‐Catalyzed Olefin Dimerization Reactions. Hydrovinylation of Vinylarenes, 1,3‐Dienes, and Cycloisomerization of 1,6‐Dienes

Naturally occurring furanoditerpenoids: distribution, chemistry and their pharmacological activities

New Bis-spirolabdane-Type Diterpenoids from Leonurus heterophyllus SW.

Contact Info

Product

Resources

About