Xanthane sesquiterpenoids: structure, synthesis and biological activity

The aim of this review is to survey the naturally occurring xanthanes and xanthanolides, their structures, biological activities, structure–activity relationships and synthesis. There has been no comprehensive review of this topic previously. On the basis of 126 references, 112 compounds are summarized.     

Celastraceae sesquiterpenoids: biological activity and synthesis

Plant extracts of the Celastraceae have been used for centuries throughout South America and China as insect repellents and insecticides in traditional agriculture, and also for the treatment of a plethora of medical ailments from stomach complaints and fever to rheumatoid arthritis and cancer. Many of the medicinally interesting properties associated with these crude preparations have now been attributed to a large family of highly oxygenated sesquiterpenoids based on a tricyclic dihydroagarofuran skeleton. In this article, the structural diversity and range of biological activities associated with this intriguing class of natural products are examined with a view to stimulating interest in their total synthesis. Existing synthetic endeavours towards their synthesis are also evaluated.     

Synthesis of sesquiterpenoids of the drimane group from labdane diterpenoids

Data on the partial synthesis of enantiomerically pure sesquiterpenoids of the drimane group, including valuable biologically active natural compounds, from accessible labdane diterpenoids are surveyed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 896–913, May 1997.     

Pyranonaphthoquinones--isolation, biological activity and synthesis

A review of the isolation, biological activity and synthesis of pyranonaphthoquinones and closely related compounds is provided.     

2-Acylcycloalkane-1,3-diones. Occurrence in nature,biological activity,biogenesis, chemical synthesis

This review systematizes information on 2-acylcyclohexane-1,3-diones and 2-acylcyclopentane-1,3-diones isolated from natural sources. Questions of their biological and chemical synthesis, their natural functions, and the biological activity that they exhibit are discussed.Institute of Bioorganic Chemistry, Academy of Science of the Republic of Belarus 220141, Belarus', Minsk, ul. Zhodinskaya, 5/2. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 635–663, September–October, 1995. Original article submitted December 29, 1994.     

Distribution of drimane sesquiterpenoids and tocopherols in liverworts, ferns and higher plants: Polygonaceae, Canellaceae and Winteraceae species

The liverwort, Porella vernicosa complex produces a very hot tasting polygodial, a drimane-type sesquiterpene dialdehyde. The same compound has been isolated from two ferns, Thelypteris hispidula and Blechnum fluviatile, as well as from the higher plants Polygonum hydropiper, P. hydropiper f. purpurascens (Polygonaceae), Cinnamosma, Caspicodendron, Canella and Warburgia species (Canellaceae), and Pseudowintera colorata, Tasmannia lanceolata, Drimys and Zygogynum species (Winteraceae). In addition, the liverworts and higher plants which elaborate polygodial and its related pungent drimane dials contain a small amount of alpha-tocopherol, gamma-tocopherol or delta-tocotrienol. The present paper gives the results of a comparative study on the drimane-type sesquiterpenoids in some liverworts, ferns and higher plants, and the role of tocopherols in these plant groups.     

Synthesis of nitrogen-containing drimane sesquiterpenoids from 11-dihomodrim-8(9)-en-12-one

Products from the reaction of 11-dihomodriman-8α-ol-12-one with several reagents such as MeSO₃SiMe₃, CF₃SO₃SiMe₃, Sc(CF₃SO₃)₃, conc. H₂SO₄ in EtOH (30% solution), and Amberlist-15 ion-exchange resin were studied. 11-Dihomodrim-8(9)-en-12-one and its oxime were synthesized. The reaction of its oxime with H₃PO₄ (86%) or CF₃CO₂H produced (1S,2S,4aS,8aS)-2,5,5,8a-tetramethyldecahydro-1H-naphtho [1,2-e]-3-methyl-4,5-dihydro-[1,2,6]-oxazine; with p-TsCl in Py, (1S,2S,4aS,8aS)-2,5,5,8a-tetramethyldecahydro-1H-naphtho[1,2-d]-2-methylpyrroline-N-oxide; and with PCl₅ in Et₂O, 11-acetylaminodrim-8(9)-ene and 11-methylaminooxodrim-8(9)-ene.     

Occurrence, biological activities and synthesis of kaurane diterpenes and their glycosides

This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kaurane diterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiological methodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation by enzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed.     

Thienopyrimidines: synthesis, properties, and biological activity

Data on the methods for the synthesis of isomeric thienopyrimidine derivatives, their chemical transformations, and biological activities are systematized and analyzed. Emphasis is given to studies published over the last 10—15 years.     

Thienopyridines: synthesis, properties, and biological activity

The current state and prospects of development of the chemistry of isomeric thienopyridines (synthesis, chemical transformations, and biological activities) are analyzed. Particular attention is given to studies published in the last 10–15 years. Dedicated to Academician V. I. Minkin on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 847–885, April, 2005.     

Benzofuroxans: their synthesis,properties, and biological activity

The review provides a brief historical background for the establishment of structure of benzofuroxanes. Methods for their synthesis are summarized, and the chemical properties are described, which are splitted into two parts: reactions proceeding with a ring opening of the heterocycle, and those occuring with a participation of the isocyclic moiety. The biological activity of various representatives belonging to the benzofuroxan series is covered in details.

     

A complete 1H and 13C NMR data assignment for four drimane sesquiterpenoids isolated from Drimys winterii

From the bark of Drimys winterii Forst., the drimane derivatives drimendiol, polygodial, isotadeonal and isodrimeninol were isolated. Complete and unambiguous 1H and 13C NMR chemical shift assignments of these compounds were achieved by COSY experiments, 13C/1H shift correlation diagrams and NOE experiments. Isotadeonal and isodrimeninol were found for the first time in this plant species.     

Microwave-assisted synthesis,characterization and biological activity of novel pyrazole derivatives

A series of 1-(4-substitutedphenyl)-3-phenyl-1H-pyrazole-4-carbaldehydes 4a–l have been synthesized and tested for their biological activities. Formation of the pyrazole derivatives was achieved by treating with Vilsmeier-Haack reagent. The newly synthesized compounds were evaluated for their anti-inflammatory and analgesic activities compared to Diclofenac sodium as standard drug. Compounds 4g, 4i and 4k exhibited the maximum anti-inflammatory and analgesic activities. The detailed synthesis, spectroscopic and toxicity data are reported.     

Two dinuclear Schiff-base complexes: synthesis,characterization, and biological activity

Two complexes, [Zn₂L(µ-OAc)](ClO₄) (1) and [Mn₂L(OAc)₂]?·?4H₂O (2), were synthesized by [2?+?2] cyclo-condensation between 2,6-diformyl-4-fluorophenol and 1,3-propyldiamine in the presence of metal ions M(II) (M?=?Zn and Mn), and were characterized by chemical analyses, IR spectra, electrospray mass spectra, and X-ray determinations. The results show that 1 forms dimers through hydrogen bonding. In 2, lattice waters, forming a 1-D water chain, function as glue to form a 3-D supramolecular network through extended hydrogen bonding. pBR322 plasmid DNA can be transformed to nicked form in air by 1 or nicked and linear forms in air by 2. Moreover, their antibacterial activities against S. aureus were investigated using penicillin as reference system.     

2-Allyloxy/propargyloxypyridines: synthesis,structure, and biological activity

The alkylation (allylation and propargylation) of 3-cyano-6-dialkylamino-2-pyridones containing a d-annulated ring occurs at the oxygen atom. The structures of the starting compounds and their alkylation products were determined by X-ray diffraction. The neurotropic and antimicrobial activity of alkylation products was examined.