Ussurienine,a novel 5α-cevanine alkaloid from fritillariaussuriensis maxim.

The structure of ussurienine, a novel 5α-cevanine alkaloid isolated from Fritillaria ussuriensis has been deduced as 1 from its NMR studies and confirmed by X-ray crystallographyic analysis.     

Sipe­imine,a steroidal alkaloid from Fritillariaroylei Hooker

In the title compound, 3,20-dihydroxycevan-6-one, C₂₇H₄₃NO₃, all the six-membered rings have normal chair conformations except ring D, which exists in a twist-chair conformation. The five-membered ring C adopts an envelope conformation. An O—H⃛O hydrogen bond connects the mol­ecules into spirals, which run along the b-axis direction.     

6-O-methylkrigeine, a new amaryllidaceae alkaloid from Nerine huttoniae Schönland

A novel Amaryllidaceae alkaloid, 6-O-methylkrigeine, has been isolated from Nerine huttoniae and the configuration was elucidated by 1-D and 2-D (1)H-NMR, (13)C-NMR, HRMS and optical rotation.     

A new alkaloid from Stemona sessilifolia

A new alkaloid, named sessilistemonamine D, was isolated from the roots of Stemona sessilifolia and the structure and relative configuration were determined on the basis of NMR and MS spectrometric data analysis.     

A new class of indole alkaloid ‘elegansamine’ constructed from a monoterpenoid indole alkaloid and an iridoid

Elegansamine (1) isolated from Gelsemium elegans (Thailand) was proved to be a new type of alkaloid composed by the carbon-carbon linkage of a monoterpenoid indole alkaloid and a monoterpene unit having the iridoid skeleton.     

12β-Acetyloxyperforatin,a New Limonoid from Harrisonia Perforata

A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11β-HSD1 enzyme.     

Nakinadine A, a novel bis-pyridine alkaloid with a β-amino acid moiety from sponge Amphimedon sp.

A novel cytotoxic bis-3-alkylpyridine alkaloid with a β-amino acid moiety, nakinadine A (1), has been isolated from an Okinawan marine sponge Amphimedon sp., and the structure and stereochemistry were elucidated by spectroscopic data.     

A new alkaloid from Castanea mollissima Blume

A new alkaloid, named 6-（2＇,3＇-dihydroxy-4＇-hydroxymethyl-tetrahydro-furan-1＇-yl）cyclopentadiene[c]pyrrole-1,3-diol, was isolated from the seeds of Castanea mollissima Blume. The structure was elucidated based on spectroscopic evidence including 2D NMR techniques.     

(±)-Quassidine K,a pair of cytotoxic bis-β-carboline alkaloid enantiomers from Picrasma quassioides

Abstract

(±)-Quassidine K (1), a pair of new bis-β-carboline alkaloid enantiomers, were isolated from Picrasma quassioides. Their structures were determined on the basis of detailed spectroscopic data analysis. The absolute configurations of (+)-S-quassidine K (1a) and (?)-R-quassidine K (1b) were determined by comparing with the reported experimental ECD spectra after chiral separation. The cytotoxicity assay showed activity against HeLa cells with IC50 values of 15.8 and 20.1?μM, respectively.     

“Anhydrolycaconitine”, a new diterpene alkaloid fromAconitum septentrionale K

A new alkaloid, anhydrolycaconitine (C₃₆H₄₆N₂O₉), was isolated from roots ofAconitum septentrionale K. Based on the results of¹H and¹³C NMR and IR spectroscopy and mass spectrometry of the alkaloid and the product of its alkaline hydrolysis and on the data of X-ray diffraction analysis of the hydrolysis product, the structure of 1α, 6β, 14α, 16β-tetramethoxy-7-oxo-18-succinylanthranoyloxy-17-(7→8)abeo-aconane was assigned to anhydrolycaconitine. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1640–1644, September, 2000.     

A new gluco indole alkaloid, 3, 4-dehydro-5-carboxystrictosidine, from Peruvian Uña de Gato (Uncaria tomentosa)

A new gluco indole alkaloid, 3,4-dehydro-5-carboxystrictosidine, was obtained from Peruvian U?a de Gato (Cat's Claw, original plant: Uncaria tomentosa) together with two known gluco indole alkaloids. This compound was the first example of isolation of a gluco monoterpenoid indole alkaloid having a 3,4-dihydro-beta-carboline ring system from nature. A characteristic feature of the compound was the quick replacement of the methylene hydrogens on C-14 with deuterium that was observed when it was dissolved in CD3OD. We demonstrated a similar proton-deuterium exchange on a model compound, 1-methyl-3,4-dihydro-gamma-carboline, in CD3OD solution.     

Synthesis of driman-8α,11-diol from sclareol through 8α,12-epoxy-14,15-bisnorlabdan-13-one

A four-step synthesis of driman-8,11-diol from sclareol in 44% total yield is described that includes the intermediates (12R)-8,12-epoxy-14,15-bisnorlabdan-13-one, (12S)-8,12-epoxy-12-acetoxy-13,14,15,16-tetranorlabdane and 8,12-epoxy-13,14,15,16-tetranorlabd-11-ene.Institute of Chemistry, Academy of Sciences of the Republic of Moldova, Kishinev, fax (3732) 73 97 75, Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 124–125, March–April, 2000.     

Syntheses of a new type of chiral phosphines from glucose

Methyl 3-deoxy-3-(diphenylphosphino)-4,6-O-benzylidene-α-D-altropyranoside (1) and methyl 2-deoxy-2-(diphenylphosphino)-4,6-O-benzylidene-α-D-altropyranoside (2) were prepared from methyl 2,3-anhydro-4,6-O-benzylidene-O-D-mannopyranoside and methyl 2,3-anhydro-4,6-O-benzyl-idene-α-D-allopyranoside,respectively,via regioselective and stcreospecific ring-opening reactions in high yields.Compounds 1 and 2 were oxidized to give the corresponding phosphine oxides (3 and 4).     

β-Carboline-type indole alkaloid glycosides from Ophiorrhiza trichocarpon

Six new β-carboline-type indole alkaloid glycosides, ophiorrhisides A–F (1–6), were isolated from Ophiorrhiza trichocarpon (Rubiaceae) collected in Thailand. Ophiorrhisides A (1) and B (2) possess a lactam function in the C ring and a unique biose residue in the molecule. Ophiorrhiside F (6) has a highly oxidized C ring with a 1,2-dicarbonyl function at C-5 and C-6 positions as well as a double bond between C-3 and C-14.     

A new veratramine alkaloid from the bulbs of Fritillaria hupehensis

A new highly conjugated alkaloid of veratramine type, 225,25S,5α-veratramine-7(8),12(14)-diene-3β,13β,23β-triol-6-one (1), was isolated from the bulbs of Fritillaria hupehensis Hsiao et K.C. Hsia. Its structure was determined on the basis of spectroscopic evidences.     

A taxane with a novel 9α,13α-oxygen bridge from Taxus cuspidata needles

A novel taxane with an unprecedented hemiacetal ring between C-13 and C-9 was isolated from the needles of Taxus cuspidata. The structure was characterized as (12αH)-2α,10β-diacetoxy-5α-cinnamoyloxy-9α,13α-epoxytax-4(20)-ene-11β,13β-diol (1). This is the first example of a natural taxane with a C-13 and C-9 oxygen bridge to form an unusual 6/8/6/6-membered ring system.     

Hydroacridines XXI [1]. 13C NMR Spectroscopic Investigation of the Stereoselectivities of Quaternizations of N-Alkyl Derivatives of (4aα,8aβ,9aβ,10aα)- and (4aα,8aα,9aβ,10aα)-Tetradecahydroacridine

Summary.  The stereoselectivities of the quaternization reactions of (4aα,8aβ,9aβ,10aα)- and (4aα,8aα,9aβ,10aα)-tetradecahydro-10-methylacridine with methyl- and ethyl iodide as well as those of (4aα,8aβ,9aβ,10aα)- and (4aα,8aα,9aβ,10aα)-10-ethyl-tetradecahydroacridine with methyl iodide were investigated using ¹³C NMR spectroscopy including ¹³C-labelling where appropriate. The methylations of both N-methyl amines occur by predominant (60% and 75%, respectively) equatorial approach, their ethylations occur sterospecifically by equatorial approach, and the methylations of the N-ethyl amines occur by highly stereoselective (> 90%) axial approach of the quaternizing reagent. Received October 27, 1999. Accepted November 22, 1999