摘要:

The 15-thia-15-deoxy analogue of prostaglandin E1methyl ester has been prepared by the zirconocene chloride mediated conjugate addition of ann-pentyl ethynyl sulfide derived anion to an appropriately substituted cyclopentenone. Similar methodology has also been used to prepare other 3-(3′-thia-1′-octenyl)-cyclopentanones.

ISSN:0008-4042    

DOI:10.1139/v94-001

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Intermediates in the biosynthesis of blasticidin S and its nucleoside co-metabolites were detected by altering fermentation conditions. Inhibitors of specific types of biochemical reactions that were expected to be involved in blasticidin biosynthesis were fed toStreptomycesgriseochromogenes, in some cases with the inclusion of large quantities of the primary precursors of blasticidin S. The types of reactions and inhibitors used were (1) transaminase (aminooxyacetic acid and 2-methylglutamate), (2) amidotransferase (azaserine and 6-diazo-5-oxo-L-norleucine), (3) arginine biosynthesis (arginine hydroxamate), and (4) methyltransferase (ethionine). These manipulations apparently distorted the pools of precursors and (or) intermediates, and led to substantial accumulations of three known, previously minor, metabolites ofS.griseochromogenes, cytosylglucuronic acid, pentopyranine C, and demethylblasticidin S, and of two new ones, pentopyranone and isoblasticidin S. New cytosyl metabolites were detected by HPLC with photodiode array detection. Fermentations to which arginine hydroxamate and cytosine had been added also produced three aberrant metabolites that were derived from pentopyranone and arginine hydroxamate.

ISSN:0008-4042    

DOI:10.1139/v94-002

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

L-[3-13C]Phenylalanine andL-[3-13C]tyrosine were administered toMorusalbacell cultures, to produce intermolecular Diels–Alder type adducts of a prenylchalcone and a 2-arylbenzofuran such as chalcomoracin (1) as well as the adducts of two molecules of prenylchalcones such as kuwanon J (2) in high yields. The13C NMR spectra of1and2isolated from the cultures revealed that both amino acids were incorporated intact into chalcomoracin (1) and kuwanon J (2). This is the first example of direct NMR evidence for the almost equivalent incorporation of phenylalanine and tyrosine into the shikimate metabolites. This finding suggests the participation of a biosynthetic route from phenylalanine viatrans-cinnamate top-coumarate and from tyrosine top-coumarate in this plant.

ISSN:0008-4042    

DOI:10.1139/v94-003

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

1-(2-Bromobenzyl)-2-alkanesulfonylpyrroles (1c,1d) and 1-(4-bromobutyl)-2-methylsulfonfylpyrrols (8) undergo oxidative radical cyclization with partial or complete reductive desulfonylation to the pyrrolizidine derivatives5and9by an AIBN initiated reaction with tri-n-butyltin hydride. These cyclizations are suggested to proceed via a pseudo SRN1 process involving radical addition to the α position of the pyrrole nucleus not bearing the sulfonyl group. Reductive removal of the alkylsulfonyl moiety is proposed to occur in a second process after completion of the oxidative radical cyclization. The site of the radical addition is supported by deuterium labelling studies. Consistent with the timing of the loss of the sulonyl group is that 2-alkysulfonylpyrroles11are reductively desulfonylated under the same conditions that effect the oxidative radical cyclizations.

ISSN:0008-4042    

DOI:10.1139/v94-004

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Methodology for the preparation of isoquinoline derivatives fromN-(tert-butoxycarbonyl)-2-methylbenzylamines (1) was developed. Conversion of1to the dilithio species followed by condensation with DMF afforded Boc-3-hydroxy-1,2,3,4-tetrahydroisoquinolines3, which could be dehydrated to 1,2-dihydroisoquinolines4. Hydrogenation of dihydro compounds4afforded the corresponding tetrahydroisoquinolines5. Treatment of the dilithio species from1withN-methoxy-N-methylamides afforded ketones14, which were converted to 3-substituted dihydro-isoquinoline15, tetrahydroisoquinolines (16,17), or isoquinolines (20).

ISSN:0008-4042    

DOI:10.1139/v94-005

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Three β,β,β′,β′-2H4-labelled α,ω-diamines were synthesized and incubated with pea seedling diamine oxidase. The aminoaldehydes formed by oxidative deamination cyclized to the corresponding imines, which were trapped with benzoylacetic acid. In all three cases the acetophenone derivatives produced were shown by NMR and mass spectrometry to contain four deuterium atoms. The retention of all four deuterium atoms demonstrates that oxidative deamination of α,ω-diamines catalyzed by pea seedling diamine oxidase does not involve an enamine intermediate as previously suggested.

ISSN:0008-4042    

DOI:10.1139/v94-006

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

α-Guaiacoxylacetoveratrone, 1, was selected as a model of a lignin structure component for photolysis and free radical spin trapping studies. The 3,4-dimethoxyphenacyl radical, Ar-COĊH2, 2, thermally generated from α-bromoacetoveratrone with trimethyltin, was spin trapped by phenyl-tert-butylnitrone (PBN), and the spin-trapped radical identified by ESR and mass spectroscopy. Spin trapping by PBN of radical photoproducts from 1 gave a mixture of trapped radicals, according to ESR. These were separated as their hydroxylamines and identified by liquid chromatography/mass spectroscopy (LC/MS) under chemical ionization (CI) conditions. This LC/MS (CI) method identified the same phenacyl fragment, 2 (reduced), as well as a fragment tentatively attributed to a spin-trapped guaiacoxyl radical, chemically reduced to the hydroxylamine. Extended direct photolysis of 1 yields colored paramagnetic oligomers. The synthesis of 1-(3,4-dimethoxyphenyl)-2-(4-hydroxy-3-methoxyphenylethanone(10), a rearranged, recombination photoproduct of 1, is described. A pathway for formation of oligomers as unstable dimers of 10 is presented

ISSN:0008-4042    

DOI:10.1139/v94-007

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

A synthesis of the tricycle19has been completed in 14% overall yield from guaiacol. Several chemical transformations of this compound including its reduction to an octahydro naphtho[1,8-bc]furan and conversion to the hitherto unknown azuleno-[8,1-bc]furan ring system are described.

ISSN:0008-4042    

DOI:10.1139/v94-008

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

From cell suspension cultures ofRauwolfiaserpentinaBenth. a new enzyme activity was isolated and its properties determined. The enzyme is a soluble protein and catalyzes the transfer of a glucose moiety from UDPG to a wide variety of phenolic compounds withp-nitrophenol as one of the best substrates (Km = 1.21 mM, UDPG = 0.54 mM). In contrast to the membrane-bound UDPG: vomilenine-21-OH-β-D-glucosyltransferase fromRauwolfiaserpentinacells, this enzyme is not able to glucosylate indole alkaloids. The enzyme activity has been detected in 14 callus cultures belonging to 10 different plant families.

ISSN:0008-4042    

DOI:10.1139/v94-009

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

The known isomerization of the tricyclo[5.3.1.01,5]- to the [6.3.0.01,5]undecane skeleton by β-homoenolization led to examination of 2,9,9-trimethyl-6-methoxymethyltricyclo[5.3.1.01,5]undecanone (6) as a potential precursor for the synthesis of pentalenene, a naturally occurring sesquiterpenoid, utilizing a β-enolate rearrangement as a key step. While the anticipated rearrangement of6occurs, it is a minor process. The major rearrangement product arises by generation of a γ-enolate intermediate from a tricyclic enone formed by loss of methanol from6. This constitutes a new route to [3.3.3]propellanes and provides a third example of γ-enolate rearrangement. Structures of the products were established primarily from their1H and13Cmr spectra.

ISSN:0008-4042    

DOI:10.1139/v94-010

出版商:NRC Research Press    

年代:1994

数据来源: NRC