摘要:

Five naphthalenedicarboxylic acids have been isolated from the aquatic plantEichhornia crassipes. The structures1–5have been attributed to their permethyiated derivatives on the basis of their spectroscopic features. A biogenetic correlation to phenalenes is suggested.

ISSN:1057-5634    

DOI:10.1080/10575639308050053

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:1057-5634    

DOI:10.1080/10575639308050054

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Six brominated pyrrole carboxylic acids, (3), (4), and (8) to (11), have been isolated and identified from an Australian marine sponge,Axinellasp. the structures of four new metabolites, (8) to (11), were secured by derivatization, spectroscopic analysis and synthesis. Two of these, (10) and (11), represent the first reported examples of naturally occurring tribromopyrrole carboxylic acids. the antibiotic properties of the natural products and synthetic analogues are presented. A revision of the structure of a known monobromopyrrole marine natural product, from (6) to (7), is also described.

ISSN:1057-5634    

DOI:10.1080/10575639308050055

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Hydroxyl functions of various thymidine and undine derivatives could be selectively and rapidly benzoylated without modification of the imide groups by means of phase transfer catalysis. the selectivity and reaction rate were highly dependent on the kind and concentration of alkali.

ISSN:1057-5634    

DOI:10.1080/10575639308050056

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The acid-catalyzed rearrangement of the 11α-acetoxy-9α-hydroxy derivative (8) of methyl (-)-kaur-9(11)-en-19-oate (1) afforded compound (2) the C/D ring system of which is analogous to that of antheridiogen, AAN, (3), the antheridium-inoucing factor from Anemiaphyllitidis.On the other hand, the rearrangement of the 9α,11α-dihydroxy derivative (9) under identical conditions led to a mixture of compounds (6) and (11). the 9α-hydroxy-11α-methanesulfonyloxy derivative (12) underwent a pinacolic-type rearrangement with potassium t-butoxide in t-butanol to give a ring B-homo derivative (13).

ISSN:1057-5634    

DOI:10.1080/10575639308050057

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We report here the synthesis of chiral PGE2methyl ester as a bissilyl etherviaStork intermediate, which involves the conjugate addition of lithium (E)-vinyldimethylzincate to 4-t-butyldimethylsiloxy-2-cyciopentenone followed by the formaldehyde trapping of the kinetic enolate to give eventually rise to a 2-methylenecyclopentanone derivative, the latter being subjected to the conjugate addition of another (Z)-vinylzincate.

ISSN:1057-5634    

DOI:10.1080/10575639308050058

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The aerial parts ofHaplophyllum thesioidesyielded a new alkaloid, thenaptosine [4,5-dimethoxy-11-metriylfuro(2,3-c)acridin-6(15H)-on] and a new coumarin, thesiolen (4-methoxyangelicin) in addition to known alkaloids, kokusaginine, skimmianine, pteleine, nkolbisine, heliparvifoline and flindersine as well as known coumarins, seseline, scaporon and angustifolin.

ISSN:1057-5634    

DOI:10.1080/10575639308050059

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

New and known combretastatins and their 2′-O-glucosides have been isolated from seeds ofCombretum kraussii(Hochst.) (Combreiaceae). They showedin vitrocytoxicity and influenced the tubulin polymerization.

ISSN:1057-5634    

DOI:10.1080/10575639308050060

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Propenylphenol plus allylphenol derived hydrobenzofuranoids, obtained by synthesis or from natural sources, are used to demonstrate evolution on the micromolecular level. Such neolignans carry sufficient information to instruct self-replication, as well as the replication of the other intermediates of cyclic reaction sequences. Modulation of temperature and acidity lead on to structural alternatives which compete with the intermediates of the cycles for starting material.

ISSN:1057-5634    

DOI:10.1080/10575639308050061

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Pancratium maritimum L.of Turkish origin has yielded two new crinine-type alkaloids, (-)-3β, 11α-dihroxy-1,2-dehydrocrinane (1) and (-)-8-Hydroxy-9-methoxycrinine (2). the alkaloids were separated using the combination of flash chromatography and preparative tic and purified by crystallization. Their structures have been determined by spectroscopic studies.

ISSN:1057-5634    

DOI:10.1080/10575639308050062

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor