摘要:

A convenient synthesis of the naturally occurring α-amino acid pantonine, i.e. 2-amino-4-hydroxy-3,3-dimethylbutyric acid, was developed starting from 3-chloro-2,2-dimethylpropanal. Pantonine itself underwent cyclization into the corresponding γ-lactone by reaction with gaseous hydrogen chloride in methanol.

ISSN:1057-5634    

DOI:10.1080/10575639408043927

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Five hydroperoxysterols have been found in the ethereal extract ofArum italicumbesides further eleven oxygenated stigmasterols. The structures have been defined by chemical and spectroscopic studies. The possibility that some sterols are artifacts arising from autoxidation is considered.

ISSN:1057-5634    

DOI:10.1080/10575639408043928

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

From the leaves ofGelsemium elegansBenth. native to Thailand, two new iridoids, 7-deoxygelsemide (7) and 9-deoxygelsemide (9), were isolated as minor constituents together with known compounds, gelsemide (5) and gelsemiol (6).

ISSN:1057-5634    

DOI:10.1080/10575639408043929

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The photochemical rupture of methyl 14,15–dinor–13–oxo–7-labden–15–oate leads to a diene (methyl 7,9(11)–drimadien–12–oate) whose chemoselective epoxidation affords methyl 9α,11–epoxy–7–drimen–12–oate. Diastereoselective rearrangement with Lewis acids produces methyl 9R,11–oxo–7–drimen–12–oate, a precursor of poligodial and warburganal.

ISSN:1057-5634    

DOI:10.1080/10575639408043930

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Two new A-type proanthocyanidins were isolated fromPrunus spinosa. Its structures were elucidated by spectroscopy. We also included configurational studies based on DC and NMR data.

ISSN:1057-5634    

DOI:10.1080/10575639408043931

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Tiglic and angelic ester dihydro-β-agarofuran skeleton sesquiterpenes have been isolated fromMaytenus canariensis(Celastraceae) and their structures determined by spectroscopy. They underwent significant transformations on contact with silica gel or in solutions of CHCl3. The new sesquiterpenes were assayed againstSpodoptera littoralisin an election test and exhibited antifeedant activity.

ISSN:1057-5634    

DOI:10.1080/10575639408043932

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A combined reagent of DBU / bis(trimethylsilyl)acetamide (BSA) was highly effective for the simultaneous and rapid removal of two 2-cyano-1,1-dimethylethyl groups from a bis(2-cyano-1,1-dimethylethyl) thymidine 3′-phosphate derivative.

ISSN:1057-5634    

DOI:10.1080/10575639408043933

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A new elemanolide and two new heliangolides as well as (2R,3R)-(+)-3-hydroxy-2-methyl-butyrolactone have been isolated fromCentaurea paui. The structures were elucidated by high field NMR techniques and chemical transformation.

ISSN:1057-5634    

DOI:10.1080/10575639408043934

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A new diterpenoid bengalensol,ent-8(4→19)-abeo-3,18: 11α,1α-diepoxy-17-hydroxy-3,18-kauradien-2-one (4), has been isolated from the leaves ofCoffea bengalensis(Rubiaceae) and its structure assigned on the basis of its spectroscopic properties.

ISSN:1057-5634    

DOI:10.1080/10575639408043935

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Gastrolactone, a component from the larval defensive secretion of the chrysomelid beetleGastrophysa cyanea, was synthesized in four steps from citral. The key step was an enal-enamine [2+4] cycloaddition. Gastrolactol, the lactol form of plagiodial, was an intermediate in the synthetic sequence.

ISSN:1057-5634    

DOI:10.1080/10575639408043936

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor