(±)-Malaysianone A和(±)-Tanariflavanones B的全合成

以取代苯乙酮和5-醛基-8-甲氧甲氧基-2-甲基-2-(4'-甲基-3'-戊烯基)-二氢-1-苯并吡喃为原料,经羟醛缩合反应制得两个中间体——7,2',4'-三甲氧甲氧基-6'-羟基-2-甲基-2-(4'-甲基-3'-戊烯基)-二氢-1-苯并吡喃查尔酮(3a)和7,2',4'-三甲氧甲氧基-5'-异戊烯基-6'-羟基-2-甲基-2-(4'-甲基-3'-戊烯基)-二氢-1-苯并吡喃查尔酮(3b);3a经环合和脱保护基反应合成了(±)-Malaysianone A(4a),产率12.9%;3b经脱保护基和环合反应合成了(±)-Tanariflavanones B(4b),产率5.2%。4a和4b的结构经1H NMR,13C NMR和HR-ESI-MS确证。     

The Total Synthesis of (±)-13-Hydroxyneocembrene

(13S)-hydroxyneocembrene(18), a cembranoid which was isolated in 1988 from soft coral Sarcophyton trocheliophorum¹, has been shown to be an effective inductor of the release of labeled glucose from the lecithincholesterol liposomes and have cytostatic activities². The geometrical structure and absolute configuration of 18 have been defined to be 1S, 2E, 7E, 11E, 13S. Herein, we report the total synthesis of (±)-13hydroxyneocembrene(18).     

石松属生物碱Sieboldine A的全合成研究进展

简要介绍了石松属生物碱Sieboldine A的分离、生物活性及结构特征,综述了目前国内外对于Sieboldine A的全合成研究进展,详细论述了各个实验组在引入羟胺缩醛结构及构建cis-6/5稠环体系所采取的不同策略,并介绍了一价金催化的串联烯炔环化反应、路易斯酸催化的semipinacol重排和二碘化钐引发的自由基Pinacol偶联反应在Sieboldine A全合成中的应用。     

TOTAL SYNTHESIS OF(±)LESPEDEZAFLAVANONE-A

Lespedezaflavanone-A(1)was a new isoprene substituted flavanone which was isolated from, the root bark of Lespedeza davidii.In this paper, the total synthesis of its racemate(±)-1 was reported.     

First Total Synthesis of (±)-13-Hydroxyneocembrene

First total synthesis of (±)-13-hydroxyneocembrene ( 1 ), starting from 6-methyl-5-hepten-2-one ( 6 ) and geraniol ( 7 ), is described. The key steps are (i) the addition of sulfur-stabilized carbanion 12 to aldehyde 9 , (ii) the synthesis of 18 by using phase-transfer catalyzed coupling reaction, and (iii) low-valent titanium-induced intramolecular coupling of oxo aldehyde 3 to afford the target molecule after the final deprotection.     

(±)-Sinaiticin的首次全合成

首次完成了黄酮木脂素 (± ) -Sinaiticin的全合成 ,通过 9步反应 ,总产率为 1 3.4% ,cis-6发生差向异构化转化为 trans-7,氧化偶联为关键步骤 .     

First Total Synthesis of (±)Hedaol B

Abstract

Hedaol B, a new bisnorditerpene isolated from the Japanese brown alga Sargassum. sp., was first synthesized starting from geranyl acetone, alkylation of silyl cyanide as the key step.     

First Total Synthesis of (-)-Fumitremorgin C

The first total synthesis of the tremorgic mycotoxin furnitremorgin C (1a) employing 6-methoxy-N-hydroxytryptophan (5a) is presented. Our approach features formation of the nitrone (6a), stereoselective cycloaddition to yield 7a, ring opening and coupling with an L-proline derivative to form 14. Base-catalysed epimerisation gave 16, which was converted into the title compound by deprotection of the amine function, dioxopiperazine formation and dehydration.     

Facile Synthesis of (±)-2,6-Dimethethyl-6-hydroxy-2,7-octadienoic Acid and its Methyl Ester and Amide (Acacialactam)

The monoterpenoid acid 1, which is a component of some traditional medicine such as Gymnocladus chinensis baillon in glycoside form,¹ was recently isolated from Artemisia sieberi in Iran in free form.². Its structure has been established to be (E)-2,6-dimethyl-6-hydroxy-2,7-octadienoic acid (1) by chemical and spectroscopic analysis. Its methyl ester derivative 2,was isolated from the antibacterial extracts of the leaves of Piper aduncum³ as well. Acacialactam, a natural product isolated from the seeds of Acacia concinna DC.(Legunninosae) used in folk medicine of several tropical countries for treating some skin diseases, was assigned structure 4 by Sekine et al⁴ on the basis of its physical and spectral properties.     

First Total Synthesis of (−)‐Ligustiphenol

The first asymmetric total synthesis of (?)‐ligustiphenol is reported. The key step was conducted by exploiting a steric hindrance effect to control the formation of the adduct in a nucleophilic α‐Li‐phenolate addition reaction to the intermediate α‐oxo (?)‐menthyl ester. The synthesis is concise and feasible for the construction of analogous compounds and investigation of their biological activity.     

First Total Synthesis of an Analogue of (±)-Hypargenin B

Hypargenin B, a diterpene with the abietane skeleton, was isolated by Ayhan from the root of an endemic species salvia hypargenia and showed antibacterial activity1. In this diterpene, the junction of A/B ring is trans. In order to provide for studying further the relationship between the structure and bioactivities, we develop a novel route whereby the hypargenin B methyl ether 22 could be obtained in good yield. To our knowledge no total synthetic work has been reported on the title com…     

First Total Synthesis of Enantiomerically Pure(−)-Silphiperfol-6-en-5-on

The angular triquinane (?)-silphiperfol-6-en-5-on ((?)- 14 ) has been synthesized for the first time time in enantiomerically pure form. A highly efficient triplet-sensitized photoreaction, the oxadi-π-methane rearrangement of the complex β,γ-enone(+)- 6 to (?)- 7 , constitutes the key step. The know staring material, (1R, 7aR)-3,6,7,7a-tetrahydro-1-hydroxy-7a-methyl-1H-inden-5(2H)-one ((?)- 2 ), is readily accessible in > 97% enantiomeric purity. This new approach should enable access also to other angularly fused triquinanes of the silphinene type and related structures.     

(±)-Mesembrine的全合成

以3-乙氧基-2-环己烯酮羰基邻位芳基化反应与Tsuji-Trost反应的串联反应作为关键步骤来构筑季碳中心, 完成了番杏科生物碱Mesembrine的全合成. 从商品化原料出发经6步反应以17.8%的总收率合成得到(±)-Mesembrine.     

(±)-Palstatin的首次全合成研究

以廉价易得的5-溴香草醛和2,4,6-三羟基苯乙酮为起始原料，首次方便,高效地合成了(±)-Palstatin (1).合成的关键步骤为SeO₂促进的氧化环化和Ag₂O催化的氧化偶联反应.     

First Total Synthesis of (±)‐Celaphanol A

The first total synthesis of (±)‐Celaphanol A was accomplished starting from α‐cyclocitral and 3,4‐dimethoxy benzyl chloride in six steps. The intramolecular cyclization with BF₃·Et₂O and enolization in t‐BuOK/t‐BuOH were the key steps. The process of intramolecular cyclization afforded an all‐cis isomer intermediate for synthesis of aromatic tricyclic diterpenes.     

Total Synthesis of (±)-Iridolactone

A total synthesis of (±)-iridolactone ( 1 ) from bicyclo[2.2.1]ketone 6 is described. Trisubstituted cyclopentenoid aldehyde 7 is a key intermediate.