The First Total Synthesis of Preverecynarmin

Preverecynarmin, isolated from a pennatulacean coral, has been synthesized from E,E-farnesol. The key steps are alkylation of the cyanohydrin trimethylsilyl ether 5 with the halide 6 , the regioselective epoxidation of the siloxyl ether 9 , and the intramolecular macrocyclization of the siloxyl ether 12 induced by Ti(0).     

Total Synthesis of (±)-Nimbonone and (±)-12-Ethyl-13-methoxy- 8,11,13-podocarpatriene

Most diterpenoids exhibit significant bioactivities, such as antidermatophytic, antibact- erial, and antioxidant. Although a large number of aromatic tricyclic diterpenoids have been isolated, there are a few of them having ethyl substituent. The synthesis of this type diterpenoids has been seldom reported. In order to further study the relationship between the structure and bioactivities of the diterpenoid, we extended the diterpene synthesis1,2,3. It is desirable to report herein the syn…     

First Total Synthesis of 1,2-Dehydronephthenol

The first total synthesis of 1,2-Dehydronephthenol (15-hydroxy-cembra-1,3,7,11-tetraene), a novel cembranoid diterpene, was accomplished starting from trans, trans-farnesol through seven steps in an overall yield of 17% by employing titanium-induced intramolecular keto aldehyde reductive olefination-coupling as the key macrocyclization step.     

First Total Synthesis of 12-Hydroxy-13-methylpodocarpa-9, 11, 13-trien-3-one

12-Hydroxy-13-methylpodocarpa-9, 11, 13-trien-3-one 9 was isolated from the twigs ofCroton salutaris1. Many diterpenes exhibit significant bioactivities, such as antibac-terial and antitumour and 9 has a rare structure. In order to study the relationshipb…     

Total Synthesis of (±)-Gelsemine

A complex molecular reorganization ( 1 → 2 ), a sequential anionic aza-Cope rearrangement and Mannich cyclization, and an unprecedented intramolecular Heck reaction of the tetrasubstituted double bond of a vinylogous carbamate are key steps in a new total synthesis of (±)-gelsemine ( 3 ). MOM=methoxymethyl, DBU=1,8-diazabicyclo[5.4.0]undec-7-ene.     

13-甲氧基-6-羟基钩勿烷-5,8,11,13-四烯-7-酮的首次全合成

以α-环柠檬醛(2)为A环合成子,以间甲氧基苄基氯(3)为C环合成子,经缩合及分子内环化反应得关键中间体6.经1H NMR测试发现化合物6为全顺式结构.化合物6经氧化得双羰基化合物7.将7用t-BuOK/t-BuOH处理后得到烯醇式结构的化合物8.最后将异丙基通过Fride1-Crafts反应一步引入得到目标产物1.     

The First Total Synthesis of 16-Hydroxygeranylgeraniol

Facile synthesis of 16-hydroxygeranylgeranio 1,a naturally occurring alicyclic diterpene,by alkylation reaction of allylic iodide 3 with phenyl sulfone 4,is described.     

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.     

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).     

(±)-19-去甲基-4(18),8,11,13-四烯-松香烷-7-酮的全合成

以间异丙基溴苯1为起始原料,通过进攻环氧乙烷及溴代两步制得溴化物3.溴化物3与Hagemann′s酯发生偶联反应,水解后生成偶联产物5.再以路易斯酸BF3·Et2O催化化合物5进行分子内环化为关键步骤得到反式稠合中间体6,最后通过与三苯基膦碘甲烷季盐发生Wittig反应及氧化,合成了(±)-19-去甲基-4(18),8,11,13-四烯-松香烷-7-酮[19-nor-abieta-4(18),8,11,13-tetraen-7-one](8).     

Total Synthesis of (±)-Celaphanol A

Celaphanol A was a diterpene isolated from the stems of Celastrus stephanotifolius1, which have been the subject of continued and growing interest, due to the range of biological activities shown by many members of this family2. Some have been used in traditional medicine3 or as a stimulant4 from ancient times. In order to further study the relationship between the structure and biological activity of the diterpene compound and as an extension of diterpenoid synthesis in our laboratory5, 6, …     

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.     

(±)-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 .     

大环二萜天然产物(±)-Sinulariol-A的全合成

以香叶醇为起始原料,经多步反应完成了西松烷型大环二萜类天然产物(±)-Sinulariol-A的全合成.合成的关键步骤是醛5与丙烯酸甲酯经改进的Morita-Baylis-Hillman加成以及二价铬诱导的烯丙基氯化物与醛的分子内加成环化     

Total Synthesis of (±)-Halomon by a Johnson–Claisen Rearrangement

The total synthesis of the polyhalogenated antitumour agent halomon ( 1 ) was accomplished with two novel transformations as key steps: a Johnson–Claisen rearrangement of a dichlorinated alkene for the preparation of the tertiary chlorinated C3 and a new rearrangement of bromohydrins for the regiospecific introduction of the bromine and chlorine atoms on C6 and C7, respectively.     

Total Synthesis of (±)-2-Pupukeanone

(±)-2-Pupukenone ( 4 ) has been synthesized, the key step being the intramolcular Diels-Alder reaction of the intermediate 13 to 14 (42%) and 15 (14%). The bromodiene 12 has been obtained from the reaction of α-isopropylidene-γ-lactone (Scheme 2) 12 with sodium phenylselenide and subsequent esterification to 9 , oxidation and thermal elimination of which furnished 10 . Reduction of 10 with diisobutylaluminimum hydride and treatment of the resulting alcohol 11 with PBr₃ led to the required bromodiene 12 . Finally, hydrogenation of the 14 on Pt(C) in CH₃OH gave a 4:1 mixture of 2-pupukeanone ( 4 ) and epi-2-pupukeanone 16 .     

(±)-12-乙基-13-甲氧基-8,11,13-罗汉松三烯-7-酮和(±)-12-乙基-13-甲氧基-8,11,13-罗汉松三烯的全合成

以α-环柠檬醛(1)为A环合成子,以季盐(2)为C环合成子,经缩合及分子内环化反应得到关键中间体(5).为引入乙基,进行了Friedel-Crafts反应和脱氧反应等,共经7步反应得到了(±)-12-乙基-13-甲氧基-8,11,13-罗汉松三烯-7-酮[(±)-nimbonone](9)及(±)-12-乙基-13-甲氧基-8,11,13-罗汉松三烯(10).     

The First Total Synthesis of 3-Oxo-11, 12, 13-trihydroxyeudesm-4-ene

The first total synthesis of 3-oxo-11, 12, 13-trihydroxyeudesm-4-ene, a highly oxygenated natural eudesmane, was described.     

Total Synthesis of (±)‐Eusiderin G and (±)‐Eusiderin M

(±)‐Eusiderin G and (±)‐Eusiderin M were first synthesized from pyrogallol, in which the Claisen Rearrangement was used to afford two important C₆‐C₃ units.