First total synthesis of(±)-sepicanin A

<正>A facile approach for the first total synthesis of naturally occurring geranylated flavanoids sepicanin A has been obtained with total yield 16%starting from 2,4,6-trihydroxyacetophenone after four steps.The key step was the protic acids(HCl or p-TsOH)-catalyzed benzopyrone formation in a protic polar solvent by deprotection and cycUzation of chalcone in one step.     

First total synthesis of （±）-malaysianone A and （±）-tanariflavanones B

A concise approach for the frst total synthesis of two naturally occurring flavanoids,（）-malaysianone A（1）and（）-tanariflavanones B（2）,has been accomplished with total yields of 12.9%and 10.4%,respectively.The key steps were regioselective deprotection and regioselective synthesis of 5-formaldehyde-8-hydroxy-2-[40-methyl-30-penteneyl]-dihydro-1-benzopyran（8）.     

First total synthesis of (±)-trolline

Trolline, a new bioactive alkaloid was isolated in 2004. We reported herein the first total synthesis of (±)-trolline, in two steps and 18.0% overall yield.     

THE SYNTHETIC ATTEMPT OF(±)-MALABARIC ACID AND(±)-ANISOMELOL——SYNTHE S IS OF PRECURSORS FOR(+)-MALABARIC ACID AND(±)-ANIOSMELOL

The precursors I(R′=CH_2OTHP,or CO_2Et)for(±)-Malabaric acid(1)and(±)-Anisomelol(2)were synthesized from geraniol 3 and homogeranyl iodide 5(2,6-dimetyl-9-iodo-2,6E-nonadiene)via Wadsworth-Emmons condensation and allylic regioselective chlorination.     

First total synthesis of four natural prenylated flavonoids

A facile approach for the first total synthesis of prenylated flavonoids,(±)-abyssinone-Vl-4-O-methyl ether 1,(±)-abyssinoneIV -4’-O-methyl ether 2,(±)-abyssinone-V-4’-O-methyl ether 3 and(±)-sigmoidin E 4 has been described.The key intermediate 4-hydroxy-3,5-di-(3-methylbut-2-enyl)benzaldehyde 6 was also first synthesized that features regioselective prenylation of 4-hydroxybenzaldehyde and crystallizing with petroleum ether from the reaction mixture by freeze-out effect.     

A novel and efficient total synthesis of(±)-Cembrene-A

(±)-Cembrene-A,a highly active scent-trail pheromone,was first isolated from thetermite(Nasutitermes exitiosus)and its structure was established by using chemical and spectralmethods,Afterwards,it was also found in some plants and soft corals.In view of itsbiological activity,some total syntheses have been reported.It was reported that its dl-form showed the same order of activity as that of the natural pheromone,In previous work,     

A practical stereoselective synthesis of (S)-( - )-ofloxacin

A very efficient and practical procedure for preparation of ( S)-( - )-ofloxacin has been developed (10 steps, overall yield ≥ 45 % ) . The key step of this approach is the regioselective nucleophilic substitution of 2-position fluorine atom of 2,3,4-tirfluoronitrobenzene by (S)-glycerol acetonide.     

Studies on Macrocyclic Diterpenoids (Ⅵ)——A Novel Synthetic Route to (±)-Cembrene-A

The total synthesis of(土)-cembrene-A, a termite pheromone, was achieved from geranylacetone and geraniol as starting materials. The key steps were the phase transfer catalyzed coupling reaction of sulphone (6) with chloride (9) and the intramolecular macrocyclization of dicarbonyl precursor (12) induced by low valent titanium. The synthetic route was short with anoverall yield of 17%.     

Efficient and Facile Synthesis of ( ± )-Salvirecognine

Salvirecognine (7) is a diterpene isolated from Salvia recognita[1] which has been the subject of continued and growing interest, due to the range of biological activities shown by many members of this family. [2] In order to study further relationships between the structure and biological activity of the diterpene compounds and as an extension of diterpenoid synthesis in our laboratory, [3,4] the first total synthesis of the title compound was achieved by an efficient and facile route (Scheme 1).     

First total synthesis of isoquinolinone alkaloid marinamide and its methyl ester

The first total synthesis of isoquinolinone alkaloid marinamide 1 and its methyl ester 2 was described. The key steps involved a regioselective Frieclel-Crafts reaction of 1-benzyl-1H-pyrrole to form the intermediate 8.     

First total synthesis of （±）-abyssinoflavanone V

The total synthesis of （±）-abyssinoflavanone V was first achieved through C-prenylation, selective protection of phenolic hydroxyl group, aldol condensation, cyclization and deprotection starting from cheap 4-hydroxybenzaldehyde and 2,4,6- trihydroxyacetophenone, with total yield 24%. All structures of new compounds were confirmed by IR, 1^H NMR and MS.     

STUDIES ON STEROIDAL PLANT-GROWTH REGULATORS (ⅩⅦ)——A NEW SYNTHESIS OF HOMOBRASSINOLIDE AND (22S,23S)-22,23-EPI-HOMOBRASSINOLIDE

Homobrassinolide (2) and (22S, 23S)-22,23-epi-homobrassinolide (4) were synthesized fromstigmasterol in seven steps respectively in 4.7% and 24.1% overall yields. The ratio of 2 to 4is 1:5. The key step is the highly regioselective formation of the B--homo-7-oxa-lactone ringby oxidation of an enol silyl ether with 3--chloro-peroxybenzoic acid.     

Orientation effects on C2(5)-C2'(5')linked bioxazole isomers synthesized via regioselective and sequential C—H arylation

Bis(4-fluorophenyl) substituted oxazole(2,5-Oxz) and C2(5)-C2'(5') linked bioxazole isomers(C2-C2'_BOxz,C2-C5'_BOxz and C5-C5'_BOxz) were concisely synthesized via palladium-catalyzed regioselective and sequential C-H arylation in 1-3 reaction steps along with 20%-83% of total yields from oxazole and4-bromofluorobenzene.The linking orientation plays a key role in the packing geometry and photophysical properties of C2-C2'_BOxz,C2-C5'_BOxz and C5-C5'_BOxz.These bioxazole isomers in solid state showed significant differences in photoluminescence quantum yields(PLQY)(0.33,0.25 and 0.04,respectively),delayed fluorescence properties and powder X-ray diffraction(PXRD) patterns,suggesting the divergence in intermolecular interactions.The theoretically calculated gradient isosurfaces and complexation energies indicate the existence of intense π-π interactions between molecular layers,which are in good agreement with the variation trend of optical properties.     

First Total Synthesis of (±)-13-Hydroxy-8 (14)-abietene

(±)-13-Hydroxy-8 (14)-abietene, a rare alicyclic diterpene possessing an isopropyl group and a hydroxy group at the C-13 position, was isolated from Solidago missouriensis nutt1. Many diterpenes exhibit significant bioactivities, such as antibacterial. As a part of our synthetic studies on the naturally-occurring diterpenes, we are attemping the synthesis of the rare natural compound. To our knowledge no total synthetic work has been reported yet. In order to study the further relationship b…     

STUDIES ON ANTIHEPATITIC DRUGS——TOTAL SYNTHESIS OF (±)SCHIZANDRIN C AND ITS ANALOGS

This paper reports the total synthesis of (±) schizandrin, C, namely S, 6, 7, 8-tetrahydro-1,12-dimethoxy-2, 3, 10, 11-bismethylenedioxy-6, 7-cis-dimethyldibenzo (a, c) cyclooctene (12B), a new active SGPT lowering principle isolated from the Chinese medical plant Schizandra chinensis, and its 6, 7-trans-dimethyl isomer (16B). We also synthesized two more isomers, namely 5, 6, 7, 8-tetrahydro-3, 10-dimethoxy-1, 2, 11, 12-bismethylenedioxy-6, and 7-cis-(and trans-) dimethyldibenzo (a, c) eyelooctene (12A and 16A). The NMR, UV and mass spectra of these four isomers are discussed. IR (in chloroform), UV, NMR and MS of synthetic schizandrin C (12B) are identical with those of the natural compound.     

A powerful approach to alkoxy radical-mediated remote C(sp~3)–H bonds functionalization

正The activation of inert C(sp~3)–H bonds with control of reactivity and selectivity is one of the central topics in chemical sciences.In this context,alkoxy radical-mediated 1,5-hydrogen atom transfer allows the regioselective transfor-     

A new shortcut synthesis route for (±)raphidecursinol

<正>The new shortcut synthesis route of(±)raphidecursinol 1,a racemic 8,4′-oxyneolignan compound,can be more easily achieved by the synthesis route,starting from readily available inexpensive 3,4,5-trimethoxybenzaldehyde and 1,2,3-trihydroxybenzene.All structures were confirmed by ~1H NMR,IR and MS.     

Cu(OTf)_2-catalyzed ring-opening of epoxides with anilines:A convenient synthesis of β-amino alcohols

The regioselective ring-opening of epoxides with aniline and p-chlorop niline catalyzed by copper(Ⅱ) triflate provides the corresponding β-amino alcohols in excellent yields.     

First Total Synthesis of (±)-3-(5-Hydroxy-4,7,8-trimethyl-3E,8-nonadiene)-△~2-butenolide

Compound 1, an unusual homosesquiterpene from the plant Gochnatia glutinosa grown in Argentina1. Its structure was determined by spectroscopic methods, however, the absolute configuration of C-8 and C-10 remained unsolved. As far as we know, neither biological activity nor a total synthesis of 1 has been reported. Here we wish to describe the first total synthesis of (?-1. Our synthetic route started from geraniol 2 as outlined in Scheme 1, and involved three key steps: (1) alkylation of …