从鹅去氧胆酸甲酯用简短和高立体选择性方法合成角鲨多胺

A short and highly stereoselective synthesis of squalamine (1) was accomplished in 9 steps from easily available methyl chenodeoxycholanate (2). The advanced intermediate 7α,24R-dihydroxy-cholestan-3-one (9) was synthesized by using improved dehydrogenation of 4 followed by conjugate reduction and efficient asymmetric isopropylation of aldehyde 7 as key reactions.     

Novel Stereoselective Synthesis of （E）-β-Silylvinylstannanes via Hydromagnesiation of Silylarylacetylenes

Hydromagnesiation of silylarylacetylenes 1 in diethyl ether gave(E)-β-silylvinyl Grignard reagents 2,whichreacted with trialkylstannyl chlorides 3 to afford stereoselectively(E)-β-silylvinylstannanes 4 in good yields.     

（E）-α-Bromovinylselenides as Convenient Precursors for Stereose-lective Synthesis of Trisubstituted Alkenes

Based on the different reactivity of selanyl and bromo groups,(E)-α-bromovinylselenides can undergo sequential cross coupling reactions with nucleophiles in the presence of transition metal complexes to form two carbon-carbon bonds in the same olefinic carbon leading to trisubstituted alkenes stereoselectively in good yields.     

Stereoselective Synthesis of （E）-α-Aryltellurenylvinyl-stannanes and Their Application in the Synthesis of Stereodefined Trisubstituted Alkenes

(E)-α-Aryltellurenylvinylstannanes have been synthesized stereoselectively via the hydrozirconation of alkynylstannanes, followed by the reactions with aryltellurenyl iodides. (E)-α-Aryltellurenylvinylstannanes can undergo sequential cross coupling reactions with both electrophiles and nucleophiles in the presence of transition metal complexes to form two carbon-carbon bonds in the same olefinic carbon leading to trisubstituted alkenes stereoselectively.     

A Short Synthesis of Clionamine D

Herein we describe a scalable four‐step preparation of α‐methylene‐γ‐lactone 3 from steroidal sapogenin. This method allowed a facile synthesis of clionamine D, a natural aminosteroid with potent autophagy bioactivity and unprecedented chemical structure.     

Simple Approach to the Highly Stereoselective Synthesis of trans-1,2-Cyclopropane Derivatives

In the presence of KF·2H2O, furoylmethyltriphenylarsonium bromide （1a） or thienoylmethyltriphenylarsonium bromide （1b） reacted with 2-[（un）substituted benzylidene]malononitrile （2） in chloroform at room temperature to give trans-3,3-dicyano-1-furoyl-2-[（un）substituted phenyl]cyclopropane （3a） or trans-3,3-dicyano-1-thienoyl-2- [（un）substituted phenyl]cyclopropane （3b） respectively in good yield with high stereoselectivity. The structures of product 3 were confirmed by IR, MS, 1^H NMR, 1^H-1^H COSY and microanalysis. The relative configuration of product 3 was determined by 1^H-1^H NOESY technique. The mechanism for the formation of product 3 was also proposed.     

Stereoselective Total Synthesis of Chrysanthemol

Recently,muchattentionhasbeenpaidtothesynthesisofbioactivenaturalproducts.Chrysanthemol,aneudesmanetypesesquiterpene,firstisolatedfromChrysanthemumindicumL.byD.Q.Yuetal.',showedstrongantiinflanunatoryactivityinmice.ThestructureandabsolutestereochemistryofchrVsanthemolwereelucidatedas1ThesyntheticrouteofchrysanthemolflomR-( )-carvoneisdepictedinScheme1:n.50%aqACOH,2hr;d)KOH,EtOH,oOC,3hr,e)Na,propanol,50"C,6hr,67.2%;66.7%i)m-CPBA/NaHCO3,CHZC12,r.t.,3.5hr,84%;TreatmentofR-( )-carvon…     

Iriomoteolide-1b中C(13)-C(23)片段的立体选择性合成

采用已知文献报道的化合物为起始原料,以不对称Evans-aldol反应和Julia-Kocienski成烯反应为关键步骤,对大环内酯化合物Iriomoteolide-1b的C(13)-C(23)片段结构进行了合成研究.全文使用普通而廉价的原材料或者试剂,采用常规的容易操作的反应条件,实验成本比较低,并且以13步13%的产率得到了C(13)-C(23)片段结构.     

高立体选择合成N,N''-取代-双-(反式-β,γ-二取代-γ-丁内酰胺)的简便方法

顺式－1－甲氧羰基－2－芳基－6，6－二甲基－5，7－二氧螺环[2，5]－4，8－辛二酮与联苯二胺（Ⅱ^0）或4，4'－亚甲基二苯胺（Ⅱ^1）在二氯甲烷中，40℃搅拌反应合成得到化合物Ⅲ^0 和Ⅲ^1，干燥后进一步在二甲苯中回流即可得到N，N－取代－双－（反式－β，γ－二取代－γ－丁内酰胺）（Ⅳ^0或Ⅳ^1），得率高，立体选择性好，方便简便。     

The Stereoselective Synthesis of Indoloquinolizines

Carboline was reduced with lithium aluminum hydride to provide carboline-alcohol whichreacted with methyl vinyl ketone to form the corresponding hydroxymethyl-amino-ketone. Underphase transfer condition it can be converted into enantiomerically pure indoloquinolizines. The cycliza-tion mechanism was also illustrated here.     

Stereoselective Synthesis of 1,3-Enynylstannanes via Palladium Catalyzed Cross-Coupling Reactions of （Z）-α-Bromovinylstannanes

Based on the different reactivity of stannyl and bromo groups, (Z)-α-bromovinylstannanes can undergo the cross-coupling reaction with alkynyl Grignard reagents in the presence of tetrakis(triphenylphosphine)palladium(0) catalyst in THF at room temperature to afford stereoselectively 1,3-enynylstannanes in good yields.     

氮叶立德高立体选择性地合成螺[环丙烷-1,4'-吡唑啉-5'-酮] 衍生物的研究

螺环丙基杂环化合物是一类具有重要药理、生理活性的化合物, 研究和发展这类化合物的新的立体选择性合成方法是当前有机合成领域的一个热点. 对1,4-二氮杂双环[2.2.2]辛环(DABCO)衍生的氮叶立德与3-甲基-1-苯基-4-芳亚甲基-5-吡唑啉酮合成螺环丙基吡唑啉酮的反应做了研究, 并与胂叶立德所参与的类似反应的结果做了比较, 发现仅得到单一反式结构产物, 但存在exo和endo两种构型, 其中前者为主要产物. 产物结构由IR, MS, 1H NMR, 13C NMR, 元素分析和X射线衍射鉴定. 还从反应机理角度对两种叶立德性质对反应的影响做了解释.     

Stereoselective Synthesis of (±) Neocnidilide

The lactone neocnidilide 8 occur in the roots of Cnidilide officinale1 which is shown to inhibit the growth and toxin production of mycotoxin-producing fungi2. Although The synthesis of lactones 7, which is stereoisomer of cnidilide, and 8 had been reported by others3, 4, we would like to report the highly stereoselective synthesis of its racemic isomer 8 as shown in Scheme 1. Scheme 1 COOHHOOCbcOOHH1234d5eOHOHHH 6fOOHHH 7g8COOHOHa12345673a7aOHHOH1235673 a7a1234561'1'2'…     

SmI2－Mediated Addition Reaction of α－Halomethylsulfones to Carbonyl Compounds. A Convenient Synthesis of β－Hydroxysulfones

Due to the chemoselective dehalogenation by SmI2, the addition of a-halomethylsulfones to carbonyl compounds afforded ,β-hydroxysulfones. Those reactions with α-bromomethylsulfones gave the products in moderate to good yields. The SmI2-mediated addition of gem-dihalomethylsulfones to ketones also afforded α-halo-β-hydroxysulfones in moderate yields.     

Highly Stereoselective Synthesis of trans-3-Aryl-4-carbethoxy-2,3-dihydro-2-fur-2＇-oyl-5-methylfurans

Multi-substituted dihydrofurans are valuable intermediates for the synthesis of natural products and pharmaceuticals. Considerable attention has been focused on the development of efficient and regioselective methods for their preparation. Using K2CO3 as a base, with the reaction of fur-2-oylmethyltriphenylarsonium bromide 1 and ethyl 2-acetyl-3-arylacrylate 2 in tetrahydrofuran at room temperature, we found an efficient protocol was achieved to synthesize trans-3-aryl-4-carbethoxy-2,3-dihydro-2-fur-2＇-oyl-5-methylfurans 3 in good yield with high stereoselectivity. The structure of compound 3 was confirmed by IR, ^1H NMR, MS and HRMS. The mechanism for the formation of 3 was proposed.     

Stereoselective Synthesis of Tetrahydropyran D-Ring of Methyl Sartortuoate

A stereoselective synthesis of functionalized tetrahydropyran D‐ring of methyl sartortuoate ( 1 ) was achieved starting from geraniol in a high yield. Sharpless asymmetric kinetic resolution, asymmetric dihydroxylation as well as asymmetric epoxidation were applied as key steps to establish all the four stereocenters of the D‐ring.     

New Stereoselective Synthesis of 4-Butyl-α-agarofuran

A potent anxiolytic 4-butyl-α-agarofuran (AF-5) was synthesized from ( )dihydrocarvone. Acid catalyzed hydration of ( )dihydrocarvone and interconversion with β-O-ketone 8 and the key intermediate α,β-unsaturated ketone 5 made this synthesis more practical.     

松毛虫性信息素前体(4Z,6E)-十一碳二烯醛的合成

从简单原料乙炔出发, 通过炔对丙烯醛的加成得到7-溴代-(4Z,6E)-庚二烯醛, 经乙二醇保护、Pd催化偶联、水解等步骤立体选择性地得到松毛虫性信息素前体(4Z,6E)-十一碳二烯醛.     

Three New Diterpenoids from Euphorbia wallichii

Three new abietane diterpene lactones, 3α-hydroxyjolkinolide A (1), ent-8α, 14β-dihydroxy-13(15)-ene-16(12α)-abietanolide (2) and ent-8α,14α-dihydroxy-13(15)-ene-16(12α)-abietanolide (3) as well as a known abietane diterpene jolkinolide A (4) were isolated from the roots of Euphorbia wallichii. Their structures were elucidated on the basis of spectroscopic analysis.