毕业设计论文化学系毕业论文外文文献翻译中英文

毕业设计论文 化学系 毕业论文 外文文献翻译 中英

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英文文献及翻译A chemical compound that is

contained in the hands of the problemsfor exampleCatalytic asymmetric

carbon-carbon bond formation is one of the most active research areas in

organic synthesis In this field the application of chiral ligands in

enantioselective addition of diethylzinc to aldehydes has attracted much

attention lots of ligands such as chiral amino alcohols amino thiols

piperazines quaternary ammonium salts 12-diols oxazaborolidines and

transition metal complex with chiral ligands have been empolyed in the

asymmetric addition of diethylzinc to aldehydes In this dissertation we

report some new chiral ligands and their application in enantioselective

addition of diethylzinc to aldehydes1 Synthesis and application of chiral

ligands containing sulfur atomSeveral a-hydroxy acids were prepared using

the literature method with modifications from the corresponding amino

acids valine leucine and phenylalanine Improved yields were obtained by

slowly simultaneous addition of three fold excess of sodium nitrite and

1 tnolL H2SO4 In the preparation of a-hydroxy acid methyl esters from

a-hydroxy acids following the procedure described by Vigneron a low yield

45 was obtained It was found that much better results yield 82 could

be obtained by esterifying a-hydroxy acids with methanol-thionyl

chlorideThe first attempt to convert S -2-hydroxy-3-methylbutanoic acid

methyl ester to the corresponding R

-11-diphenyl-2-mercapto-3-methyl-l-butanol is as the following S

-2-Hydroxy-3-methylbutanoic acid methyl ester was treated with excess of

phenylmagnesium bromide to give S -11-diphenyl-3-methyl-12-butanediol

which was then mesylated to obtain S -11-diphenyl-3-methyl-2-

methanesulfonyloxy -l-butanol Unfortunately conversion of S

-11-diphenyl-3-methyl-2- methanesulfonyloxy -l-butanol to the

corresponding thioester by reacting with potassium thioacetate under Sn2

reaction conditions can be achieved neither in DMF at 20-60 nor in

refluxing toluene in the presence of 18-crown-6 as catalyst When S

-1ll-diphenyl-3-methyl-2- methane sulfonyloxy -l-butanol was refluxed

with thioacetic acid in pyridine an optical active epoxide R

-22-diphenyl -3-isopropyloxirane was obtained Then we tried to convert

S -11-diphenyl-3-methyl-l2-butanediol to the thioester by reacting with

PPh3 DEAD and thioacetic acid the Mitsunobu reaction but we failed

either probably due to the steric hindrance around the reaction centerThe

actually successful synthesis is as described below a-hydroxy acid methyl

esters was mesylated and treated with KSCOCH3 in DMF to give thioester

this was than treated with phenyl magnesium bromide to gave the target

compound B-mercaptoalcohols The enantiomeric excesses of

p-mercaptoalcohols can be determined by 1H NMR as their S -mandeloyl

derivatives S -2-amino-3-phenylpropane-l-thiol hydrochloride was

synthesized from L-Phenylalanine L-Phenylalanine was reduced to the amino

alcohol S -2-amino-3-phenylpropanol Protection of the amino group using

tert-butyl pyrocarbonate gave S -2-tert

-butoxycarbonylamino-3-phenylpropane-l-ol which was then O-mesylated to

give S -2-tert-butoxycarbonylamino-3-phenylpropyl methanesulfonate

The mesylate was treated with potassium thioacetate in DMF to give

l-acetylthio-2-tert-butoxycarbonylamino-3-phenylpropane The acetyl

group was then removed by treating with ammonia in alcohol to gave S

-2-tert-butoxycarbonylamino-3-phenyl-propane-l-thiol which was then

deprotected with hydrochloric acid to give the desired S

-2-amino-3-phenylpropane-1-thiol hydrochlorideThe enantioselective

addition of diethylzinc to aldehydes promoted by these sulfur containing

chiral ligands produce secondary alcohols in 65-79 Synthesis and

application of chiral aminophenolsThree substituted prolinols were

prepared from the naturally-occurring L-proline using reported method

with modifications And the chiral aminophenols were obtained by heating

these prolinols with excess of salicylaldehyde in benzene at refluxThe

results of enantioselective adBelow us an illustration for

exampleN-Heterocyclic carbenes and L-Azetidine-2-carboxylic

acidN-Heterocyclic carbenesN-Heterocyclic carbenes have become

universal ligands in organometallic and inorganic coordination chemistry

They not only bind to any transition metal with low or high oxidation

states but also to main group elements such as beryllium sulfur and iodine

Because of their specific coordination chemistry N-heterocyclic carbenes

both stabilize and activate metal centers in quite different key catalytic

steps of organic syntheses for example C-H activation C-C C-H C-O and C-N

bond formation There is now ample evidence that in the new generation of

organometallic catalysts the established ligand class of

organophosphanes will be supplemented and in part replaced by

N-heterocyclic carbenes Over the past few years this chemistry has become

the field of vivid scientific competition and yielded previously

unexpected successes in key areas of homogeneous catalysis From the work

in numerous academic laboratories and in industry a revolutionary

turningpoint in oraganometallic catalysis is emergingIn this thesis

Palladium Ⅱ acetate and NN"-bis- 26-diisopropylphenyl dihydro-

imidazolium chloride 1 2 mol were used to catalyze the carbonylative

coupling of aryl diazonium tetrafluoroborate salts and aryl boronic acids

to form aryl ketones Optimal conditions include carbon monoxide 1 atm

in 14-dioxane at 100℃ for 5 h Yields for unsymmetrical aryl ketones

ranged from 76 to 90 for isolated materials with only minor amounts of

biaryl coupling product observed 2-12 THF as solvent gave mixtures of

products 14-Dioxane proved to be the superior solvent giving higher yields

of ketone product together with less biphenyl formation At room

temperature and at 0℃ with 1 atm CO biphenyl became the major product

Electron-rich diazonium ion substrates gave a reduced yield with

increased production of biaryl product Electron-deficient diazonium ions

were even better forming ketones in higher yields with less biaryl

by-product formed 2-Naphthyldiazonium salt also proved to be an effective

substrate givingketones in the excellent range Base on above palladium

NHC catalysts aryl diazonium tetrafluoroborates have been coupled with

arylboron compounds carbon monoxide and ammonia to give aryl amides in

high yields A saturated yV-heterocyclic carbene NHC ligand H2lPr 1 was

used with palladium II acetate to give the active catalyst The optimal

conditions with 2mol palladium-NHC catalyst were applied with various

organoboron compounds and three aryl diazonium tetrafluoroborates to give

numerous aryl amides in high yield using pressurized CO in a THF solution

saturated with ammonia Factors that affect the distribution of the

reaction products have been identified and a mechanism is proposed for

this novel four-component coupling reactionNHC-metal complexes are

commonly formed from an imidazolium salt using strong base Deprotonation

occurs at C2 to give a stable carbene that adds to form a a-complex with

the metal Crystals were obtained from the reaction of imidazolium chloride

with sodium t- butoxide Nal and palladium II acetate giving a dimeric

palladium II iodide NHC complex The structure adopts a flat 4-membered

ring u2 -bridged arrangement as seen in a related dehydro NHC complex

formed with base We were pleased to find that chloride treated with

palladium II acetate without adding base or halide in THF also produced

suitable crystals for X-ray anaysis In contrast to the diiodide the

palladium-carbenes are now twisted out of plane adopting a non-planar

4-ring core The borylation of aryldiazonium tetrafluoroborates with bis

pinacolatoborane was optimized using various NHC ligand complexes

formed in situ without adding base NN"-Bis 26-diisopropylphenyl

-45-dihydroimidazolium 1 used with palladium acetate in THF proved

optimal giving borylated product in 79 isolated yield without forming of

bi-aryl side product With K2CO3 and ligand 1 a significant amount of biaryl

product 24 was again seen The characterization of the palladium chloride

complex by X-ray chrastallography deL-Azetidine-2-carboxylic

acidL-Azetidine-2-carboxylic acid also named S -Azetidine-2-carboxylic

acid commonly named L-Aze was first isolated in 1955 by Fowden from

Convallaria majalis and was the first known example of naturally occurring

azetidine As a constrained amino acid S -Azetidine-2-carboxylic acid has

found many applications in the modification of peptides conformations and

in the area of asymmetric synthesis which include its use in the asymmetric

reduction of ketones Michael additions cyclopropanations and Diels-Alder

reactions In this dissertation five ways for synthesize S

-Azetidine-2-carboxylic acid were studied After comparing all methods the

way using L-Aspartic acid as original material for synthesize S

-Azetidine-2-carboxylic acid was considered more feasible All mechanisms

of the way"s reaction have also been studied At last the application and

foreground of S -Azetidine-2-carboxylic acid were viewed The structures

of the synthetic products were characterized by Thermal

Gravity-Differential Thermal Analysis TG-DTA Infrared Spectroscopy

IR Mass Spectra MS and 1H Nuclear Magnetic Resonance 1H-NMR

Results showed that the structures and performances of the products

conformed to the anticipation the yield of each reaction was more than

70 These can conclude that the way using L-Aspartie acid as original

material for synthesize S -Azetidine-2-carboxylic acid is practical and

effective杂环化合物生成中包含手性等问题如催化形成不对称碳碳键在有机

合成中是一个非常活跃的领域在这个领域中利用手性配体诱导的二乙基锌和醛

的不对称加成引起化学家的广泛关注许多手性配体如手性氨基醇手性氨基硫醇

手性哌嗪手性四季铵盐手性二醇手性恶唑硼烷和过渡金属与手性配体的配合物

等被应用于二乙基锌对醛的不对称加成中在本论文中我们报道了一些新型的手

性配体的合成及它们应用于二乙基锌对醛的不对称加成的结果1含硫手性配体

的合成和应用首先从氨基酸 缬氨酸亮氨酸苯丙氨酸 出发按照文献合成α-羟基

酸并发现用三倍量的亚硝酸钠和稀硫酸同时滴加进行反应能适当提高反应的产

率而根据Vigneron等人报道的的方法用浓盐酸催化从α-羟基酸合成α-羟基酸

甲酯时只能获得较低的产率改用甲醇-二氯亚砜的酯化方法时能提高该步骤的产

率从 S -3-甲基-2-羟基丁酸甲酯合成 R -3-甲基-11-二苯基-2-巯基-1-丁醇经

过了以下的尝试 S -3-甲基-2-羟基丁酸甲酯和过量的格氏试剂反应得到 S -3-

甲基-11-二苯基-12-丁二醇进行甲磺酰化时位阻较小的羟基被磺酰化生成 S

-3-甲基-11-二苯基-2- 甲磺酰氧基 -1-丁醇但无论将 S -3-甲基-11-二苯基

-2- 甲磺酰氧基 -1-丁醇和硫代乙酸钾在DMF中反应 20～60℃ 还是在甲苯中

加入18-冠-6作为催化剂加热回流都不能得到目标产物当其与硫代乙酸在吡啶

中回流时得到的不是目标产物而是手性环氧化合物 R -3-异丙基-22-二苯基氧

杂环丙烷从化合物 S -3-甲基-11-二苯基-12-丁二醇通过Mitsunobu反应合成硫

代酯也未获得成功这可能是由于在反应中心处的位阻较大造成的几奥斯塑手村

犯体的合成裁其在不对称奋成中肠左用摘要 成功合成疏基醇的合成路是将a-

轻基酸甲酷甲磺酞化得到相应的磺酞化产物并进行与硫代乙酸钾的亲核取代反

应得到硫酷进行格氏反应后得到目标分子p一疏基醇用p一疏基醇与 R 义一 一

甲氧基苯乙酞氯生成的非对映体经H侧NM吸测试其甲氧基峰面积的积分求得其

ee值 3一苯基一氨基丙硫醇盐酸盐从苯丙氨酸合成 斗3一苯基一氨基丙醇由

L一苯丙氨酸还原制备氨基保护后得到 习一3一苯基一2一叔丁氧拨基氨基一1

一丙醇甲磺酞化后得到 习一3一苯基一2一叔丁氧拨基氨基一1一丙醇甲磺酸

酷用硫代乙酸钾取代后得 匀一3-苯基一2一叔丁氧拨基氨基一1一丙硫醇乙酸

酷氨解得 习一3一苯基一2一叔丁氧拨基氨基一1一丙硫醇用盐酸脱保护后得

到目标产物 扔3一苯基屯一氨基丙硫醇盐酸盐 手性含硫配体诱导下的二乙基

锌与醛的加成所得产物的产率为65一79值为O井92手性氨基酚的合成和应用

首先从天然的L一脯氨酸从文献报道的步骤合成了三种脯氨醇这些手性氨基醇

与水杨醛在苯中回流反应得到手性氨基酚 手性氨基酚配体诱导下的二乙基锌与

醛的加成所得产物的产率为45一98值为0一90手性二茂铁甲基氨基醇的合成

和应用 首先从天然氨基酸 绿氨酸亮氨酸苯丙氨酸和脯氨酸 合成相应的氨基醇

这些氨基醇与二茂铁甲醛反应生成的NO一缩醛经硼氢化钠还原得到手性二茂铁

甲基氨基醇 手性二茂铁甲基氨基醇配体诱导下的二乙基锌与醛的加成所得产物

的产率为66一97下面我们举例说明一下例如含氮杂环卡宾和L-氮杂环丁烷-2-

羧酸含氮杂环卡宾含氮杂环卡宾已广泛应用于有机金属化学和无机配合物化学

领域中它们不仅可以很好地与任何氧化态的过渡金属络合还可以与主族元素铍

硫等形成配合物由于含氮杂环卡宾不但使金属中心稳定而且还可以活化此金属

中心使其在有机合成中例如C-H键的活化C-CC-HC-O和C-N键形成反应中有着十

分重要的催化效能现有的证据充分表明在新一代有机金属催化剂中含氮杂环卡

宾不但对有机膦类配体有良好的互补作用而且在有些方面取代有机膦配体成为

主角近年来含氮杂环卡宾及其配合物已成为非常活跃的研究领域在均相催化这

一重要学科中取得了难以想象的成功所以含氮杂环卡宾在均相有机金属催化领

域的研究工作很有必要深入地进行下去 本文研究了乙酸钯和NN双 26-二异丙

基苯基 -45-二氢咪唑氯化物1作为催化剂催化芳基四氟硼酸重氮盐与芳基硼酸

的羰基化反应合成了一系列二芳基酮并对反应条件进行了优化使反应在常温常

压下进行 一个大气压的一氧化碳14-二氧杂环己烷作溶剂100℃反应5h 不同芳

基酮的收率达7690仅有微量的联芳烃付产物 212 反应选择性良好当采用四氢

呋喃或甲苯作溶剂时得到含较多副产物的混合物由此可以证明14-二氧杂环己

烷是该反应最适宜的溶剂在室温或0℃与一个大气压的一氧化碳反应联芳烃变

成主产物含供电子取代基的芳基重氮盐常常给出较低收率的二芳基酮而含吸电

子取代基的芳基重氮盐却给出更高收率的二芳基酮及较少量的联芳烃付产物实

验证明2-萘基重氮盐具有很好的反应活性和选择性总是得到优异的反应结果在

此基础上由不同的芳基四氟硼酸重氮盐与芳基硼酸一氧化碳和氨气协同作用以

上述含氮杂环卡宾作配体与乙酸钯生成的高活性含氮杂环卡宾钯催化剂催化较

高收率地得到了芳基酰胺优化的反应条件是使用2mol的钯-H_2IPr 1五个大气

压的一氧化碳以氨气饱和的四氢呋喃作溶剂由不同的有机硼化合物与三种芳基

重氮盐的四组份偶联反应同时不仅对生成的多种产物进行了定 L-氮杂环丁烷

-2-羧酸L-氮杂环丁烷-2-羧酸又称 S -氮杂环丁烷-2-羧酸简称为L-Aze1955年

由Fowden从植物铃兰 Convallaria majalis 中分离得到成为第一个被证实的植

物中天然存在的氮杂环丁烷结构作为一种非典型的氨基酸已经发现 S -氮杂环

丁烷-2-羧酸可广泛用于对多肽结构的修饰以及诸如不对称的羰基还原Michael

加成环丙烷化和Diels-Alder反应等不对称合成中的多个领域 本文通过对 S -

氮杂环丁烷-2-羧酸合成路线的研究综述了五种可行的合成路线及方法通过比较

选用以L-天冬氨酸为初始原料合成 S -氮杂环丁烷-2-羧酸的路线即通过酯化反

应活泼氢保护格氏反应内酰胺化反应还原反应氨基保护氧化反应脱保护等反应

来合成 S -氮杂环丁烷-2-羧酸分析了每步反应的机理并对 S -氮杂环丁烷-2-

羧酸的应用及前景给予展望 通过热分析红外质谱核磁等分析手段对合成的化合

物的结构进行表征结果表明所得的产物符合目标产物所合成的化合物的结构性

能指标与设计的目标要求一致每步反应的收率都在70％以上可以判定以L-天冬

氨酸为初始原料合成 S -氮杂环丁烷的路线方案切实可行