化學(xué)專業(yè)外語有機(jī)合成中保護(hù)基的作用-課件

化學(xué)專業(yè)外語有機(jī)合成中保護(hù)基的作用詞匯ProtectiveGroup、保護(hù)基multifunctionalpoundreactivesite、反應(yīng)活性部位sideproduct、副產(chǎn)物Reduction、oxidation

carbohydrate[?kɑ:b?u?haidreit]碳水化合物electrochemistry[i?lektr?u‘kemistri]電化學(xué)photolysis[f?u't?lisis]光分解、光解作用【課文翻譯】Whenachemicalreactionistobecarriedoutselectivelyatonereactivesiteinamultifunctionalpound,otherreactivesitesmustbetemporarilyblocked、selectively[si?lektivli]有選擇地反應(yīng)活性部位當(dāng)一個(gè)化學(xué)反應(yīng)將要在多功能化合物中的一個(gè)反應(yīng)活性部位有選擇的進(jìn)行時(shí),其它的活性部位必須是暫時(shí)地受阻(不反應(yīng))。1、PropertiesOfaProtectiveGroup保護(hù)基的性質(zhì)Manyprotectivegroupshavebeen,andarebeing,developedforthispurpose、[pr??tektiv]保護(hù)的、防護(hù)的許多保護(hù)性基團(tuán)差不多以及正在因此而發(fā)展起來。Aprotectivegroupmustfulfillanumberofrequirements、fulfill[ful?fil]履行、實(shí)現(xiàn)、完成一個(gè)保護(hù)性基團(tuán)必須能夠?qū)崿F(xiàn)大量的需要。Itmustreactselectivelyingoodyieldtogiveaprotectedsubstratethatisstabletotheprojectedreactions、selectively[si?lektivli]有選擇地、protected[pr??tektid]保護(hù)、substrate[?s?b?streit]底物、基質(zhì)、project[pr??d?ekt]計(jì)劃、設(shè)計(jì)它必須能夠以較高的產(chǎn)率進(jìn)行選擇性反應(yīng)而給出一個(gè)被保護(hù)的底物,這個(gè)底物關(guān)于所計(jì)劃的反應(yīng)表現(xiàn)穩(wěn)定。Theprotectivegroupmustbeselectivelymovedingoodyieldbyreadilyavailable,preferablynontoxicreagentsthatdonotattacktheregeneratedfunctionalgroup、available[??veil?bl]可用的、有效的、preferably[?pref?r?bli]更適宜、nontoxic[n?n?t?ksik]無毒的、regenerate[ri?d?en??reit]再生的、使再生保護(hù)性基團(tuán)必須能夠以較高的產(chǎn)率通過有效的,更適宜的、無毒的、不進(jìn)攻重新產(chǎn)生的功能基團(tuán)的試劑而進(jìn)行選擇性轉(zhuǎn)移(能上能下)。Theprotectivegroupshouldformacrystallinederivative(withoutthegenerationofnewchiralcenters)thatcanbeeasilyseparatedfromsideproductsassociatedwithitsformationorcleavage、[?krist?lin]結(jié)晶性、結(jié)晶度、[di?riv?tiv]衍生物、[?t?ir?l]手(征)性的、[?kli:vid?]分解、裂解 保護(hù)性基團(tuán)應(yīng)該能夠結(jié)晶(沒有產(chǎn)生新的手性中心),以便于與與其形成或分解相關(guān)的副產(chǎn)物分離。Theprotectivegroupshouldhaveaminimumofadditionalfunctionalitytoavoidfurthersitesofreaction、minimum[?minim?m]最低限度、最小量additional[??di??nl]額外的、附加的functionality[?f??k????n?liti]功能保護(hù)性基團(tuán)應(yīng)該具有最低的附加功能以幸免更多的部位(結(jié)合點(diǎn))反應(yīng)。

Sinceafewprotectivegroupscannotsatisfyallthesecriteriaforelaboratesubstrates,criteria[krai'ti?ri?]標(biāo)準(zhǔn)elaborate[i?l?b?reit]精巧的、精巧的substrate[?s?b?streit]底物、基質(zhì)因?yàn)橐恍┍Ｗo(hù)性基團(tuán)不能滿足所有精巧的底物的標(biāo)準(zhǔn),2、HistoricalDevelopment、發(fā)展歷史alargenumberofmutuallyplementaryprotectivegroupsareneededand,indeed,arebeingavailable、mutually[?mju:t?u?li]互相地、plementary[?k?mpl??ment?ri]補(bǔ)充的、補(bǔ)足的、available[??veil?bl]有效的因此需要大量互相補(bǔ)充的保護(hù)性基團(tuán),實(shí)際上,這些保護(hù)性基團(tuán)是有效的。Inearlysynthesesthechemistchoseastandardderivativeknowntobestabletothesubsequentreactions、syntheses['sinθ?si:z]合成、合成反應(yīng)derivative[di?riv?tiv]衍生的、衍生物subsequent[?s?bsikw?nt]后來的、隨后的、作為結(jié)果而發(fā)生的在早期的合成中,化學(xué)家選擇一個(gè)已知的對(duì)隨后的反應(yīng)穩(wěn)定的標(biāo)準(zhǔn)衍生物。Otherclassicalmethodsofcleavageincludeacidichydrolysis(eq、1),reduction(eq、2),andoxidation(eq、3):classical[?kl?sik?l]經(jīng)典的、傳統(tǒng)的、cleavage[?kli:vid?]分裂、acidic[??sidik]酸性的、hydrolysis[hai?dr?lisis]水解其它的傳統(tǒng)分解方法包括酸解(方程式1)、還原反應(yīng)(方程式2)、和氧化反應(yīng)(方程式3)。Someoftheoriginalworkinthecarbohydrateareainparticularrevealsextensiveprotectionofcarbonylandhydroxylgroups、carbohydrate[?kɑ:b?u?haidreit]碳水化合物、糖類、extensive[iks?tensiv]廣泛的特別是碳水化合物方面的一些原始性(獨(dú)創(chuàng)性)工作展現(xiàn)了對(duì)羰基和羥基基團(tuán)的廣泛保護(hù)作用。Forexample,acyclicdiacetonideofglucosewasselectivelycleavedtothemonoacetonide、diacetonide[dai'?sit?naid]二丙酮化物、glucose['ɡlu:k?us]葡萄糖、cleaved[k'li:vd]割開、monoacetonide['?sit?naid]單丙酮化物例如,葡萄糖的一種環(huán)狀二丙酮化物能夠選擇性裂解成單丙酮化物。Amorerecentsummarydescribestheselectiveprotectionofprimaryandsecondaryhydroxylgroupsinasynthesisofgentiobiose,carriedoutinthe1870s,astriphenylmethyl(三苯甲基)ethers、gentiobiose[d?en?i?'bai??s]龍膽二糖ether[?i:θ?(r)]醚、最近的一篇文章概括地描述了在19世紀(jì)七十年代進(jìn)行的合成龍膽二糖過程中以及在合成三苯甲基醚過程中,對(duì)伯羥基和仲羥基基團(tuán)的選擇性保護(hù)作用。Aschemistsproceededtosynthesizemoreplicatedstructures,theydevelopedmoresatisfactoryprotectivegroupsandmoreeffectivemethodsfortheformationandcleavageofprotectedpounds、在進(jìn)行合成更復(fù)雜結(jié)構(gòu)的同時(shí),化學(xué)家發(fā)展了更令人滿意的保護(hù)基和更有效的形成和分解被保護(hù)化合物的方法。3、DevelopmentofNewProtectiveGroups、新保護(hù)基的發(fā)展Atfirstatetrahydropyranyl(四氫吡喃基)acetalwasprepared,byanacid-catalyzedreactionwithdihydropyran,toprotectahydroxylgroup、pyranyl[‘pir?nil]吡喃基、acetal[‘?sit?l]乙縮醛、乙醛縮二乙醇、catalyze['k?t?laiz]催化pyran['pair?n]吡喃首先,通過二氫吡喃的酸催化反應(yīng)制備了四氫吡喃基乙縮醛來保護(hù)羥基。Theacetalisreadilycleavedbymildacidhydrolysis,butformationofthisacetalintroducesanewchiralcenter、acetal['?sit?l]乙縮醛、乙縮醛二乙醇cleaved[k'li:vd]劈開、剁開、割開hydrolysis[hai?dr?lisis]水解introduce[?intr??dju:s]介紹;引進(jìn)chiral[?t?ir?l]手(征)性的乙縮醛特別容易被中等強(qiáng)度的酸水解,然而乙縮醛的形成引進(jìn)了一個(gè)新的手性中心。Formationofthe4-methoxytetrahydropyranylacetaleliminatesthisproblem、pyranyl['pir?nil]吡喃基acetal['?sit?l]乙縮醛、乙縮醛二乙醇eliminate[i?limineit]排除、消除4-甲氧基四氫吡喃基乙縮醛的形成消除了這個(gè)問題。CatalytichydrogenolysisofanO-benzylprotectivegroupisamild,selectivemethodintroducedbyBergmannandZervastocleaveabenzylcarbamatepreparedtoprotectanaminogroupduringpeptidesyntheses、[haidr?ud??‘n?l?sis]氫解作用、破壞加氫(作用)、[?benzil]鄰苯甲基、[‘kɑ:b??meit]氨基甲酸鹽、[?peptaid]肽、縮氨酸鄰苯甲基保護(hù)基的催化氫解作用是Bergmann和Zervas引入的一種在制備肽的過程中,分解所制備的苯甲基氨基甲酸鹽來保護(hù)氨基基團(tuán)的溫和的和選擇性的方法。Themethodalsohasbeenusedtocleavealkylbenzylethers,stablepoundspreparedtoprotectalkylalcohols;benzyl[?benzil]鄰苯甲基ether[?i:θ?(r)]醚這種方法也差不多用來分解所制備的穩(wěn)定的化合物烷基苯甲基醚來保護(hù)烷基醇。benzylestersarecleavedbycatalytichydrogenolysisunderneutralconditions、ester[?est?(r)]酯catalytic[?k?t?'litik]催化劑、起催化作用的hydrogenolysis[haidr?ud??'n?l?sis]氫解作用、破壞加氫(作用)neutral[?nju:tr?l]中性的苯甲基醚在中性條件下被催化氫解作用所分解。

Threeselectivemethodstoremoveprotectivegroupsarereceivingmuchattention:“assisted,”electrolytic,andphotolyticremoval、electrolytic[i?lektr?'litik]電解的、電解質(zhì)、photolytic[f?ut?'litik]光解的、removal[ri'mu:vl]免職、除去、移走、搬遷有三種除去保護(hù)基的選擇性方法引起了關(guān)注:“assisted,”電解消除法,光解消除法。Fourexamplesillustrate“assistedremoval”ofaprotectivegroup、illustrate['il?streit]說明、表明、給…加插圖、(用示例、圖畫等)說明removal[ri'mu:vl]免職、除去、移走、搬遷有四個(gè)例子證明了保護(hù)基的輔助性消除。Astableallylgroupcanbeconvertedtoalabilevinylethergroup(eq、4);allyl['?l?l]烯丙基labile['leibail]不安定的、易發(fā)生變化的vinyl['vainl]乙烯基ether[?i:θ?(r)]醚一個(gè)穩(wěn)定的烯丙基能夠轉(zhuǎn)變成不穩(wěn)定的乙烯基醚(方程式4)。aβ-haloethoxy(eq、5)orβ-silylethoxy(eq、6)derivativeiscleavedbyattackattheβ-substituent;haloethoxy['h?l?u'iθ?ksi]鹵代乙氧基silylethoxy['silil'iθ?ksi]甲硅烷基乙氧基derivative[di?riv?tiv]衍生的、衍生物β-鹵代乙氧基(方程式5)或β-甲硅烷基乙氧基(方程式6)的衍生物因?yàn)棣氯〈贿M(jìn)攻而分解。andastableo-nitrophenylderivativecanbereducedtotheo-aminopound,whichundergoescleavagebynucleophilicdisplacement:nitrophenyl[‘naitr?fenil]硝基苯基、derivative[di?riv?tiv]衍生物、amino[?'mi?n?u]氨基的nucleophilic[nju:kli?u'filik]親核的、親質(zhì)子的一個(gè)穩(wěn)定的鄰硝基苯基衍生物能夠被還原成在親核取代反應(yīng)的作用下而分解的鄰氨基化合物。Thedesignofnewprotectivegroupsthatarecleavedby“assistedremoval”isachallengingandrewardingundertaking、removal[ri'mu:vl]免職、除去、challenging[?t??lind?i?]挑戰(zhàn)性的、rewarding[ri?w?:di?]報(bào)答的、有益的、undertaking[??nd??teiki?]事業(yè)、工作因“assistedremoval”而分解的新的保護(hù)基的設(shè)計(jì)是一項(xiàng)挑戰(zhàn)性和值得一做的事業(yè)(充滿了挑戰(zhàn)和機(jī)遇的工作)。Removalofaprotectivegroupbyelectrolyticoxidationorreductioncanbeverysatisfactory、removal[ri'mu:vl]免職、除去、移走、搬遷electrolytic[i?lektr?‘litik]電解的、由電解產(chǎn)生的、電解質(zhì)、satisfactory[?s?tis?f?kt?ri]令人滿意的、符合要求的用電解氧化或還原除去保護(hù)基是特別令人滿意的。Theequipmentrequiredrangesfromaminimumoftwoelectrodes,apotentiostat,andasourceofDCcurrenttoquitesophisticatedsystems、electrode[i?lek?tr?ud]電極、potentiostat[p?‘ten?i?st?t]穩(wěn)壓器、sophisticated[s??fistikeitid]高度發(fā)展的、周密復(fù)雜的所需要的設(shè)備從最低限度的兩個(gè)電極,穩(wěn)壓器和直流電源到到特別周密復(fù)雜的系統(tǒng)。Asuitableelectrolyte/solventsystemisneeded,andthedeprotectedproductmustnotundergofurtherelectrochemistryundertheexperimentalconditions、electrolyte[i?lektr??lait]電解、電解液、solvent[?s?lv?nt]溶劑、electrochemistry[i?lektr?u‘kemistri]電化學(xué)同時(shí)需要合適的電解液/溶劑系統(tǒng),而且去質(zhì)子化的產(chǎn)物在實(shí)驗(yàn)條件下必須不能發(fā)生進(jìn)一步的電化學(xué)反應(yīng)。Theuseandsubsequentremovalofchemicaloxidantsorreductants(e、g、,CrorPbsalts;Pt-CorPd-C)areeliminated、subsequent[?s?bsikw?nt]后來的、隨后的、eliminate[i‘limineit]排除、消除、Cr、chromium[?kr?umi?m]、Pb、plumbum[’pl?mb?m]、Pt、platinum['pl?tin?m]化學(xué)氧化劑或還原劑(例如Cr或Pbsalts;Pt-C或Pd-C)的使用和隨后的去除被消除。Reductivecleavageshavebeencarriedoutinhighyieldat-1to-3V(vs、SCE)dependingonthegroup;volt[v?ult]還原分解差不多在-1到-3V范圍內(nèi)依賴于基團(tuán)以高產(chǎn)率進(jìn)行。Oxidativecleavagesingoodyieldhavebeenrealizedat1、5-2V(vs、SCE)、在1、5-2V的氧化分解也差不多以高產(chǎn)率實(shí)現(xiàn)。Forsystemspossessingtwoormoreelectrochemicallylabileprotectivegroups,selectivecleavageispossiblewhenthehalfwavepotentials,E1-2,aresufficientlydifferent;electrochemically[i?lektr?u‘kemik?li]電氣化學(xué)地、labile[‘leibail]不穩(wěn)定的、易變化的、易分解的、potential[p??ten?l]潛在的、有估計(jì)的、sufficiently[s?’fi?ntli]足夠地、充分地關(guān)于擁有兩個(gè)或更多電化學(xué)上不穩(wěn)定的保護(hù)基來說,當(dāng)半波電位E1-2差異較大時(shí),估計(jì)發(fā)生選擇性分解。excellentselectivitycanbeobtainedwithpotentialdifferencesontheorderof(屬于…一類的,與…相似的)0、25V、excellent[?eks?l?nt]potential[p??ten?l]潛在的、有估計(jì)的volt[v?ult]在電勢(shì)差接近0、25V時(shí),能夠得到良好的選擇性分解。Protectivegroupsthathavebeenremovedbyelectrolyticoxidationorreductionaredescribedattheappropriateplacesinthisbook;electrolytic[i?lektr?u?litik]電解的、由電解產(chǎn)生的、電解質(zhì)、appropriate[??pr?upriit]適當(dāng)?shù)?、恰?dāng)?shù)?、合適的這本書在合適(一定)的位置對(duì)用電解氧化或電解還原能夠去除的保護(hù)基進(jìn)行了介紹。areviewarticlebyMairanovskydiscusseselectrochemicalremovalofprotectivegroups、Mairanovsky所寫的一篇綜述性文章保護(hù)基的電化學(xué)去除方法。Photolyticcleavagereactions(e、g、,ofo-nitrobenzyl,phenacyl,andnitrophenyl-sulfenylderivatives)takeplaceinhighyieldonirradiationoftheprotectedpoundforafewhoursat254～350nm、electrolytic[i?lektr?u?litik]電解的、phenacyl[‘fen?sil]苯甲酰甲基、sulfenyl[s?l’fenil]氧硫基irradiation[i?reidi‘ei?n]放射、照射在254-350nm范圍對(duì)所保護(hù)的化合物進(jìn)行輻射,光分解作用(例如:鄰硝基苯甲基、苯甲酰甲基、硝基苯基亞磺?；难苌锏墓饨庾饔?能夠以高產(chǎn)率發(fā)生。Forexample,theo-nitrobenzylgroup,usedtoprotectalcohols,amines,andcarboxylicacids,hasbeenremovedbyirradiation、amine[?‘mi:n]胺、carboxylic[kɑ:b?k’silik]羧基的、irradiation[i?reidi'ei?n]放射、照射、光滲例如,用來保護(hù)醇、胺和羧酸的鄰硝基苯甲基能夠利用輻射去除。Protectivegroupsthathavebeenremovedbyphotolysisaredescribedattheappropriateplacesinthisbook;photolysis[f?u't?lisis]光分解、光解作用appropriate[??pr?upriit]適當(dāng)?shù)?、合適的差不多用光解作用去除的保護(hù)基將在這本書的適當(dāng)?shù)牡胤竭M(jìn)行介紹。inaddition,thereadermaywishtoconsultthreereviewarticles、另外,讀者估計(jì)希望參考三篇綜述。Toselectaspecificprotectivegroup,thechemistmustconsiderindetailallthereactants,reactionconditions,andfunctionalitiesinvolvedintheproposedsyntheticscheme、從這本書中選擇保護(hù)基為了選擇特效的保護(hù)基,化學(xué)家必須對(duì)所提出的合成系統(tǒng)中涉及到的所有反應(yīng)物,反應(yīng)條件以及功能進(jìn)行詳細(xì)的考慮。4、SelectionofaProtectiveGroupfromThisBookFirstheorshemustevaluateallfunctionalgroupsinthereactanttodeterminethosethatwillbeunstabletothedesiredreactionconditionsandrequireprotection、evaluate[i'v?ljueit]評(píng)價(jià)首先,他或她必須對(duì)反應(yīng)物的所有功能基團(tuán)進(jìn)行評(píng)價(jià),來決定哪些基團(tuán)關(guān)于所期望的反應(yīng)條件不穩(wěn)定和需要保護(hù)。Thechemistshouldthenexamine[iɡ?z?min]reactivitiesofpossibleprotectivegroups,listedintheReactivityCharts(圖表),todeterminepatibility([k?m?p?t??bil?ti]、兼容性)ofprotectivegroupandreactionconditions、然后,化學(xué)家應(yīng)該對(duì)列在反應(yīng)圖中的估計(jì)的保護(hù)基進(jìn)行檢測(cè)來確定保護(hù)基和反應(yīng)條件的兼容性。TheprotectivegroupslistedintheReactivityChartshavebeenusedmostwidely;consequently[?k?nsikw?ntli],considerable[k?n?sid?r?bl]experimentalinformationisavailableforthem、列在反應(yīng)圖中的保護(hù)基差不多得到了最廣泛的使用,因此化學(xué)家就能夠獲得大量的實(shí)驗(yàn)信息。Heorsheshouldconsulttheplete[k?m?pli:t]listofprotectivegroupsintherelevantchapterandconsidertheirproperties、他或她必須對(duì)在相關(guān)章節(jié)中列出保護(hù)基的整個(gè)表格進(jìn)行考慮,考慮它們的性質(zhì)。Itwillfrequently(往往)beadvisable[?d?vaiz?bl]toexaminetheuseofoneprotectivegroupforseveralfunctionalgroups、檢測(cè)具有幾種功能的一個(gè)保護(hù)基的用途往往是明智的。(i、e、,a2,2,2-trichloroethylgrouptoprotectahydroxylgroupasanether[?i:θ?],acarboxylic[kɑ:b?k'silik]acidasanester[?est?],andanamino[??mi:n?u]groupasacarbamate[?kɑ:b?meit]、)(也就是2,2,2-三氯乙基能夠作為醚來保護(hù)羥基,作為酯來保護(hù)羧基,作為氨基甲酸鹽來保護(hù)氨基)。Whenseveralprotectivegroupsaretoberemovedsimultaneously([saim?l?teini?sli]、同時(shí)地),itmaybeadvantageous[??dv?n?teid??s]tousethesameprotectivegrouptoprotectdifferentfunctionalgroups、當(dāng)幾個(gè)保護(hù)基要同時(shí)去除時(shí),用同一個(gè)保護(hù)基來保護(hù)不同的基團(tuán)是有利的(方便的)。(e、g、,benzylgroup,removedbyhydrogenolysis,toprotectanalcoholandacarboxylicacid)、hydrogenolysis[haidr?ud??'n?l?sis]氫解作用、破壞加氫(作用)(例如,用能夠由氫解作用去除的苯甲基來保護(hù)醇和羧酸)。Whenselectiveremovalisrequired,differentclassesofprotectionmustbeused、當(dāng)需要選擇性去除時(shí),必須使用不同種類的保護(hù)。(e、g、,abe