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1、1,Oxidation reaction in organic synthesis,Wang Jinliang01/13/2011,2,Outline,Introduction氧化反应-定义氧化反应的分类氧化剂种类经典反应举例Questions,3,The utility of oxidation in organic synthesis:胡跃飞，林国强现在有机反应(第一卷：氧化反应)Chem.Rev.2006,106,2943-2989 Large-Scale Oxidations in the Pharmaceutical Industry,一.Introduction：,4,2.氟轻松,
2、5,2.氧化反应定义,狭义的氧化：物质与氧化合，加氧去氢；氧化时氧化值升高；氧化也称氧化作用或氧化反应。有机物反应时把有机物引入氧或脱去氢的作用叫氧化；广义的氧化：物质发生了电子转移，使C上电子云密度降低。氧化反应:物质失电子的作用叫氧化反应；得电子的作用叫还原。,6,2.氧化反应定义,按照这样的定义，下列强亲电性试剂是适宜的氧化剂：其中有：硝酸、氧、过氧化物（过氧化氢、金属过氧化物、无机和有机过氧酸)硫，二氧化硒、氯、溴、次卤酸。过碘酸、高价金属化物（铁和钛/四氧化锇、四氧化钌、二氧化锰、高锰酸钾、铬酸及铬酐、二氧化铅和四醋酸铅）。化合物被氧化的容易程度随亲核性的增强而增加，大致顺序：,另外
3、，一个有机化合物的可氧化性一般与其可被利用的氢原子有关，氧化伴随着氢的给出或者氧的获得。例如甲苯可被氧化为苯甲醛，进一步氧化为苯甲酸。,7,3.氧化反应的分类,8,1.Transition metal drivativesCr,Mn等。PCC(Coreys Reagent CrO3+Pyridine+HCl),PDC(Pyridinium dichromate CrO3+H2O+Pyridine),2.Oxygen,Ozone and peroxides non-metalic oxidantsO2,O3,RCOOOH,H2O2,t-BuOOH3.other reagentsSome Stro
4、ngly electrophilic reagents,etc.,etc.,4.Oxidants,9,5.经典反应举例,1.Swern Oxidation：,General features of Swern Oxidation1.DMSO can also be activated by other reagents such as TFAA,SO3/Py,(AcO)2O and P2O5;2.When(COCl)2 is used,the initial intermediate is unstable above-60 0C for benzyl or allylic alcohols,
5、or above-20 0C for other alcohols3.Yield of Swern Oxidation is high.However,the condition can cause epimerization of alfa-chiral center and C=C migration and was not good in too small(mg)or too large scale(Kg).4.位阻大的2o羟基反应活性降低较多,10,Mechanism:,11,Swern Oxidation examples：,12,2.KMnO4：,KMnO4氧化的特点：强氧化性氧
6、化产物与体系的PH密切相关，酸性条件下氧化性更强，KMnO4的副产物也与PH关系很大。,13,14,3.MnO2：,General features of Swern Oxidation Used in oxidizing benzyl or allylic alcohols;2.MnO2 can be re-activated at 110-130 0C for 3-4 h before used(Infra-red oven);3.The reaction was carried out at room temperature,excess(10 eq)MnO2 needed to get
7、 to completion.,MnO2 example：,15,4.Dess-Martin 氧化,Mechanism of Dess-Martin oxidation：,16,Preparation of IBX and DMP,17,General features of Dess-Martin Oxidation：1.Mild reaction conditions(room temperature,neutral pH);selectively oxidizing alcohol.2.IBX can oxidizing 1and 2alcohol to carboxyl product
8、 in DMSO under mild conditions.3.Configuration of conjugating C=C remained4.DMP is especially good for Fluo-containing compounds,Dess Martin examples：,Synlett.2001,1974-1976,J.Org.Chem.1989,54,661-668,18,5.Good ee retention of near chiral center,Swern:81%ee;Tempo:90%ee;DMP:96%eeTetrahedron lett.2000
9、,41,1359-1362,19,5.TEMPO Oxidation:,Mechanism of tempo oxidation：,20,General features of Tempo Oxidation：1.The oxidation is cheap,mild and can be carried out in small and large scales 2.Selectively oxidizing primary alcohols.3.Alcohols can be converted to aldehydes or acids at different conditions(p
10、H,oxidants).,Tempo oxidation example：,J.Org.Chem.1999,64,2564-2566,21,6.Sharpless epoxidation：,General features of tempo Oxidation：1.简易；2.可靠，对于大多数烯丙醇反应都能成功，3.高光学选择性，一般90%de;4.产物的绝对构型可以预见，迄今对于图示的规律尚没见反例报道。5.产物作为中间体的多用性.,反应机理:略Ti-酒石酸酯配合物,22,Sharpless epoxidation examples：,雌舞毒蛾引诱剂,23,6.Questions,24,25,Thanks!The end!,
