手性布朗斯特酸催化环己酮的不对称胺化反应研究
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摘要
近些年来手性布朗斯特酸催化剂得到蓬勃发展，这类催化剂一般具有对水和氧气稳定，便于保存和易于操作的优势，因而成为了有机小分子催化剂中倍受关注的研究领域。在众多手性布朗斯特酸中，手性联二萘酚磷酸类催化剂成为一类极具吸引力、应用范围广的新兴催化剂。
在催化反应中，合成具有立体选择性的C-N键有着很重要的意义，含有此结构的分子在许多重要化合物中起着关键的手性作用。例如，α-氨基羰基化合物可以制备天然和非天然氨基酸、氨基醇。在手性碳原子与氮原子成键方法中，氮源直接不对称加成在手性碳中心上是较为简单有效的。本论文使用新型手性布朗斯特酸：联二萘酚磷酰亚胺催化剂BPI为催化剂，以偶氮类化合物为氮源，以环己酮的羰基α-碳为手性中心，催化不对称胺化反应，形成了具有立体选择性的C-N键。具体工作如下：
首先，设计并合成了新型的手性联二萘酚磷酰亚胺催化剂BPI，特点是磷酰胺的氮原子上首次引入了带有第二个手性联二萘酚骨架的磷酰基，形成一类新颖的具有双C2对称轴的磷酰亚胺类催化剂。通过引入空间位阻和电子效应不同的3,3′位取代基，催化剂BPI可以进行有效的调控，进而实现催化剂的催化性能微调，应用于环己酮的胺化反应。
其次，以环己酮与偶氮二甲酸二异丙酯的胺化反应为模板，筛选了5类共10种手性催化剂，包括：1种手性联二萘酚催化剂、2种手性磷酸类催化剂、1种手性磷酰亚胺类催化剂、4种手性伯胺类催化剂和2种手性硫脲类催化剂。在饱和食盐水为溶剂时，对比其他四类催化剂，新型的手性磷酰亚胺类催化剂BPI首次实现了催化环己酮的不对称胺化反应，并且表现出优异的催化活性，得到了93%ee值的胺化产物。
最后，以环己酮与偶氮二甲酸二异丙酯的胺化反应为模板，使用5种手性磷酰亚胺催化剂，分别考察了油浴加热与微波加热下的溶剂、催化剂和温度对产物的收率和对映选择性影响。在油浴加热时，氯仿为溶剂，催化剂为BPI3，反应时间为96小时，50℃、10mol%的催化剂下，得到收率25%、ee值96%的胺化产物。在微波加热时，1,2-二氯乙烷为溶剂，催化剂为BPI3，反应时间为90分钟，10mol%的催化剂下，得到了收率85%、ee值98%的胺化产物。通过实验结果对比，微波加热的应用使反应时间由96小时缩短为90分钟，收率由25%提高至85%，ee值由96%提高至98%。微波加热成功地促进胺化反应的进行，不仅能够有效地缩短反应时间，而且提高了胺化产物的对映选择性和收率。
通过本论文的研究，为以后催化环己酮的不对称胺化反应提供了丰富的实验数据和实验经验。
Chiral Br nsted acid catalysts have been booming in recent years.In the presence ofwater and oxygen, the catalysts can effectively maintain the catalytic activity,so that theycan be saved and operated easily. And chemists are very concerned about chiral Br nstedacid catalysts. In the number of chiral Br nsted acid, the chiral binaphthol phosphatecatalysts become an attractive emerging catalyst with wide range of applications.
It is significant to synthesize stereoselective compounds with C-N bond from avail-able starting materials in organic chemistry, and molecules with C-N bond play the keychiral role in many important compounds. As we all know, it is simple and effective fordirectly asymmetric addition of the chiral carbon center to the nitrogen in many ways ofbonding method by chiral carbon atoms and nitrogen atoms. In this thesis the catalyticenantioselective amination reactions of cyclic ketones using azodicarboxylates as thenitrogen source with BPI as the catalyst are presented,and this thesis involves thefollowing parts:
First of all, we designed and synthesized chiral BINOL-derived Phosphorus imideBPI, which was first introduced with the second chiral binaphthol phosphoryl. The novelphosphorus imides catalyst has a dual-axis of symmetry.By the introduction of the stericand electronic effects at3,3'substituent, BPI can be controled effectively,and be appliedto amination reaction.
Secondly, we made asymmetric amination of cyclic ketones as a template to studythe five different types of catalyst, including BINOL, chiral BINOL-derived phosphoricacids, catalyst BPI, chiral primary amine cataysts,and hiourea. According to the results,we found that there was a excellent catalytic properties catalyst BPI,and the productgained93%ee.
Finally,we documented the asymmetric amination of cyclohexanone with the use ofcatalyst BPI.The influence of solvents,catalyst and temperature to the yields and enantio-selectivities of the adducts was investigated, and a series of encouraging results wereobserved.Heated in the oil bath,the product gained25%yield and96%ee value,while heated in the microwave, the product gained85%the yield and98%ee value at theoptimized conditions.By comparison of experimental results,the reaction time shortenedfrom96hours to90minutes,the yield increased from25%to85%and ee value increasedfrom96%to98%by the application of microwave heating. Microwave heating not onlycan effectively shorten the reaction time, and improve the enantioselectivity and yield ofamination product.
Our research provided preliminary results to our work on the asymmetric aminationof cyclic ketones and further studied is currently underway.
在催化反应中，合成具有立体选择性的C-N键有着很重要的意义，含有此结构的分子在许多重要化合物中起着关键的手性作用。例如，α-氨基羰基化合物可以制备天然和非天然氨基酸、氨基醇。在手性碳原子与氮原子成键方法中，氮源直接不对称加成在手性碳中心上是较为简单有效的。本论文使用新型手性布朗斯特酸：联二萘酚磷酰亚胺催化剂BPI为催化剂，以偶氮类化合物为氮源，以环己酮的羰基α-碳为手性中心，催化不对称胺化反应，形成了具有立体选择性的C-N键。具体工作如下：
首先，设计并合成了新型的手性联二萘酚磷酰亚胺催化剂BPI，特点是磷酰胺的氮原子上首次引入了带有第二个手性联二萘酚骨架的磷酰基，形成一类新颖的具有双C2对称轴的磷酰亚胺类催化剂。通过引入空间位阻和电子效应不同的3,3′位取代基，催化剂BPI可以进行有效的调控，进而实现催化剂的催化性能微调，应用于环己酮的胺化反应。
其次，以环己酮与偶氮二甲酸二异丙酯的胺化反应为模板，筛选了5类共10种手性催化剂，包括：1种手性联二萘酚催化剂、2种手性磷酸类催化剂、1种手性磷酰亚胺类催化剂、4种手性伯胺类催化剂和2种手性硫脲类催化剂。在饱和食盐水为溶剂时，对比其他四类催化剂，新型的手性磷酰亚胺类催化剂BPI首次实现了催化环己酮的不对称胺化反应，并且表现出优异的催化活性，得到了93%ee值的胺化产物。
最后，以环己酮与偶氮二甲酸二异丙酯的胺化反应为模板，使用5种手性磷酰亚胺催化剂，分别考察了油浴加热与微波加热下的溶剂、催化剂和温度对产物的收率和对映选择性影响。在油浴加热时，氯仿为溶剂，催化剂为BPI3，反应时间为96小时，50℃、10mol%的催化剂下，得到收率25%、ee值96%的胺化产物。在微波加热时，1,2-二氯乙烷为溶剂，催化剂为BPI3，反应时间为90分钟，10mol%的催化剂下，得到了收率85%、ee值98%的胺化产物。通过实验结果对比，微波加热的应用使反应时间由96小时缩短为90分钟，收率由25%提高至85%，ee值由96%提高至98%。微波加热成功地促进胺化反应的进行，不仅能够有效地缩短反应时间，而且提高了胺化产物的对映选择性和收率。
通过本论文的研究，为以后催化环己酮的不对称胺化反应提供了丰富的实验数据和实验经验。
Chiral Br nsted acid catalysts have been booming in recent years.In the presence ofwater and oxygen, the catalysts can effectively maintain the catalytic activity,so that theycan be saved and operated easily. And chemists are very concerned about chiral Br nstedacid catalysts. In the number of chiral Br nsted acid, the chiral binaphthol phosphatecatalysts become an attractive emerging catalyst with wide range of applications.
It is significant to synthesize stereoselective compounds with C-N bond from avail-able starting materials in organic chemistry, and molecules with C-N bond play the keychiral role in many important compounds. As we all know, it is simple and effective fordirectly asymmetric addition of the chiral carbon center to the nitrogen in many ways ofbonding method by chiral carbon atoms and nitrogen atoms. In this thesis the catalyticenantioselective amination reactions of cyclic ketones using azodicarboxylates as thenitrogen source with BPI as the catalyst are presented,and this thesis involves thefollowing parts:
First of all, we designed and synthesized chiral BINOL-derived Phosphorus imideBPI, which was first introduced with the second chiral binaphthol phosphoryl. The novelphosphorus imides catalyst has a dual-axis of symmetry.By the introduction of the stericand electronic effects at3,3'substituent, BPI can be controled effectively,and be appliedto amination reaction.
Secondly, we made asymmetric amination of cyclic ketones as a template to studythe five different types of catalyst, including BINOL, chiral BINOL-derived phosphoricacids, catalyst BPI, chiral primary amine cataysts,and hiourea. According to the results,we found that there was a excellent catalytic properties catalyst BPI,and the productgained93%ee.
Finally,we documented the asymmetric amination of cyclohexanone with the use ofcatalyst BPI.The influence of solvents,catalyst and temperature to the yields and enantio-selectivities of the adducts was investigated, and a series of encouraging results wereobserved.Heated in the oil bath,the product gained25%yield and96%ee value,while heated in the microwave, the product gained85%the yield and98%ee value at theoptimized conditions.By comparison of experimental results,the reaction time shortenedfrom96hours to90minutes,the yield increased from25%to85%and ee value increasedfrom96%to98%by the application of microwave heating. Microwave heating not onlycan effectively shorten the reaction time, and improve the enantioselectivity and yield ofamination product.
Our research provided preliminary results to our work on the asymmetric aminationof cyclic ketones and further studied is currently underway.
引文
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[78]Lidstrom, P.; Tierney, J.; Wathey, B.; Westman, J., Tetrahedron.2001,57,922
[79]Loupy, A.,“Microwaves in organic synthesis”,Wiley, Weinheim,2002
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[81]Kappe, C. O.; Stadler, A.,“Microwaves in organic and medicinal chemistry”, Wiley,Weinheim,2005
[82]Kuznetsov, D. V.; Raev, V. A.; Kuranov, G. L.; Arapov, O. V.; Kostikov, R. R., Russ.J. Org. Chem.2005,41,1719
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[87]Gronnow, M. L.; White,R. J.; Clark, J. H.; Macquarrie, D,.J. Org. Process Res. Dev.2005,9,516
[88]Lidstrom, P.; Tierney, J.; Wathey, B.; Westman, J.,“Microwave Assisted OrganicSynthesis-A Review”, Tetrahedron,2001,57,9225-9283.
[89]Larhed, M.; Hallberg, A.,“Microwave-Assisted High-Speed Chemistry: A NewTechnique in Drug Discovery”,Drug Discovery Today2001,6,406-416.