硅胶负载三氟甲烷磺酸在碳水化合物合成化学中的应用研究
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摘要
强酸性催化剂在现代有机合成化学尤其是工业生产中有着十分广泛的应用，但是由于它们自身固有的强酸性以及强腐蚀性，使得它们在储存、使用以及后处理过程中均存在一定风险，因而给人们的使用尤其是工业生产带来诸多不便。伴随着当今“绿色化学”发展要求以及社会可持续发展需要，人们将其负载于固体无机载体制成相应的固体负载酸能够有效地解决以上弊端。最近十多年来，固体负载酸在有机合成化学中的应用研究开展的如火如荼，但其在碳水化合物合成化学中的应用研究相对滞后。本文首次将硅胶负载三氟甲烷磺酸应用于糖水化合物的合成研究，着重研究了它在羟基保护、羟基脱保护、官能团转化以及糖苷化方面的应用。本论文主要包括以下三个方面的工作：
一、硅胶负载三氟甲烷磺酸选择性脱除叔丁基二苯基硅基方法学研究
本文报道了一种快速、高效、化学选择性的脱除叔丁基二苯基硅基的新方法。50℃下，以乙腈为反应溶剂，10mol%TfOH-SiO2为催化剂，糖类、甾体、烷基以及芳基衍生物中的叔丁基二苯基硅基可被化学选择性脱除以非常理想的收率得到其相应的母体化合物。
二、硅胶负载三氟甲烷磺酸催化碳水化合物邻二醇选择性保护方法学研究及其在天然产物全合成中的应用
1：室温条件下，以无水丙酮为溶剂、2,2-二甲氧基丙烷为异丙叉基化试剂、5mol%TfOH-SiO2为催化剂可以快速、高效、化学选择性的异丙叉基化保护“裸露”单糖或部分保护单糖及双糖衍生物1,2-二醇或1,3-二醇。
2：室温条件下，以无水乙腈为溶剂、苯甲醛二甲醚为苄叉基化试剂、5mol%TfOH-SiO2为催化剂可以快速、高效、化学选择性的苄叉基化保护部分保护单糖衍生物的1,3-二醇。
3：利用硅胶负载三氟甲烷磺酸作为催化剂制备得到的相应单糖异丙叉基化或苄叉基化产物为基本反应砌块，NIS/TfOH-SiO2催化硫苷供体糖苷化，我们成功合成了从Salmonella enterica O59中分离得到的O-抗原四糖重复单元的对甲氧基苯基苷类似物，为其进一步的相关生物学研究奠定了基础。
三、硅胶负载三氟甲烷磺酸催化O-苷制备S-苷方法学研究
本文报道了一种有效的催化氧苷键转化为硫苷键的新方法。加热回流条件下，以10mol%TfOH-SiO2为催化剂、1.2个当量的硫醇或硫酚作为亲核试剂、二氯甲烷为反应溶剂，可以高收率其得到相应的官能团转化产物；该催化体系底物适用范围广，端基由甲基、正辛基、正十二烷基、苄基、炔丙基以及对甲氧基苯基等封闭的糖类衍生物均可适用。
Strong acidic catalysts have been used widely in the modern organic synthesis,especially in the industrial manufacture. But due to their intrinsic strong acidity andcausticity, there are some potential risks in their storage, usage and disposal, and thissomewhat reduces their application especially in industry. Following the urgentdemand of green chemistry and social sustainable development, people prepare thesolid supported acids with the strong acids adsorbed on inorganic supports to avoidthe disadvantages. In recent years, solid supported acids have received considerableattentions in organic synthesis, but their application research in the syntheticcarbohydrate chemistry is relative slow. We study the application of silica gelsupported triflic acid in the synthetic carbohydrate chemistry in this thesis for the firsttime, mainly focused on the glycosylation, functional group transformation and thecarbohydrate hydroxyl group protection and deprotection.
1. Study on the deprotection of TBDPS ethers catalyzed by TfOH-SiO_2
A rapid, efficient, chemoselective and environment-friendly method for thedeprotection of tert-butyldiphenylsilyl ethers mediated by triflic acid supported onsilica gel is reported. A wide range of tert-butyldiphenylsilyl ethers derived fromcarbohydrate, saponin, alkyl and aryl residues can be smoothly cleaved in thepresence of various types of other protecting groups in good to excellent yields inacetonitrile at50℃.
2. Study on the protection of diols catalyzed by TfOH-SiO2and its application
to the synthesis of natural products
1) Triflic acid immobilized on silica gel has been identified as an excellentcatalyst for the chemoselective O-isopropylidenation of free sugars and functionalizedcarbohydrates with2,2-dimethoxylpropane in acetone at room temperature.
2) Silica gel supported triflic acid has been used as an remarkable catalyst for thechemoselective O-benzylidenation of functionalized carbohydrates with benzaldehydedimethylacetal in acetonitrile at room temperature.
3) A tetrasaccharide related to the repeating unit of the O-polysaccharide isolatedfrom Salmonella enterica O59is prepared by using NIS/TfOH-SiO2as glycosylationcatalyst and O-isopropylidenated and O-benzylidenated monosaccharide derivativeswhich are synthesized as described before as building blocks.
3. Study on the conversion of glycosides into their corresponding thioglycosidescatalyzed by TfOH-SiO_2
A new method for the conversion of glycosides into their correspondingthioglycosides mediated by triflic acid supported on silica gel is reported. Thethioglycosides can be obtained by treating a wide range of glycosides derived frommethyl, n-octyl, n-dodecyl, propargyl, and p-methoxyphenyl residues with1.2equiv. thiol in dichloromethane at reflux condition.
一、硅胶负载三氟甲烷磺酸选择性脱除叔丁基二苯基硅基方法学研究
本文报道了一种快速、高效、化学选择性的脱除叔丁基二苯基硅基的新方法。50℃下，以乙腈为反应溶剂，10mol%TfOH-SiO2为催化剂，糖类、甾体、烷基以及芳基衍生物中的叔丁基二苯基硅基可被化学选择性脱除以非常理想的收率得到其相应的母体化合物。
二、硅胶负载三氟甲烷磺酸催化碳水化合物邻二醇选择性保护方法学研究及其在天然产物全合成中的应用
1：室温条件下，以无水丙酮为溶剂、2,2-二甲氧基丙烷为异丙叉基化试剂、5mol%TfOH-SiO2为催化剂可以快速、高效、化学选择性的异丙叉基化保护“裸露”单糖或部分保护单糖及双糖衍生物1,2-二醇或1,3-二醇。
2：室温条件下，以无水乙腈为溶剂、苯甲醛二甲醚为苄叉基化试剂、5mol%TfOH-SiO2为催化剂可以快速、高效、化学选择性的苄叉基化保护部分保护单糖衍生物的1,3-二醇。
3：利用硅胶负载三氟甲烷磺酸作为催化剂制备得到的相应单糖异丙叉基化或苄叉基化产物为基本反应砌块，NIS/TfOH-SiO2催化硫苷供体糖苷化，我们成功合成了从Salmonella enterica O59中分离得到的O-抗原四糖重复单元的对甲氧基苯基苷类似物，为其进一步的相关生物学研究奠定了基础。
三、硅胶负载三氟甲烷磺酸催化O-苷制备S-苷方法学研究
本文报道了一种有效的催化氧苷键转化为硫苷键的新方法。加热回流条件下，以10mol%TfOH-SiO2为催化剂、1.2个当量的硫醇或硫酚作为亲核试剂、二氯甲烷为反应溶剂，可以高收率其得到相应的官能团转化产物；该催化体系底物适用范围广，端基由甲基、正辛基、正十二烷基、苄基、炔丙基以及对甲氧基苯基等封闭的糖类衍生物均可适用。
Strong acidic catalysts have been used widely in the modern organic synthesis,especially in the industrial manufacture. But due to their intrinsic strong acidity andcausticity, there are some potential risks in their storage, usage and disposal, and thissomewhat reduces their application especially in industry. Following the urgentdemand of green chemistry and social sustainable development, people prepare thesolid supported acids with the strong acids adsorbed on inorganic supports to avoidthe disadvantages. In recent years, solid supported acids have received considerableattentions in organic synthesis, but their application research in the syntheticcarbohydrate chemistry is relative slow. We study the application of silica gelsupported triflic acid in the synthetic carbohydrate chemistry in this thesis for the firsttime, mainly focused on the glycosylation, functional group transformation and thecarbohydrate hydroxyl group protection and deprotection.
1. Study on the deprotection of TBDPS ethers catalyzed by TfOH-SiO_2
A rapid, efficient, chemoselective and environment-friendly method for thedeprotection of tert-butyldiphenylsilyl ethers mediated by triflic acid supported onsilica gel is reported. A wide range of tert-butyldiphenylsilyl ethers derived fromcarbohydrate, saponin, alkyl and aryl residues can be smoothly cleaved in thepresence of various types of other protecting groups in good to excellent yields inacetonitrile at50℃.
2. Study on the protection of diols catalyzed by TfOH-SiO2and its application
to the synthesis of natural products
1) Triflic acid immobilized on silica gel has been identified as an excellentcatalyst for the chemoselective O-isopropylidenation of free sugars and functionalizedcarbohydrates with2,2-dimethoxylpropane in acetone at room temperature.
2) Silica gel supported triflic acid has been used as an remarkable catalyst for thechemoselective O-benzylidenation of functionalized carbohydrates with benzaldehydedimethylacetal in acetonitrile at room temperature.
3) A tetrasaccharide related to the repeating unit of the O-polysaccharide isolatedfrom Salmonella enterica O59is prepared by using NIS/TfOH-SiO2as glycosylationcatalyst and O-isopropylidenated and O-benzylidenated monosaccharide derivativeswhich are synthesized as described before as building blocks.
3. Study on the conversion of glycosides into their corresponding thioglycosidescatalyzed by TfOH-SiO_2
A new method for the conversion of glycosides into their correspondingthioglycosides mediated by triflic acid supported on silica gel is reported. Thethioglycosides can be obtained by treating a wide range of glycosides derived frommethyl, n-octyl, n-dodecyl, propargyl, and p-methoxyphenyl residues with1.2equiv. thiol in dichloromethane at reflux condition.
引文
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