PIPERAZINO-FUNCTIONALIZED SILICA-GEL AS A DEBLOCKING-SCAVENGING AGENT FOR THE 9-FLUORENYLMETHYLOXYCARBONYL AMINO-PROTECTING GROUP
PIPERAZINO-FUNCTIONALIZED SILICA-GEL AS A DEBLOCKING-SCAVENGING AGENT FOR THE 9-FLUORENYLMETHYLOXYCARBONYL AMINO-PROTECTING GROUP
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DOI：
10.1021/jo00153a009
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发表时间：
1983-01-01
影响因子：
3.6
通讯作者：
KNAPCZYK, J
中科院分区：
文献类型：
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作者：
CARPINO, LA;MANSOUR, EME;KNAPCZYK, J
将环状仲胺残基键合到硅胶表面上，得到了能够将9-芴基甲氧羰基氨基保护基解封闭并同时清除在解封闭过程中释放的二苯并富烯（DBF）的不溶性试剂。通过使三甲氧基硅烷5与色谱级二氧化硅反应，最容易制备具有约1.1毫当量NH/g的哌嗪二氧化硅试剂6。使用后，用过的试剂可以通过用过量哌啶处理来再生。以类似方式制备三聚氰胺二氧化硅14和15。对于氨基官能化硅橡胶和各种简单的环状仲胺（哌嗪、哌啶等），DBF（2）和加合物7之间存在平衡（方程式3），平衡位置取决于胺、溶剂等的性质。在Me 2SO中解封闭和达到平衡都比在氯仿或二氯甲烷中快。在Me 2SO中，通过从反应介质中沉淀加合物，平衡移向完全清除。先前1，我们表明具有通式1的环状仲氨基官能团的交联聚苯乙烯引起9-芴基甲氧羰基（Fmoc）氨基保护基2的解封闭，释放二苯并富烯（DBF）。2，其随后被相同的不溶性试剂清除，得到加合物3（当量1）。过滤并蒸发溶剂，然后
Bonding cyclic secondary amino residues to the surface of silica gel has giveninsoluble reagents capable of deblocking the 9-fluorenylmethyloxycarbonyl amino-protecting group and at the same time scavenging the dibenzofulvene (DBF) liberated in the deblocking process. A piperazine silica reagent 6 bearing approximately 1.1 mequiv of NH/g was easiest to prepare by reaction of trimethoxysilane 5 with chromatographic-grade silica. After use, spent reagent could be regenerated by treatment with excess piperidine. Piperidine silicas 14 and 15 were made similarly. For the amino-functionalized silicareagents and a variety of simple cyclicsecondary amines (piperazine, piperidine, etc.) the existence of an equilibrium (eq 3) between DBF (2) and adduct 7 has been established with the position of equilibrium being dependent on the nature of the amine, solvent, etc. Both deblocking and attainment of equilibrium were faster in Me2SO than in chloroform or dichloromethane. With piperazines in Me2SO the equilibrium was shifted toward completescavenging by precipitation of the adduct from the reaction medium.Previously1 we showed that cross-linked polystyrenes bearing cyclic secondary amino functions of general structure 1 caused deblocking of the 9-fluorenylmethyloxycarbonyl (Fmoc) amino-protecting group2 with the liberation of dibenzofulvene (DBF) 2 which is subsequently scavenged by the same insoluble reagent togive adduct 3 (eq 1). Filtration and evaporation of the solvent then