The protection of arginine (Arg) side chains is a crucial issue in peptide chemistry because of the propensity of the basic guanidinium group to produce side reactions. Currently, sulfonyl-type protecting groups, such as 2,2,5,7,8-pentamethylchroman (Pmc) and 2,2,4,6,7-pentamethyldihydrobenzofurane (Pbf), are the most widely used for this purpose. Nevertheless, Arg side chain protection remains problematic as a result of the acid stability of these two compounds. This issue is even more relevant in Arg-rich sequences, acid-sensitive peptides and large-scale syntheses. The 1,2-dimethylindole-3-sulfonyl (MIS) group is more acid-labile than Pmc and Pbf and can therefore be a better option for Arg side chain protection. In addition, MIS is compatible with tryptophan-containing peptides.
精
氨酸(Arg)侧链的保护是肽
化学中的一个关键问题,因为碱性
胍基容易产生副反应。目前,磺酰类保护基团,如
2,2,5,7,8-五甲基色满(Pmc)和 2,2,4,6,7-五甲基二氢
苯并呋喃(Pbf),在这方面的应用最为广泛。然而,由于这两种化合物的酸稳定性,Arg 侧链保护仍然存在问题。对于富含 Arg 的序列、对酸敏感的肽和大规模合成来说,这个问题更加重要。与 Pmc 和 Pbf 相比,
1,2-二甲基吲哚-3-磺酰基(MIS)更耐酸,因此是保护 Arg 侧链的更好选择。此外,MIS 与含色
氨酸的肽兼容。