Trifluoroacetyl as a protecting group for HYNIC: stability in the presence of electrophiles and application in the synthesis of 99mTc-radiolabelled peptides
作者:M. Bashir-Uddin Surfraz、Robert King、Stephen J. Mather、Stefano C.G. Biagini、Philip J. Blower
DOI:10.1016/j.tet.2010.01.038
日期:2010.3
TrifluoroacetylHYNIC-peptides have recently been shown to label directly with 99mTc as efficiently as their non-trifluoroacetylated analogs. In this work, the trifluoroacetyl (Tfa) moiety has been evaluated as a protecting group for HYNIC against reaction with strong electrophiles. Fmoc-(trifluoroacetylHYNIC)-lysine, the chosen model starting material, was found to be resistant against acetaldehyde
最近显示三氟乙酰基HYNIC肽与其非三氟乙酰基化类似物一样,可以有效地直接标记99m Tc。在这项工作中,三氟乙酰基(Tfa)部分已被评估为HYNIC防止与强亲电试剂反应的保护基。发现Fmoc-(三氟乙酰基HYNIC)-赖氨酸,选定的模型起始材料,在1摩尔当量和1000 M过量时分别对乙醛和氯甲酸苄酯具有抗性。相反,具有游离肼基的Fmoc-(HYNIC)-赖氨酸衍生物在与乙醛孵育1小时后被定量转化为相应的。还发现Fmoc-(三氟乙酰基HYNIC)-赖氨酸可在很宽的pH范围(3.6-10)范围内对乙醛挑战保持稳定。高效率与使用非三氟乙酰化类似物获得的不良放射标记产率(34%)相比,使用Fmoc-(三氟乙酰基HYNIC)-赖氨酸在乙醛存在下可实现99m Tc放射标记(99%)。这些发现牢固地确立了三氟乙酰基作为HYNIC的方便和有效的保护基,并且是目前可用的标记策略的有希望的替代方法。