4-(4,6-Di[2,2,2-trifluoroethoxy]-1,3,5-triazin-2-yl)-4-methylomorpholinium Tetrafluoroborate. Triazine-Based Coupling Reagents Designed for Coupling Sterically Hindered Substrates
作者:Konrad G. Jastrzabek、Ramon Subiros-Funosas、Fernando Albericio、Beata Kolesinska、Zbigniew J. Kaminski
DOI:10.1021/jo2002038
日期:2011.6.3
the leaving group permitting formation of the cyclic intermediate or cyclic transition state and the absence of strongly solvating solvents. It has to be considered as highly probable that the absence of strongly solvating milieu favors cyclic intermediates or the cyclic transition state. Arrangement of both components into the cyclic intermediate or cyclic transition state by accumulation of the geminal
制备了4-(4,6-二[2,2,2-三氟乙氧基] -1,3,5-三嗪-2-基)-4-甲基吗啉四氟硼酸酯(DFET / NMM / BF 4),并用作试剂用于耦合位阻基片。证实在DFET / NMM / BF 4与羧酸的反应中形成了适当的三嗪“超活性”酯。在Fmoc-RinkAmide-AM-PS树脂上合成Leu-脑啡肽五肽的方法中,通过系统修饰N-甲基或α,α-二取代残基的-Gly-Gly-片段,已研究了该试剂的效率。并与经典铵盐2-(1 H-苯并三唑-1-基)-1,1,3,3-四甲基溴化四氟硼酸盐(TBTU)。通过合成Aib–Aib(Aib:α-氨基异丁酸),MeVal-MeVal和MeLeu-MeLeu,对于DFET / NMM / BF 4,获得了脑啡肽类似物相当优越的性能。相对于TBTU而言,无论反应条件如何。对涉及三嗪试剂的偶联的分析表明,控制偶联受空间阻碍的底物的效率的因素是离