Effects of steric bulk and stereochemistry on the rates of diketopiperazine formation from N-aminoacyl-2,2-dimethylthiazolidine-4-carboxamides (Dmt dipeptide amides)—a model for a new prodrug linker system
作者:Ghadeer A.R.Y. Suaifan、Mary F. Mahon、Tawfiq Arafat、Michael D. Threadgill
DOI:10.1016/j.tet.2006.09.009
日期:2006.11
amine-containing drugs. Reaction rates were dependant on pH. In the l,R diastereomeric series, increasing steric bulk of the Aaa side-chain (Gly, Ala, Phe, Val) led to decrease in the reaction rate. However, in the l,S series, the greatest rate of reaction was observed for the most bulky amino-acid (Val), with t½=15 min at pH 8.0. The effects of steric bulk and stereochemistry are rationalised through conformational
通过内肽酶从前药中释放活性药物需要使用类似肽的自消灭性分子夹。从载体上切下后,该夹子必须塌陷并迅速释放药物。设计了一系列的氨酰基-5,5-二甲基硫代脯氨酸(Aaa-Dmt)N-(2-(4-硝基苯基)乙基)酰胺。Boc-1-氨基酰基氟与R -DmtOH偶合,得到Boc-1-Aaa- R -DmtOH,将其转化为Boc-1-Aaa- R -Dmt N-(2-(4-硝基苯基)乙基)酰胺。通过Boc-Aaa PFP酯与S -DmtOH的反应制备1,S非对映异构体系列。l-Aaa-Dmt N使-(2-(4-硝基苯基)乙基)酰胺在水性缓冲液中环化成二酮哌嗪(DKP),驱除2-(4-硝基苯基)乙胺作为含胺药物的模型。反应速率取决于pH。在I,R非对映体系列中,Aaa侧链(Gly,Ala,Phe,Val)的立体体积增加导致反应速率降低。然而,在I,S系列中,对于最大的氨基酸(Val)观察到最大的反应速率,在pH