Kinetic selectivity in the N-alkylation of 2-pyridyl porphyrins: a facile approach to the alphaalphabetabeta scaffold.
Kinetic selectivity in the N-alkylation of 2-pyridyl porphyrins: a facile approach to the alphaalphabetabeta scaffold.
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2-吡啶基卟啉 N-烷基化的动力学选择性：ααββ 支架的简便方法。
DOI：
10.1021/jo062017r
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Groves,JohnT
中科院分区：
文献类型：
--
作者：
Datta,Ankona;Quintavalla,SuzanneM;Groves,JohnT
用3种不同的α-溴乙酰胺对meso-四（2-吡啶基）卟啉（2-PyP）进行四-N-烷基化反应，合成了一系列水溶性的N-烷基吡啶卟啉（1−3）.产物混合物显示出对α α ββ阻转异构体形成的明显偏好。以α-溴代-N-正丁基乙酰胺为原料，一步合成了相应的ααββ 2-四（N-正丁基乙酰胺基）吡啶卟啉（2-TnBuPyP，3），分离收率为69%。长时间加热导致体积较小的烷基的旋转异构体的平衡，表明所观察到的偏好是动力学效应。通过LC/ESI-MS鉴定了N-乙酰基的中间产物，以推断出对所观察到的非统计选择性的解释。
meso-Tetrakis(2-pyridyl)-porphyrin (2-PyP) was tetra-N-alkylated with three different α-bromoacetamides to generate a series of water-solubleN-alkylpyridinium porphyrins (1−3). The product mixtures showed a marked preference for the formation of the ααββ atropisomer. With α-bromo-N-n-butylacetamide, the corresponding ααββ 2-tetrakis (N-n-butylacetamido)-pyridyl porphyrin (2-TnBuPyP,3) was obtained in 69% isolated yield in a single step. Prolonged heating lead to equilibration of the rotational isomers for the less bulky alkyl groups, indicating that the observed preference is a kinetic effect. The intermediate products for theN-bornyl case were identified by LC/ESI-MS to deduce an explanation for the observed nonstatistical selectivity.