Chiral recognition by CD-sensitive dimeric zinc porphyrin host.: 1.: Chiroptical protocol for absolute configurational assignments of monoalcohols and primary monoamines
Chiral recognition by CD-sensitive dimeric zinc porphyrin host.: 1.: Chiroptical protocol for absolute configurational assignments of monoalcohols and primary monoamines
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DOI：
10.1021/ja010249w
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发表时间：
2001-06-27
影响因子：
15
通讯作者：
Berova, N
中科院分区：
文献类型：
--
作者：
Kurtán, T;Nesnas, N;Berova, N
描述了用于测定连接到单个立构中心的伯氨基或仲羟基的绝对构型的通用微尺度方案，手性底物连接到非手性三功能双齿载体分子(3-氨基丙氨基)乙酸(1，H2NCH2CH2CH2NHCH2COOH)，然后将所得缀合物与二聚锌卟啉主体2复合，产生1:1主体/客体夹心复合物。由于立体分化导致优选的卟啉螺旋性，这些配合物表现出激子耦合的双峰圆二色光谱。由于复合物中两个卟啉之间的手性扭曲由底物的立体中心决定，因此对的符号决定了该中心的绝对构型。复合物中卟啉镊子的扭曲可以根据立体中心两侧基团的相对空间大小来预测。使得体积较大的基团从复杂的三明治中突出。在某些α-羟基酯和α-氨基酯中，电子因子和氢键控制复合物的优选构象，从而控制圆二色光谱。
A general microscale protocol for the determination of absolute configurations of primary amino groups or secondary hydroxyl groups linked to a single stereogenic center is described, The chiral substrates are linked to the achiral trifunctional bidentate carrier molecule (3-aminopropylamino)acetic acid (1, H2NCH2CH2CH2NHCH2COOH) and the resultant conjugates are then complexed with dimeric zinc porphyrin host 2 giving rise to 1:1 host/guest sandwiched complexes. These complexes exhibit exciton-coupled bisignate CD spectra due to stereodifferentiation leading to preferred porphyrin helicity. Since the chiral sense of twist between the two porphyrins in the complex is dictated by the stereogenic center of the substrate, the sign of the couplet determines the absolute configuration at this center. The twist of the porphyrin tweezer in the complex can be predicted from the relative steric sizes of the groups flanking the stereogenic center. such that the bulkier group protrudes from the complex sandwich. In certain alpha -hydroxy esters and alpha -amino esters, electronic factors and hydrogen bonding govern the preferred conformation of the complex, and hence the CD spectra.