On the Nature of CH⋅⋅⋅FC Interactions in Hindered CF3C(sp3) Bond Rotations
作者:G. K. Surya Prakash、Fang Wang、Martin Rahm、Jingguo Shen、Chuanfa Ni、Ralf Haiges、George A. Olah
DOI:10.1002/anie.201105288
日期:2011.12.2
scaffolds, hinderedCF3rotations have been observed. The variation in barrier heights for the CF3rotations is controlled by the corresponding entropic changes when the substituents are changed from an allyl to a bulky 9‐methylanthracenyl group. Quantum chemical and experimental studies have shown that the noncovalent C3′H1⋅⋅⋅FCinteractions in the studied cases possess a weak hydrogen bonding‐like character
在基于金鸡纳生物碱的支架中,观察到CF 3旋转受阻。当取代基从烯丙基变为大体积的9-甲基蒽基时,CF 3旋转的势垒高度的变化由相应的熵变化控制。量子化学和实验研究表明,所研究案例中的非共价 C3′ H1⋅⋅⋅F C 相互作用具有弱氢键性质。
Conformational Study of 9-Dehydro-9-Trifluoromethyl Cinchona Alkaloids via <sup>19</sup>F NMR Spectroscopy: Emergence of Trifluoromethyl Moiety as a Conformational Stabilizer and a Probe
作者:G. K. Surya Prakash、Fang Wang、Chuanfa Ni、Jingguo Shen、Ralf Haiges、Andrei K. Yudin、Thomas Mathew、George A. Olah
DOI:10.1021/ja202373d
日期:2011.7.6
The trifluoromethyl substituent has been incorporated into quinidine as a conformational stabilizer and a probe to provide straightforward insight into the conformational behavior of cinchonaalkaloids. By significantly decreasing the rotation rate of the quinoline-carbinol bond, the relatively bulky CF(3) group enables the NMR signals of the syn and anti conformers to be differentiated at room temperature