作者:Misbah Ul Hasan、M. Arab
DOI:10.1002/mrc.1260251113
日期:1987.11
The 13C shifts in several N-chloro-2,6-diarylpiperidin-4-ones have been measured and compared with previously reported sifts in the corresponding 2,6-diarylpiperidones. The shifts of the α-carbons in these compounds move downfield by 12–13 ppm, which can be attributed to the increased electronegativity of the nitrogen atoms. The changes in the chemical shifts of the β-carbons are minimal. Surprisingly, the absorptions of the carbonyl carbons move upfield by as much as 4.0 ppm. The magnitude of the shift in the resonance of the carbonyl carbon indicates the possibility of a transannular interaction between the nitrogen and the carbonyl group, which has not previously been observed in these systems. A preferred conformation for the aryl group in these compounds is also proposed.
对几个N-氯-2,6-二芳基哌啶-4-酮的13C化学位移进行了测量,并与先前报告的相应2,6-二芳基哌啶酮的位移进行了比较。这些化合物中α碳的位移向下移动了12-13 ppm,这可以归因于氮原子电负性的增加。β碳的化学位移变化则很小。令人惊讶的是,羰基碳的吸收向上移动了多达4.0 ppm。羰基碳的共振位移幅度表明氮与羰基之间可能存在跨环相互作用,这在这些体系中尚未被观察到。此外,还提出了这些化合物中芳基的首选构象。