An unexpected bidirectional molecular rotor from unidirectional molecular motor via a stereoselective enamine-imine tautomerization process
writer：Jingpeng Xiong, Quan Li*, Ming-Hua Zeng
keywords：molecular motor, molecular rotor, stereoselectivity, external stimuli
source：期刊
specific source：Tetrahedron Letters
Issue time：2020年
Developing stereoselective synthetic method is very important to access chiral molecular devices. We herein demonstrate how a proton initiated stereoselective enamine-imine tautomerization converts a molecular motor into a simple rotor with high diastereoselectivity (>20:1 dr). NMR and X-ray crystallography were used to elucidate the structures of both the motor and rotor unambiguously. The activated motion of the rotor about its central single bond was studied from variable temperature NMR (293 - 423 K) and DFT calculations provide evidence of the origin of diastereoselectivity of enamine-imine tautomerization as well as the rotor dynamics with barrier as high as 39.3 kcal/mol. Results from our work may benefit future design towards stereocontrolled and adaptive molecular machines.