A New Model of Light-Powered Chiral Molecular Motor with Higher Speed of Rotation,Part 1-Synthesis and Absolute Stereostructure

摘要

To develop a molecular motor with a higher speed of rotation,a new model light-powered chiral molecular motor 2 of five-membered ring type was designed,and the motor rotation isomers (-)-2a and (-)-2c were directly synthesized in enantiopure forms for the first time from the ketone (+)-8.The precursor alcohols 9 and 10 were enantioresolved by the camphorsultam-dichlorophthalic acid (CSDP acid;3) method,and their absolute configurations were determined by X-ray crystallographic analysis of the CSDP ester (-)-11b and chemical correlations.The enantiopure ketone (S)-(+)-8 formed from (1S,2S)-(+)-9 or (1R,2S)-(-)-10 was subjected to the McMurry reaction with TiCl_3/LiAlH_4,yielding the motor rotation isomers [CD(-)257.8]-(2S,2'S)-(M,M)-(E)-(-)-2a and [CD(-)270.0]-(2S,2'S)-(M,M)-(Z)-(-)-2c.These studies enabled us unambiguously to determine the absolute stereo-structure of the motor 2,which is of critical importance for control over the direction of motor rotation.