150096-57-4Relevant articles and documents
Fluorine-Substituted Molecular Motors with a Quaternary Stereogenic Center
?tacko, Peter,Kistemaker, Jos C. M.,Feringa, Ben L.
, p. 6643 - 6653 (2017)
A series of unprecedented second generation molecular motors featuring a quaternary stereogenic center substituted with a fluorine atom has been synthesized. It is demonstrated that a seemingly benign replacement of the stereogenic hydrogen for a fluorine atom, regarded as a common substituent in pharmacology, resulted in a dramatic change in the energetic profile of thermal helix inversion. The barrier for the thermal helix inversion was found to increase considerably (by 20–30 kJ mol?1), presumably due to destabilization of the transition state by increased steric hindrance when the fluorine atom is forced to pass over the lower half of the motor. This results in the activation barrier for the thermal helix inversion to be higher than the barrier for backward thermal E–Z isomerization, impairing the motor function. A fluorine-substituted motor capable of performing unidirectional rotation is successfully prepared when these limitations are considered in the design phase.
Transition metal compound, catalyst composition comprising same, and method for producing olefin polymer using same
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, (2019/05/18)
The present invention provides a transition metal compound, a catalyst composition comprising the same, and a method for producing an olefin polymer using the catalyst composition, the transition metal compound being capable of exhibiting high activity in olefin polymerization reaction, and also being capable of easily controlling the physical properties of an olefin polymer. When the transition metal compound is used, it is possible to provide an olefin polymer having an excellent energy-saving effect at the time of processing or molding.
A new model of light-powered chiral molecular motor with higher speed of rotation, part 1 - Synthesis and absolute stereostructure
Fujita, Takuma,Kuwahara, Shunsuke,Harada, Nobuyuki
, p. 4533 - 4543 (2007/10/03)
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/LiAlH4, 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. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
