高圧不斉光化学反応—圧力による生成物キラリティーの制御—

抄録

Pressure effects upon asymmetric photochemical reactions are discussed in the context of entropy control of these reactions. In the enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to chiral (E)-isomer (1E) sensitized by chiral aromatic esters (2-7), the 1E/1Z ratio and the enantiomeric excess (ee) of 1E are critical finctions of the applied pressure, accompanying an unprecedented switching of the product chirality. Furthermore the differential activation parameters (ΔΔH^‡, ΔΔS^‡ and ΔΔV^‡) obtained by changing pressure and temperature cleary indicate that these variants act as independent factors in the enantiodifferentiating process. This opens a new channel to the multidimensional control of not only asymmetric photochemical but also conventional thermo/photo/biochemical reactions in which weak interactions are the principal driving force or determining factor.