SYNTHESIS OF CHIRAL (R)-4-HYDROXY[2.2]PARACYCLOPHANES AND (R)-4-HALOGENO[2.2]PARACYCLOPHANES AND GROUP POLARIZABILITY - OPTICAL-ROTATION RELATIONSHIP

(R)-4-Hydroxy-, -4-fluoro-, -4-bromo-, and -4-iodo[2.2]paracyclophanes have been prepared and their absolute configuration assigned on the b asis of chemical correlations. Different relationships between the spe cific optical rotation and the group polarizability have been found de pending on the ability of the substituents to conjugate with the aroma tic ring. At least for 4,7-disubstituted [2.2]paracyclophanes, the eff ects of the substituents on the specific rotation seem to be additive, independent of the wavelength used. An equation has been derived whic h allows to predict, to a satisfactory approximation, the [a] values o f 4-X-7-methyl[2.2]paracyclophanes whenever the group polarizability o f the substituents is known.