Synthesis of Chiral (R)-4-Hydroxy- and (R)-4-Halogeno[2.2]paracyclophanes and Group Polarizability. Optical Rotation Relationship

Abstract

(R)-4-Hydroxy-, -4-fluoro-, -4-bromo-, and -4-iodo[2.2]paracyclophanes have been prepared and their absolute configuration assigned on the basis of chemical correlations. Different relationships between the specific optical rotation and the group polarizability have been found depending on the ability of the substituents to conjugate with the aromatic ring. At least for 4,7-disubstituted [2.2]paracyclophanes, the effects of the substituents on the specific rotation seem to be additive, independent of the wavelength used. An equation has been derived which allows to predict, to a satisfactory approximation, the [α] values of 4-X-7-methyl[2.2]paracyclophanes whenever the group polarizability of the substituents is known.

Chiroptical Signatures of Planar and Central Chirality in [2]Paracyclo[2](5,8)quinolinophane Derivatives

“…In that case, additivity rules based on the group polarizability-OR correlation for chiral 4-substituted [2.2]-paracyclophanes, were also derived. [9] ECD was also used to test semiempirical computational methods on the same paracyclophane compounds [10] and they were among the first molecules for which time-dependent density functional theory (TDDFT) calculations were performed. [11,12] Our approach is reminiscent of the investigations performed by Mori, Inoue and Grimme in the paracyclophane field.…”

Resolution and Novel Reactions of 4-Hydroxy[2.2]paracyclophane

“…[8] Two routes to the enantiomers of 1 have previously been described: On the one hand a three-step synthesis of (R)-1 from (R)-4-amino [2.2]paracyclophane, which in turn is obtained by resolution of the racemic amine; however, this method is not very efficient because of the quite low overall yield. [9] On the other hand, the lipase-catalyzed enzymatic kinetic resolution of 4-acetoxy [2.2]paracyclophane (2), independently proposed by two groups, [10,11] is more effective. Thus, under optimal conditions, the resolution of 0.6 mmol of racemic 2 resulted in optically pure (S)-2 (ee Ͼ 99%, chem.…”

Chemoenzymatic Synthesis of Optically Pure Planar Chiral (S)-(–)-5-Formyl-4-hydroxy[2.2]paracyclophane

“…Recently, we [10] and against oxidation and racemization under acidic or basic others [11] similarily reported on the enzyme-catalyzed kineconditions [2] . Therefore, much effort was made to show that tic resolution of 4-acetoxy-[2.2]paracyclophane (1).…”

“…Chem. 1998, 1441Ϫ1445 [14] in the paper of Cipiciani et al [11] . phane (1) [10] were tested for the resolution of 4-acetoxy-5-formyl[2.2]paracyclophane (4).…”