Can. J. Chem. 63, 3298 (1985).The crystal structure of a chiral rn-cyclophane, the a-isomer of (S)-a-methoxy-a-(trifluoromethyl)phenylacetate ester of 13-(methoxycarbonyl)-14-hydroxy-17-methyl-[I I]-m-cyclophane (C30H3705F3r FW = 534.62) has been solved by direct methods and refined by a least-squares procedure to a final R = 0.048 for 2756 independent r~flections. The crystals belong to the orthorhombic system, a = 10.8077(13), b = 13.676(3), c = 19.060(4) A, V = 2817.2 A', Z = 4, and the space group is P2,2,2,. The absolute configuration of the chiral plane, using the S-configuration of the a-methoxy-a-(trifluoromethy1)phenylacetate ester as reference, is found to be S, in agreement with the X-ray result. The 14-membered ring has the slightly distorted rectangular conformation that has been described by Dale as the rectangular diamond-lattice conformation [3434]. The distortions, also observed in similar 14-membered rings, have been successfully approximated by molecular mechanics calculations.
IntroductionWe recently reported (1, 2) on the first successful optical resolution of a number of intraannularly substituted chiral mcyclophanes such as 1 and 2. The existence of enantiomerism in these compounds, which belong to the class of "planar"