Crystal Structure of rac-4-Iodo-5-methoxy[2.2]metacylophane; A Rare Example of a Halogenated Metacyclophane with Planar Chirality

A racemic mixture of planar chiral 4-iodo-5-methoxy[2.2]metacylophane (2) was synthesized by the low-temperature directed ortho aryl metalation of 5-methoxy[2.2]metacyclophane (1) and subsequent in situ reaction with iodine. The crystal structure was determined by the single-crystal X-ray diffraction method at 100 K. The compound crystallized in an orthorhombic system and was characterized as: Pca21, a = 13.5690(2), b = 14.2212(2), c = 7.5004(1)Å, Z = 4, V = 1447.33(4)Å3. The crystal structure was solved by direct methods and refined by full-matrix least-squares on F2 to final values of R1 = 0.0281 and wR2 = 0.0733 for all 3021 independent reflections.