[2.2]Paracyclophane Derivatives: Synthesis and Application in Catalysis

Abstract

Advances in the field of [2.2]paracyclophane chemistry are reviewed including syntheses, resolution of enantiomers and application in organic synthesis. Transition-metal catalyzed as well as organocatalytic transformations are presented focusing on the development of [2.2]paracyclophane derived ligands and catalysts.

Homochiral [2.2]Paracyclophane Self‐Assembly Promoted by Transannular Hydrogen Bonding

“…The synthetic chemistry of pCp is quite mature and allows functional groups to be precisely positioned on the rings and bridges—two common ring substitution patterns are shown in Figure b. Synthetic organic chemists continue to use the planar chirality associated with appropriately functionalized pCps in ligand and catalyst design to great effect, while work by the groups of Bazan, Chujo, Collard, and others has beautifully evaluated the consequences of through‐space conjugation on the properties of covalent π‐conjugated oligomers and polymers featuring embedded pCps. Indeed, the pCp building block remains attractive for organic optoelectronic applications ranging from nonlinear optics to photovoltaics …”

A new protocol for the synthesis of 4,7,12,15-tetrachloro[2.2]paracyclophane

“…Therefore, the two chloride atoms on the benzene ring make parylene D superior to parylene N and parylene C. There are some creative strategies for the synthesis of 4,7,12,15-tetrachloro[2.2]paracyclophane (Fig. 2), the precursor of parylene D [8]. Theoretically, direct chlorination of [2.2]paracyclophane is an ideal route to prepare tetrachloroparacyclophane, but a pure polysubstituted product is difficult to obtain by electrophilic substitution without repeated crystallization or chromatographic purification [9].…”

An Asymmetric Variant of the Bischler–Möhlau Indole Synthesis

“…[3][4][5] [2.2]Paracyclophane provides a versatile platform for the synthesis of planar chiral molecules and such compounds have found use in asymmetric synthesis [6][7][8] and the development of new materials and polymers. [2,[9][10][11][12] Many racemic heterocyclic [2.2] paracyclophane derivatives have been reported but few have been resolved and as a result their full potential has not been realised. [13] We have a long standing interest in the preparation of planar chiral heterocycles having synthesised [2.2]paracyclophane-derived benzimidazoles, [14] imidazoles, [15] pyridines, [16,17] triazoles, [18] and a benzothiazole.…”