Synthesis, Modification, and Characterization of a Family of Homologues of exo-Calix[4]arene:  exo-[n.m.n.m]Metacyclophanes, n,m ≥ 3

Abstract

A general strategy for the preparation of the family of exo-[n.m.n.m]metacyclophanes (n,m > or = 3) in 6-steps (starting from 2-bromoanisole) that utilizes a [2 + 2] approach to furnish the exo-metacyclophane ring in good to moderate yield is described. The soluble copper catalyst [CuBr-LiSPh-LiBr-THF] is used to efficiently couple Grignard and alkyl or ether tosylate reagents in several of the synthetic steps, including the ring construction in the final step. The exo-[n.m.n.m]metacyclophane ring is conformationally mobile on the NMR time scale, and X-ray crystallography reveals that exo-[3.3.3.3]metacyclophane 2a assumes a cone conformation, and that exo-[6.6.6.6]metacyclophane 6a assumes a chair conformation. Molecular mechanics calculations show that both conformations for each exo-metacyclophane are very similar in energy. Regiocontrol over the alkylation and acylation of the phenolic oxygens of 2b is problematic, although the preparation of the tetraacetylated 18 and alkylation of 2b with CH2BrCl to furnish the methylene-linked mono- and bis-adducts 19 and 20 are straightforward.

Investigation of an 18F-labelled Imidazopyridotriazine for Molecular Imaging of Cyclic Nucleotide Phosphodiesterase 2A

“…and ethane-1,2-diyl bis(4-methylbenzenesulfonate) (0.17 g, 2 eq. ; synthesized according to the literature [ 19 , 57 ]) were added. After stirring at 60–70 °C for 5 h and at ambient temperature overnight, the yellow suspension was filtered followed by evaporation of the solvent.…”

Synthesis, 18F-Radiolabelling and Biological Characterization of Novel Fluoroalkylated Triazine Derivatives for in Vivo Imaging of Phosphodiesterase 2A in Brain via Positron Emission Tomography

“…The synthesis of various alkyl bis(4-methylbenzenesulfonates) is already reported [48] and was performed according to the literature. A solution of propane-1,3-diol or butane-1,4-diol (1 eq.)…”

Two similar dibenzo cyclic ethers with dissimilar conformations

“…1). This structure is readily available in good yield by coupling appropriate Grignard and bis-tosylate reagents with the use of our soluble Cu I catalyst (Burns et al, 1997(Burns et al, , 2000. The ortho positions on the bisphenol can be elaborated via aromatic electrophilic addition to provide for the anion-binding unit, while the brominesubstituted para positions can be elaborated via organometallic reactions to provide the hydroxyl-binding unit.…”