An improved synthesis of ( S )-(+)- and ( R )-(−)-[2.2]paracyclophane-4-carboxylic acid

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

“…Thes ynthesis of (AE)-1 (Figure 1f;s ee Scheme S1) progressing through intermediates 2-5 began from commercially available pCp,w hich was tetrabrominated in the manner reported by Reich and Cram, [24] converted into its tetraacid through lithium-halogen exchange followed by quenching with CO 2 ,a sr eported by Rozenberg and co-workers for the synthesis of pCp mono-and diacids, [25] and finally converted into the aliphatic amide derivatives (AE)-1a and (AE)-1b using standard chemistry.T he hexyl version affords particularly good solubility in organic solvents.Asimilar synthetic approach was used to prepare monoamide (AE)-6b,w hich is useful as ac omparator molecule to report on the hydrogenbonding properties of (AE)-1.…”

Roadmap towards N‐Heterocyclic [2.2]Paracyclophanes and Their Application in Asymmetric Catalysis

“…Starting with [2.2]paracyclophane amide ( 23 ), triazolyl functionalized [2.2]paracyclophanes are accessible. Compound 23 was synthesized by following a process developed by Reich et al,21 involving treatment of racemic bromo[2.2]paracyclophane with n BuLi and then with dry‐ice to give carboxy[2.2]paracyclophane 22. The acid was activated with SOCl 2 and the acid chloride was quenched with aqueous ammonia to give 23 in 92 % yield 23.…”

Synthesis of Pseudo-geminal-, Pseudo-ortho-, andortho-Phosphinyl-oxazolinyl-[2.2]paracyclophanes for Use as Ligands in Asymmetric Catalysis

“…The increased shielding occuring in 3b is attributed to delocalization of electron density from the P-lone pair, through the π-system, onto the N-atom of the oxazoline ring. Correspondingly, 31 P NMR of 3b shows the P-atom to be more deshielded (1.48 ppm) than that of 3a (0.20 ppm). In conclusion, 3b must have the oxazoline, Plone pair and [2.2]paracyclophane aromatic ring in conjugation, whereas 3a does not.…”