Cavity-Extended Inherently Chiral Resorcin[4]arenes: Synthesis and Chiroptical Properties of the Cycloenantiomers

Inherently chiral resorcin[4]arenes 2 and 3 were prepared from enantiomerically pure C4‐symmetric rccc‐2,8,14,20‐tetraisobutyl‐4,10,16,22‐tetra‐O‐methylresorcin[4]arene (1). The four 2‐bromobenzyl ether residues in precursor 2 were introduced as halide moieties to partake in an intramolecular Pd‐catalysed C–C cross‐coupling reaction to give tetrabiaryl ether compound 3. The absolute configurations could be derived from the starting compounds and were assigned as (M,R)‐(–)‐2 and (P,S)‐(+)‐2 for the tetrakis(2′‐bromobenzyl) ether compounds as well as (M,R)‐(–)‐3 and (P,S)‐(+)‐3 for the cavity‐extended resorcinarenes. The carbon scaffold of 3 contains four new stereogenic axes whose configurations were assigned by single‐crystal X‐ray analysis. The simulation of the CD spectra by time‐dependent Pariser–Parr–Pople calculations (TDPPP) based on the X‐ray data gave very good images of the experimental spectra. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)