Selective formation of the rctt chair stereoisomers of octa-O-alkyl resorcin[4]arenes using Bronsted acid catalysis

Article abstract of DOI:10.1039/b714735j

New synthetic conditions are described for the fully selective formation of the rctt chair stereoisomers of octa-O-alkyl resorcin[4]arenes; these offer a clean route into the chair conformer of these interesting receptor molecules. Bronsted acid catalysis in acetic acid solutions results in the formation of the single isomer when 1,3-dimethoxybenzene is heated at 80 °C with a range of aldehydes, straight- and branched-chain or aromatic, and with an aldehyde synthon. An investigation of reaction conditions indicated that, in this case, the rctt chair stereoisomer was the thermodynamic product, a result confirmed by molecular modelling studies that show that this stereoisomer is of lower energy than the expected rccc boat stereoisomer. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.