New calix[4]resorcinol rccc diastereoisomer with terminal triple bonds: Synthesis, structural features and reactions

One-pot acid-catalyzed cyclocondensation of 2-methyl-resorcinol with 4-(propargyloxy)benzaldehyde in CHCl₃/CF₃CO₂H media affords all-cis (rccc) and/or cis-trans-trans (rctt) calix[4]resorcinol diastereomers bearing four terminal alkyne groups at aromatic substituents, the isomer ratio and yield being dependent on the CHCl₃/CF₃CO₂H ratio. The rctt isomer (kinetic control product) can be converted to thermodynamically more stable rccc isomer at prolonged refluxing in CHCl₃/CF₃CO₂H mixture. The rccc diastereomer was subjected to additional propargylation followed by the click reactions with benzylic azides to afford new highly triazolated calix[4]resorcinols.