Wide Rim Urethanes Derived from Calix[4]arenes:Synthesis and Self-Assembly

摘要

Calix[4]arenes 4,substituted at the wide rim by four N-tolyl-urethane groups,were synthesized,as well as derivatives 10a,b bearing two or three tolyl-urea groups beside of one or two urethane group(s).In contrast to tetra-tolyl urea 11,the urethane derivatives do not form hydrogen-bonded,dimeric capsules in CDCl_3 or benzene-d_6,but the dimerization can be induced for the triurea 10b by tetraethylammonium cations as guests.The quantitative formation of heterodimers is observed for all urethanes 4 and 10a,b in benzene-d_6 in mixtures with a "tetra-loop" tetraurea 14,while "bisloop" tetraureas 13 require di- or triurea derivatives 10a,b for a clean heterodimerization.