Premium
Stepwise Synthesis and Selective Dimerisation of Bis‐ and Trisloop Tetra‐urea Calix[4]arenes
Author(s) -
Rudzevich Yuliya,
Cao Yudong,
Rudzevich Valentyn,
Böhmer Volker
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701694
Subject(s) - tetra , urea , chemistry , intramolecular force , hydrogen bond , calixarene , olefin metathesis , metathesis , medicinal chemistry , stereochemistry , organic chemistry , molecule , polymerization , polymer
Tetra‐urea calix[4]arenes substituted with four mono‐ or bisalkenyl residues have been converted into bis‐ or tetraloop compounds by intramolecular olefin metathesis, with use of a tetratosylurea calix[4]arene as template. The same strategy has now been used to synthesise trisloop compounds and bisloop compounds with adjacent loops, completing the series of the loop‐containing tetra‐urea derivatives. A tetra‐urea calix[4]arene of the AABB type, where A stands for a bisalkenyl‐ and B for a monoalkenyl‐substituted urea unit, was used as precursor for the three loops. It was easily synthesised from a tetraamino calix[4]arene in which two adjacent amino groups were Boc‐protected. The ABCB‐type precursor for the two adjacent loops was prepared through protection of two opposite amino functions with trityl groups. The capabilities of the novel macrocyclic tetra‐ureas for the selective formation of hydrogen‐bonded dimers were studied.