A Convergent Synthesis of Hexahomotriazacalix[3]arene Macrocycles

A new, convergent synthesis of hexahomotriazacalix[3]arenes 1a−e is described. The key transformation in this synthesis involves the coupling of the triamines 4a−d with 2,6-bis(chloromethyl)-4-methylphenol 5 and results in the formation of the hexahomotriazacalix[3]arenes 1a−d in 90−95% yield. The triamines 4a−d were constructed by the one-pot reaction of monochloroaldehyde 3 and a primary amine followed by reduction to yield the triamines 4a−d in 50−55% yield. Deallylation of macrocycle 1d was accomplished by palladium catalysis to obtain the N-unsubstituted macrocycle 1e, which has the potential to be a precursor to a variety of N-substituted hexahomotriazacalix[3]arenes.