Calixpyrroles to Calixpyridines

It was found that when we.w-octamethylcalix[4]pyrrole (1) was reacted with 15 molar equivalents of s ium trichloroacetate (the dichlorocarbene source), a 2.4 1 mixture of the mono- and dipyridine macrocycles (21 and 22) was produced.When the same reaction conditirms were employed using 1,2-dimethoxyethane as the. solvent, a mixture of di- (22a or 22b), tri- (23) and tetrapyridine (20) species was obtained in a 1 I I ratio. Improved yields of 

The pyrrolic-NH groups are oriented towards the pyridine nitrogen atoms such that potential NH- N hydiogen bonds may be formed. While not yet investigated in detail, these putative hydrogen bonds could be. serving to influence the conformational properties of the macrocycle. 

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