Concave reagents, 8. Concave pyridines and 1,10‐phenanthrolines with sulfonamide bridgeheads. Increased basicity by 4‐diethylamino substitution of the pyridine unit

Bimacrocyclic concave pyridinebissulfonamides 2 and concave 1,10‐phenanthrolinebissulfonamides 4 have been synthesized by bridging macrocyclic pyridinediamines 12 or 1,10‐phenanthrolinediamines 16 with alkylenebis(sulfonyl chloride)s 14 . In contrast to concave pyridine‐ and 1,10‐phenanthrolinebislactams 1 and 3 , the new compounds 2 and 4 exhibit simpler 1 H‐NMR spectra and sharper melting points due to the absence of amide conformers; in comparison to 1 , the basicities of 2 are decreased by a factor of ca. 100. By introduction of donor substituents into the 4‐position of the pyridine ring the basicity loss can be easily compensated. The 4‐diethylamino substituent increases the basicity of the concave pyridines 1 and 2 as expected (ca. + 4 p K units). Since no deviations from the expected basicity and reactivity for the amino‐substituted concave pyridines 1 and 2 have been found, also in these sterically hindered pyridines, the pyridine nitrogen atom is the centre of basicity and reactivity. – The synthesis of new building blocks is described, i.e. 4‐diethylamino‐2,6‐pyridinedicarbaldehyde ( 9c ), the polyether‐based bis(sulfonyl chloride) 14b , the monomacrocyclic diamines 12e–h with a pentaethyleneglycol chain or a 4‐diethylamino substituent.