The synthesis and binding properties of new macrocyclic polyethers are described. These systems incorporate 2,2'bipyridyl functions in such a fashion that binding of metal nuclei can occur at either the macrocycle or the bipyridyl function. Evidence is presented that binding of alkali metals occurs at the crown ether cavity while binding of transition metals occurs at the bipyridyl function. Binding of two different metals is interpreted in terms of a simple model for allosteric effects.

TMEDA (5.8 g, 7.55 mL, 0.5 mol) was added. The solution was chilled in an ice bath and n-butyllithium (31.4 mL of a 1.6 M solution in hexane, 0.05 mol) was added dropwise. The turbid solution was allowed to warm up to room temperature and then heated under reflux overnight (20 h). During this lithiation period a tannish-yellow precipitate formed. The mixture was again cooled in an ice bath and quenched by dropwise addition of a solution of dimethyl sulfate (6.94 g, 5.2 mL, 0.55 mL) in 50 mL of ether. The precipitate became more dense and turned white. After being stirred for 3 h, the mixture was poured over ice-water, the ether layer was separated, and the aqueous layer was extracted with ether. The combined ether extracts were washed with 2 N NH4OH, 2 N HC1, water, and brine and then dried (MgSQ4) and concentrated. The yellow residue was recrystallized from pentane: mp 168-169 °C;

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The application of a binding force (the chelation of a metal by a 2,2,-bipyridyl) to enhance reaction rates is examined with three systems. Metals are shown to increase the rate of cyclization of certain 3,3'-disubstituted, 2,2'-bipyridyl derivatives. Similar effects are seen in the elimination reaction of an appropriate halide and the racemization of asymmetric bipyridyl crown ethers. The last case involves catalysis according to the Pauling principle of maximum binding to the transition state. The relevance of these findings to biochemical processes is discussed.

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