Dynamic Libraries From Imine Metathesis

Inspection of NMR spectra of the equilibrates, coupled with DOSY and mass spectrometry measurements, allowed the determination of 

Obviously, the previously mentioned method can be generalized and used as an alternative protocol for the evaluation of EM values when the more accurate procedure based on the direct measure of a ring equilibrium concentration in a DL close to the critical concentration, is not available. 

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Fig. 27 Examples of thermodynamically controlled reactions employed in the near-quantitative synthesis of MIMs. (a) Disulfide-exchange reaction permits equilibration between a bis(ammo-nium) disulfide dumbbell and a crown ether macrocycle to yield a mixture of [2]- and [3]rotaxanes quantitatively [194], (b) Olefin metathesis at high concentration on a benzylic amide macrocycle greatly favors the catenated species [196]. (c) Self-correcting imine bonds allow for nearly quantitative selection of a [2]rotaxane from an appropriate dynamic combinatorial library [76], (d) A weak nucleophile (E) equilibrates the components of a donor-acceptor [2]catenane in a dynamic Sn2 reaction [205]...

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