= Solution
\b[Reversible imine formation and disulfide exchange] provide two suitable <dynamic covalent chemistry> reactions.
An <aldehyde> and a primary <amine> can reversibly form an <imine> with loss of water:
$$
\mathrm{RCHO+H_2NR'\rightleftharpoons RCH{=}NR'+H_2O}.
$$
Multifunctional components can build rings or cages. Acid catalysis, solvent and water activity must permit both formation and hydrolysis or exchange, so that initially incorrect connections can rearrange.
For <disulfide exchange>, a thiolate attacks a disulfide and substitutes one sulfur-containing fragment:
$$
\mathrm{R'S^-+RSSR\rightleftharpoons R'SSR+RS^-}.
$$
Suitable pH, redox conditions and exchange kinetics let a library of connectivities equilibrate. A template that stabilizes one assembly can shift the library towards it. \b[Reversibility under the actual conditions is essential]: calling a covalent reaction “dynamic” does not make a kinetically trapped product mixture equilibrate.
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