Fundamental Principles of BLOCK Design and Assembly in the Production of Large, Rigid Molecules with Functional Units (Effectors) Precisely Located on a Carbocyclic Framework

New cycloaddition reactions have been developed to regiospecifically couple together alicyclic reagents (blocks) containing the same or different functional units (effectors). Dipolar cycloadditions (alkenes plus cyclobutene epoxides and the related aziridines), Diels-Alder cycloadditions (alkenes plus dienes formed from s-tetrazine, 1,2,4-triazine and 1,3,4-oxadiazole) and condensations of α-diones with vic-diamines have been used as the coupling procedures. This new approach is based on a building block strategy where small blocks already containing an attached effector are joined in a simple convergent step to produce large rigid structures (ribbon molecules) containing one or more effector groups precisely positioned both in distance and relative orientation onto an inert carbocyclic frame (a molrac). These effector groups include porphyrins, crown ethers, fluorophores, nucleic acid bases, β-lactams, redox-active components, bidentate ligands of various type, amino acids, intercalators, and metal complexes. All these classes can be joined together either as homo or mixed pairs into rods, spacers or U-shaped cavity structures, whose shapes can be evaluated using molecular modelling (AM1, Sybyl, PM3 etc.).

1,3-dipolar and Diels-Alder cycloaddition - cyclobutene epoxides - s-tetrazines - high-pressure - topology