Stereoselective Wittig Olefination as a Macrocyclization Tool. Synthesis of Large Carbazolophanes

Myśliwiec, D.; Lis, T; Gregoliński, J.; Stępień, M.
J. Org. Chem. 2015, 80, 6300–6312 | view at publisher's site

Z-selective Wittig olefination was applied to the synthesis of large carbazolophanes containing up to 8 heteroaromatic subunits. A number of strategies were devised and tested, showing that cyclooligomerization yields can be significantly improved by using one-component schemes involving heterobifunctional reactants. [4]- and [6]carbazolophanes were characterized in the solid state, revealing compact, highly folded structures. Electronic and steric effects of substitution and chain length on the Wittig olefination rates and Z-selectivities were explored theoretically using DFT calculations.