Rhodium(I)-Catalyzed [2 + 2 + 2] Cycloaddition Reactions of Triacetylenic 15-Membered Aza Macrocycles: A Comparative Structural Study

A variety of new nitrogen-containing 15-membered triacetylenic
macrocycles with one or two alkyl substituents in a propargylic position
have been efficiently synthesized and completely characterized. These
macrocyclic systems undergo [2 + 2 + 2] cycloaddition reactions, leading
to the corresponding fused tetracycles with a benzene core on treatment
with Wilkinson’s catalyst, [RhCl­(PPh3)3]. The effects of alkyl chains have been evaluated on both the efficiency
of the reaction and the conformational and structural analysis of
the reactants.