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

Abstract

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.

Cycloaddition Reactions of Cobalt-Complexed Macrocyclic Alkynes: The Transannular Pauson–Khand Reaction

“…Specifically, dicobalt octacarbonyl has been used in many [2 + 2 + 2] cycloadditions . Transannular [2 + 2 + 2] cycloadditions of macrocyclic triynes are also known; however, to the best of our knowledge, this is the first example of an intermolecular cyclotrimerization involving a macrocyclic dicobalt hexacarbonyl alkyne complex.…”

The Choice of Rhodium Catalysts in [2+2+2] Cycloaddition Reaction: A Personal Account

“…Encouraged by the results with our macrocyclic systems, we extended the totally intramolecular cycloaddition reaction to a large range of unsaturated azamacrocycles. The macrocycles differ in the ring size (15-, 16-, 17-, 20-, and 25-membered), the number and type of unsaturations (triacetylene and enediyne macrocycles with (Z) and (E) geometry), and the presence of substituents either in the double bond or in the α-position relative to the triple bond [18][19][20]. The cycloaddition reaction was run using a 10% molar of RhCl(PPh 3 ) 3 in toluene at temperatures from 60 • C to reflux affording excellent yields of the corresponding fused tetracycles with benzene and cyclohexadiene cores.…”