Microwave-assisted iridium catalyzed [2+2+2] cycloaddition of resin bound dipropargylamine with various alkynes
Transition metal mediated [2+ 2+ 2] cycloadditions is a useful strategy to create polysubstituted benzene derivatives like isoindolines. In addition isoindoline scaffolds have become interesting to researchers because of the diversity that can be included and because of the potential they have as biological agents. However, the persistent problems of dimerization and trimerization of diyne and alkyne in solution phase cycloaddition require an optimal method. Moreover transition metal mediated cycloadditions have a tendency of having high heat or photochemical processes, and long reaction times. The issue of self trimerization of the alkyne, dimerization, and trimerization of the aminodiyne was addressed by immobilizing the diyne on a solid support. Furthermore a microwave-assisted iridium-catalyzed [2 +2 +2] cycloaddition method was developed meanwhile affording isoindoline derivatives in moderate yields. This method was able to shorten the reaction times 25 fold from those used in thermal conditions and required no column chromatography due to easy work up procedures and simple filtration. In addition the proposed reaction is used to further diversify the immobilized dipropargylamine by reacting it with olefins, acrylates, and aldehydes. However this reaction proved to be more challenging due to the additional byproduct formation and possible tuning of catalyst and ligand. To create further diversity resin bound 3'3-iminodipropionitrile was used to undergo iridium catalyzed [2+2+2] cycloaddition using the standard method that was developed. Moreover the failure of this reaction is discussed in the proposed research.
Aguirre, Ana Luisa, "Microwave-assisted iridium catalyzed [2+2+2] cycloaddition of resin bound dipropargylamine with various alkynes" (2006). ETD Collection for University of Texas, El Paso. AAI1439492.