Orthogonal Silane Protecting Group Methods for Modified Sonogashira Couplings

Bugeja, Monica, David Dumais, Salette Martinez, Andrew Ward, Branden Yaldou, and Matthew Mio

The palladium-catalyzed Sonogashira reaction has proven to be a superior method for alkynylation, especially in the case of arylethynylenes. While iterative syntheses often require systematic silane protection/deprotection of terminal ethynylenes, our group has devised a modification of the Sonogashira reaction that allows for the one-pot generation of symmetrical bisarylethynylenes in the presence of bulkier silane-protected acetylenes. Central to the modification‟s synthetic protocol is the utilization of an amidine base such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and the presence of substoichiometric amounts of water, in addition to Pd catalyst, CuI and organic solvent. The advent of orthogonal approaches to the generation of such oligomers should allow for rapid molecular prototyping, and in turn, increase the accessibility of valuable supramolecular and nanoscale systems.