ORthogonal Silane Protecting Group Methods for Modified Sonogashira Couplings

Ambrosi, Gavin, Monica Bugeja, David Dumais, Salette Martinez, Andrew Ward, and Matthew Mio

Iterative oligomerization syntheses of arylethynylenes involving the palladium-catalyzed Sonogashira reaction often require systematic silane protection/deprotection of terminal acetylenes. 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. An orthogonal approach to the generation of these oligomers allows for rapid molecular prototyping, and in turn, increases the accessibility of valuable arylethynyl structures.