Silylacetylene protecting group sterics allow for synthetic orthogonality in a modified Sonogashira coupling reaction

Barbour, Kimberly, Theresa Dierker, Rachel Beltman, Michael Ponkowski, Joseph Samona, Roby Wong, and Matthew Mio

Modified Sonogashira coupling reactions have been developed that allow for synthetic control of reactive sites based on the steric size of the terminal acetylene protecting group. An amidine base, such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), the presence of substoichiometric amounts of water, in addition to Pd catalyst, CuI and organic solvent are all required for these transformations to proceed with good yield. This orthogonal approach to the generation of sequence-specific oligomers could increase the accessibility of high value-added arylethynyl structures, where highly-repetitive syntheses are common.