Steric Preference in a One-Pot Desilylation Followed by Sonogashira Coupling

Abbo, Reema, Kimberly Coughlin, Brian Greenhoe, Erik Wrubel, and Matthew Mio

Our group reports a modification of the Sonogashira cross-coupling reaction that allows for a sterically-selective one-pot generation of arylethynylenes. Our findings reveal that in the presence of increasing steric bulk of silane-protected acetylenes, trimethylsilyl groups are preferred in a one-pot coupling reaction with amidine base (1,8-diazabicyclo[5.4.0] undec-7-ene, DBU) and the presence of sub-stoichiometric amounts of water, in addition to Pd catalyst, CuI and organic solvent. Using the size of the protecting group as a synthetic guidepost, new methods for the iterative synthesis of arylethynyl oligomers is also reported.