Room-Temperature, Copper-Free Sonogashira Reactions Facilitated by Air-Stable, Monoligated Precatalyst [DTBNpP] Pd(crotyl)Cl.

A novel application of [DTBNpP] Pd(crotyl)Cl (DTBNpP = di-tert-butylneopentylphosphine) (P2), an air-stable, commercially available palladium precatalyst that allows rapid access to a monoligated state, has been identified for room-temperature, copper-free Sonogashira couplings of challenging aryl bromides and alkynes. The mild reaction conditions with TMP in dimethyl sulfoxide afford up to 97% yields, excellent functional group tolerability, and broad reaction compatibility with access to one-pot indole formation.