Chemo-selective Stille-type coupling of acyl-chlorides upon phosphine-borane Au(i) catalysis.

Phosphine-boranes do not promote oxidative addition of acyl chlorides to gold, but the phosphine-borane gold triflimide complex [ i Pr 2 P( o -C 6 H 4 )BCy 2 ]AuNTf 2 was found to catalyze the coupling of acyl chlorides and aryl stannanes. The reaction involves aryl/chloride-bridged dinuclear gold(i) complexes as key intermediates, as substantiated by spectroscopic and crystallographic analyses. Similar to Pd(0)/Pd(ii)-catalyzed Stille coupling with phosphine-borane ligands, the gold-catalyzed variant shows complete chemoselectivity for acyl chlorides over aryl iodides and bromides, enabling straightforward access to halogenated aryl ketones.