Palladium catalyzed/silver tuned selective mono-/tetra-acetoxylation of o-carboranes via B–H activation

Abstract

A palladium catalyzed/silver tuned selective mono- and tetra-acetoxylation of o-carboranes has been developed, and a series of mono- and tetra-acetoxylated o-carboranes decorated with active groups have been synthesized with moderate to good yields as well as excellent selectivity. A mechanism involving electrophilic palladation and cyclopalladation of the B-H bond was proposed.

Transition‐Metal‐Catalyzed Selective Cage B−H Functionalization of o‐Carboranes

“…In a similar manner, the Cao group developed a Pd‐catalyzed cage B(8,9,10,12)‐tetraacetoxylation of o ‐carboranes using an excess amount of PhI(OAc) 2 as the acetoxylation reagent and oxidant (Scheme ) . The reaction mechanism is similar to that of tetrafluorination as shown in Scheme .…”

Palladium‐Catalyzed Selective Mono‐Chlorination of o‐Carboranes: Changing the Concept of FeCl3 from Lewis Acid to Chlorine Source in Carboranes

“…FeCl 3 , a generalist regent possessed Lewis acidity, oxidizability as well as transition metal characteristics, which has displayed extraordinary catalytic performance in construction of C‐C and C‐N bonds . Recently, we have reported a silver tuned selective mono‐/tetra‐acetoxylation of o ‐carboranes . In this work, we found the coordination effect of Lewis acid with B‐H bond could be weakened by acetic anhydride.…”

Electrooxidative o-carborane chalcogenations without directing groups: cage activation by copper catalysis at room temperature

“… 5 As a consequence, considerable progress has been witnessed in transition metal-catalyzed regioselective cage B–H functionalization of o -carboranes 6 and different functional motifs have been incorporated into the cage boron vertices. 7–10 However, progress in this research arena continues to be considerably limited by the shortage of robust and efficient methods to access carborane-functionalized molecules. While C–S bonds are important structural motifs in various biologically active molecules and functional materials, 11 strategies for the assembly of chalcogen-substituted carboranes continue to be scarce.…”