An orthometallated 1-naphthylketone has been generated on osmium by coupling of γ-hydroxyalkynyl and diphenylallenylidene ligands. Treatment of Os{C≡C–C(OH)Ph2}2(═C═C═CPh2){κ3-P,O,P-[xant(PiPr2)2]}(1) with HBF4 leads to [Os{κ2-O,C-[O═C(CHPh2)-naphthyl-Ph]}(≡C–CH═CPh2){κ3-P,O,P-[xant(PiPr2)2]}](BF4)2 (2), which gives [Os{κ2-O,C-[O═C(CHPh2)-naphthyl-Ph]}(═C═C═CPh2){κ3-P,O,P-[xant(PiPr2)2]}]BF4 (3) by deprotonation with (piperidinomethyl)polystyrene. The formation of the ketone of 2 and 3 is an HF-catalyzed process. The H+ and F– fragments of HF are introduced sequentially with two different HBF4 molecules. The first molecule delivers H+, while the second provides F–. The proton from the first molecule adds to the Cβ atom of the diphenylallenylidene ligand of 1 to form [Os{C≡C–C(OH)Ph2}2(≡C–CH═CPh2){κ3-P,O,P-[xant(PiPr2)2]}]BF4 (4). The hydroxide group from a γ-hydroxyalkynyl of 4 is removed with the proton of the second HBF4 molecule, whereas the osmium center abstracts a fluoride of [BF4]−, to give [OsF{═C[−C≡C–C(OH)Ph2]–CH═CPh2}(═C═C═CPh2){κ3-P,O,P-[xant(PiPr2)2]}]BF4 (5). Once both fragments of HF are strategically located, the alkenyl-(γ-hydroxyalkynyl)alkylidene ligand experiences a Rupe-type rearrangement intercepted by a Diels–Alder cycloaddition, in two steps. A dehydration intercepted by Diels–Alder cycloaddition initially occurs, which affords the fluoroalkenylnaphthyl derivative [Os{κ2-F,C-[FC(═CPh2)-naphthyl-Ph]}(═C═C═CPh2){κ3-P,O,P-[xant(PiPr2)2]}]BF4 (7). The subsequent reaction of the latter with water yields the orthometallated 1-naphthylketone of 3, releasing HF. The protonation of 3 with HBF4 leads to 2.

Financial support from the MICIN/AEI/10.13039/501100011033 (PID2020-115286GB-I00 and RED2022-134287-T), Gobierno de Aragón (E06_20R and LMP23_21), FEDER, and the European Social Fund is acknowledged.

Peer reviewed