Nickel‐Catalyzed Regioselective [2+2+2] Cycloaddition of Carboryne with Alkynes

Three‐Component [2+2+2] Cycloaddition of Carboryne, Unactivated Alkene, and Alkyne via Zirconacyclopentane Mediated by Nickel: One‐Pot Synthesis of Dihydrobenzocarboranes

“…[7] For example, nickelacyclopentene incorporating a carboranyl moiety is a reactive intermediate toward alkynes, [5,8] whereas the zirconacyclopentene analogue is inert.…”

“…Our previous work shows that the nature of transition metals dominates the reactivity pattern of the corresponding metallacycles. [7] For example, nickelacyclopentene incorporating a carboranyl moiety is a reactive intermediate toward alkynes, [5,8] whereas the zirconacyclopentene analogue is inert. [9] We have recently found that the zirconacyclopentane incorporating a carboranyl unit is also very thermally stable and inert toward alkenes and alkynes, which is significantly different from those zirconacyclopentanes without carboranyl groups.…”

“…In DME, both selectivity and yield decreased a little (Table 1, entry 5). Phosphine-coordinated nickel complexes all gave the product in yields higher than 91 % but with poor selectivity ( Table 1, entries [6][7][8][9][10][11].…”

A Domino Approach to the Enantioselective Total Syntheses of Blennolide C and Gonytolide C

“…With this in mind, we speculated that 1,3‐dehydro‐ o ‐carborane (Figure 1), featuring a cage compound having CB bonds with multiple bonding characters, would be a reactive intermediate for simultaneous functionalization of both cage carbon and boron vertices. Such a species might be generated in a similar manner to that of o ‐carboryne, which can be produced from 1‐X‐2‐Li‐ o ‐C 2 B 10 H 10 by LiX salt elimination (X=Br,2a I2c; Scheme ).…”

Three‐Component [2+2+2] Cycloaddition of Carboryne, Unactivated Alkene, and Alkyne via Zirconacyclopentane Mediated by Nickel: One‐Pot Synthesis of Dihydrobenzocarboranes

“…Our previous work shows that the nature of transition metals dominates the reactivity pattern of the corresponding metallacycles 7. For example, nickelacyclopentene incorporating a carboranyl moiety is a reactive intermediate toward alkynes,5, 8 whereas the zirconacyclopentene analogue is inert 9. We have recently found that the zirconacyclopentane incorporating a carboranyl unit is also very thermally stable and inert toward alkenes and alkynes, which is significantly different from those zirconacyclopentanes without carboranyl groups 10.…”