Palladium/norbornene chemistry: an unexpected route to methanocarbazole derivatives via three Csp³–Csp²/Csp³–N/Csp²–N bond formations in a single synthetic sequence

Abstract

A Catellani reaction terminated by palladacycle amination leading to methanocarbazoles is reported. The outcome is the formation of three different Csp(3)-Csp(2)/Csp(3)-N/Csp(2)-N bonds through a Heck reaction/C-H activation/double amination cascade in one process.

DFT Study on the Mechanism of Palladium(0)-Catalyzed Reaction of Aryl Iodides, Norbornene, and Di-tert-butyldiaziridinone

“…For example, aryl halides can be replaced by diazonium salts, , tosylates, or acid chlorides to react with alkenes to form styrene compounds. On the other hand, in recent years, the Heck reaction has been employed in a tandem reaction with other reactants such as esters, , amides, , ketones, and halomethylsilanes, to construct new C–O, C–C, C–N, and C–Si bonds.…”

Palladium‐Catalyzed Three‐Component Reactions for the Synthesis of Norbornane‐Fused Indanes

“…Based on the above experimental results and previous reports, we proposed a tentative mechanism for the three‐component reactions. As shown in the Scheme , the initial oxidative addition of Pd 0 to aryl iodides, the subsequent stereoselective cis , exo insertion of norbornene, and intramolecular C−H bond activation afford arylnorbornyl palladacycle C . For the reaction with CH 2 Br 2 , the oxidative addition of CH 2 Br 2 to C forms intermediate D , which is then converted into palladacycle G via either intermediate E or carbene complex F .…”

“…[29] Based on the above experimental results and previous reports, [18,19,24] we proposed a tentative mechanism for the three-component reactions. As shown in the Scheme 3, the initial oxidative addition of Pd 0 to aryl iodides, the subsequent stereoselective cis, exo insertion of norbornene, and intramolecular CÀ H bond activation afford arylnorbornyl palladacycle C. [12] For the reaction with CH 2 Br 2 , the oxidative addition of CH 2 Br 2 to C forms intermediate D, which is then converted into palladacycle G via either intermediate E or carbene complex F. The reductive elimination of G generates desired product 4 and releases Pd II , which is then reduced to Pd 0 by reductants such as isopropanol or DMF. [16a,30] For the reaction with αdiazoesters, the insertion of 6 gives six-membered palladacycle intermediate H. Finally, the reductive elimination of H generates the final product 7 and release Pd 0 .…”

“…The major examples include the reactions with aryl halides and vinyl bromides . The C , C ‐palladacycles could also be aminated by diaziridinone and anilines to form norbornane‐fused indolines, and carbonylated by CO to yield norbornane‐fused cyclopentanones. In these reactions, arylnorbornyl palladacycles are difunctionalized to form norbornane‐containing polycyclic compounds.…”

Palladium/Norbornene Chemistry in the Synthesis of Polycyclic Indolines with Simple Nitrogen Sources

“…We also recently reported on a regioselective annulation reaction to provide N-arylindolines as a new outcome from the palladium-catalyzed reaction of iodoarenes, norbornene, and anilines. 16 Despite significant achievements, however, aliphatic amines remained challenging and more difficult than aromatic amines for this catalytic system. Aliphatic ureas also did not participate in this cascade.…”