Consecutive Palladium-catalyzed Reactions Research Articles

Synthesis of 7 H-indolo[2,3- c]quinolines: study of the Pd-catalyzed intramolecular arylation of 3-(2-bromophenylamino)quinolines under microwave irradiation

D-ring substituted 5-methyl-5 H-indolo[2,3- c]quinolines ( 4 ) have been synthesized in three steps starting from commercially available 3-bromoquinoline ( 5 ) and 2-bromoanilines ( 6 ). The methodology consists of two consecutive palladium-catalyzed reactions: a selective Buchwald–Hartwig amination followed by a regioselective intramolecular Heck-type reaction. The latter step has been investigated under microwave irradiation. Heating at 180 °C allows to seriously reduce the catalyst loading and get a full conversion to reaction product in 10 min. In addition, the former simplifies the purification.

Synthesis of the Benzo‐β‐Carboline Isoneocryptolepine: The Missing Indoloquinoline Isomer in the Alkaloid Series Cryptolepine, Neocryptolepine and Isocryptolepine.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of fused indoles by sequential palladium-catalyzed Heck reaction and N-heteroannulation

A route to 3,4-fused indoles via two consecutive palladium-catalyzed reactions; an intramolecular Heck reaction followed by a reductive N-heteroannulation is described. Using this route, a number of indoles have been prepared having a variety of ring sizes anchored to the 3- and 4-position of the indole nucleus. Furthermore, a number of functional groups, both carbon and heteroatom substituents can be introduced in (and on) the additional ring without any detrimental effects on the two reactions.

Synthesis of the benzo-β-carboline isoneocryptolepine: the missing indoloquinoline isomer in the alkaloid series cryptolepine, neocryptolepine and isocryptolepine

7 H-Indolo[2,3- c]quinoline has been synthesized in two steps via a new approach starting from commercially available 3-bromoquinoline and 2-bromoaniline. The new methodology consists of two consecutive palladium-catalyzed reactions: a selective Buchwald/Hartwig amination followed by an intramolecular Heck-type reaction. Alternatively, the same skeleton has also been prepared via the combination of a Suzuki arylation with an intramolecular nitrene insertion starting from 4-chloroquinoline and {2-[(2,2-dimethylpropanoyl)amino]phenyl}boronic acid. Selective methylation of 7 H-indolo[2,3- c]quinoline yielded 5-methyl-5 H-indolo[2,3- c]quinoline (Isoneocryptolepine) which is an interesting new lead compound in the search for new antiplasmodial drugs.

Synthesis of Isocryptolepine via a Pd‐Catalyzed “Amination—Arylation” Approach.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Isocryptolepinevia a Pd-Catalyzed ‘Amination-Arylation’ Approach

Isocryptolepine (cryptosanguinolentine) has been synthesized in three steps via a new approach starting from commercially available 4-chloroquinoline and 2-chloroaniline. The new methodology consists of two consecutive palladium-catalyzed reactions; a selective Buchwald-Hartwig amination followed by an intramolecular arylation reaction.

Palladium-catalyzed synthesis of fused indoles

A novel route to fused indoles via two consecutive palladium catalyzed reactions, an intramolecular Heck reaction followed by a reductive N-heteroannulation, has been developed. For example, reaction of 2-bromo-3-nitro-1-(3-butenyloxy)benzene with palladium diacetate, and tri(o-tolyl)phosphine in the presence of triethylamine gave a readily separable mixture (18:4:1) of dihydro-4-methylene-5-nitro-2 H-1-benzopyran, 4-methyl-5-nitro-2 H-1-benzopyran, and 4-methyl-5-nitro-4 H-1-benzopyran. Reaction of pure dihydro-4-methylene-5-nitro-2 H-1-benzopyran with palladium diacetate, 1,3-bis(diphenylphosphino)propane, and carbon monoxide in DMF (120 °C, 70 h, 60 psi CO) gave 3,5-dihydro-2 H-pyrano[4,3,2- cd]indole in 63% yield.