Mukonine

A Palladium-Catalyzed Ullmann Cross-Coupling/Reductive Cyclization Route to the Carbazole Natural Products 3-Methyl-9H-carbazole, Glycoborine, Glycozoline, Clauszoline K, Mukonine, and Karapinchamine A.[Pubmed:28225623]

J Org Chem. 2017 Apr 21;82(8):4148-4159.

The title natural products 2-7 have been prepared by reductive cyclization of the relevant 2-arylcyclohex-2-en-1-one (e.g. 20) to the corresponding tetrahydrocarbazole and dehydrogenation (aromatization) of this to give the target carbazole (e.g. 4). Compounds such as 20 were prepared using a palladium-catalyzed Ullmann cross-coupling reaction between the appropriate 2-iodocyclohex-2-en-1-one and o-halonitrobenzene.

Intramolecular Pd(II)-catalyzed oxidative biaryl synthesis under air: reaction development and scope.[Pubmed:18543991]

J Org Chem. 2008 Jul 4;73(13):5022-8.

New reaction conditions for intramolecular palladium(II)-catalyzed oxidative carbon-carbon bond formation under air are described. The use of pivalic acid as the reaction solvent, instead of acetic acid, results in greater reproducibility, higher yields, and broader scope. This includes the use of electron-rich diarylamines as illustrated in the synthesis of three naturally occurring carbazole products: Murrayafoline A, Mukonine, and Clausenine. A variety of side products have also been isolated, casting light on competing reaction pathways and revealing new reactivity with palladium(II) catalysis.

Synthesis of Carbazoles and Dibenzofurans via Cross-Coupling of o-Iodoanilines and o-Iodophenols with Silylaryl Triflates and Subsequent Pd-Catalyzed Cyclization.[Pubmed:18180808]

Tetrahedron. 2007 Jan 8;63(2):347-355.

An efficient route to a variety of carbazoles and dibenzofurans has been developed. It involves the reaction of o-iodoanilines or o-iodophenols with silylaryl triflates in the presence of CsF to afford the N- or O-arylated products, which are subsequently cyclized using a Pd catalyst to carbazoles and dibenzofurans in good to excellent yields. By using this methodology, the carbazole alkaloid Mukonine has been synthesized in 76% overall yield in three steps.

Synthesis and antiproliferative activity of clausine E, mukonine, and koenoline bioisosteres.[Pubmed:17548198]

Bioorg Med Chem. 2007 Aug 15;15(16):5615-9.

Aza-analogues of clausine E, Mukonine and koenoline were prepared from 1-(benzenesulfonyl)-1H-pyrrolo[2,3-b]pyridine-3-carboxaldehyde and their antiproliferative activity was evaluated against miscellaneous cancer cell lines and compared to those obtained with clausine E and Mukonine.

Double N-arylation of primary amines: carbazole synthesis from 2,2'-biphenyldiols.[Pubmed:15651780]

J Org Chem. 2005 Jan 21;70(2):413-9.

The double N-arylation of primary amines with 2,2'-biphenylylene ditriflates was investigated for the synthesis of multisubstituted carbazoles. Palladium complexes supported by 2-dicyclohexylphosphino-2'-methylbiphenyl or Xantphos [4,5-bis(diphenylphosphino)-9,9-dimethylxanthene] were found to be efficient catalysts for the reaction. The catalysts allow the use of anilines with an electron-donating or electron-withdrawing substituent and multisubstituted 2,2'-biphenylylene ditriflates as substrates. Ammonia equivalents, such as O-tert-butyl carbamate, are also employable as a nitrogen source to give the N-protected carbazoles which can easily give the corresponding N-unsubstituted carbazoles after deprotection. By using this methodology, a carbazole alkaloid, Mukonine, is synthesized in 40% yield for five steps, in comparable efficiency to the recent precedents.

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