Expeditious Synthesis of the Marine Natural Products Prepolycitrin A and Polycitrins A and B through Heck Arylations

Abstract

New, efficient protocols for the syntheses of the marine natural products prepolycitrin A as well as polycitrins A and B were developed by employing the Heck–Matsuda arylation of maleic anhydride or dimethyl fumarate with aryldiazonium tetrafluoroborates. Both symmetrical and unsymmetrical 3,4‐diarylmaleic anhydrides were easily and effectively prepared. Efficient bromination reactions that employed tribromoisocyanuric acid provided access to the polycitrin family of compounds. Under microwave irradiation in the presence of tyramine, the corresponding maleimides were obtained in high yields from the brominated 3,4‐diarylmaleic anhydrides. This methodology provided for the concise synthesis of prepolycitrin A and the total syntheses of the marine alkaloids polycitrins A and B in overall yields of 37 and 47 % from maleic anhydride and dimethyl fumarate, respectively.

Benign Arylations of Dimethyl Itaconate via Heck–Matsuda Reaction Utilizing in‐Situ Generated Palladium on Aluminum Oxide

“…Stimulated by the work of Correia and co‐workers concerning the biarylation of acrylates and maleic anhydride, the iterative Heck–Matsuda couplings with itaconimides by B. Schmidt et al and encouraged by our studies regarding the β,β‐diarylation of acrylates and vinylphosphonates we decided to embark on the biarylation of dimethyl iatconate. In accordance with our previous reaction conditions regarding the β,β‐diarylation of acrylates with palladium on aluminum phosphate as catalyst, we converted several diazonium salts (2.2 equiv.)…”

Química Orgânica no Brasil: sua contribuição na síntese total de produtos naturais desde a fundação da SBQ

“…A evolução nesta área pode ser sentida nos exemplos mais recentes da preparação de alcaloides. A policitrina A, por exemplo, foi preparada de maneira muito eficiente através do uso de reação de Heck-Matsuda 20 , que emprega tetra-flúor-boratos de aril-diazônios como substrato, e é reação em estudo e desenvolvimento em nosso país e de extenso uso em sínteses totais 21 . A síntese da (+/-)-preussina também exemplifica a evolução da química no Brasil.…”

Carboxymethylcellulose‐supported palladium nanoparticles generated in situ from palladium(II) carboxymethylcellulose as an efficient and reusable catalyst for ligand‐ and base‐free Heck–Matsuda and Suzuki–Miyaura couplings

“…Recently, the progress of Heck–Matsuda and/or Suzuki–Miyaura reactions using aryldiazonium salts in the formation of carbon–carbon bonds has been reviewed. The traditional procedure for a Heck–Matsuda reaction generally involves catalysis using homogeneous palladium complexes including Pd(dba) 2 , 4b) Pd 2 (dba) 3 , Pd(OAc) 2 , PdCl 2 (CH 3 CN) 2 , Pd(TFA) 2 /chiral bisoxazoline ligand, palladacycle, Pd–NHC complex, Pd–phosphinous acid complexes, and so on. Pioneering studies of the Suzuki–Miyaura coupling of aryldiazonium salts with boronic acids were reported in 1996 by Genêt and co‐workers using Pd(OAc) 2 as catalyst .…”