title: Modular synthesis of lamellarins via regioselective assembly of 3,4,5-differentially arylated pyrrole-2-carboxylates.
abstract: A modular synthesis of lamellarins via 3,4,5-differentially arylated pyrrole-2-carboxylate intermediates has been developed. The key reactions employed are Br-Li exchange-methoxycarbonylation of 2,5-dibromo-1-(tert-butoxycarbonyl)-1H-pyrrole (1) followed by palladium-catalyzed iterative Suzuki-Miyaura coupling of the pyrrole core. The 3,4,5-triarylpyrrole 4 thus synthesized was readily converted to 5,6-saturated lamellarin L (2) and 5,6-unsaturated lamellarin N (3) via lactonization followed by annulation of the pyrrole nitrogen and lateral aromatic ring at C5 using 2-bromoethyl phenyl sulfide or bromoacetaldehyde dimethyl acetal as two-carbon homologation agents. In principle, this strategy allows the production of diverse lamellarins in short steps with high yields using readily accessible arylboronic acids as aromatic modules.
authors.affiliation: Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University , 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Komatsubara
authors.forename: Teppei
authors.initials: T
authors.lastname: Umeki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Fukuda
authors.forename: Masatomo
authors.initials: M
authors.lastname: Iwao
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; C002986:2-pyrrolecarboxylic acid; D011392:Proline