Total Synthesis of Lamellarin D Trimethyl Ether, Lamellarin D, and Lamellarin H
作者:Dhanaji M. Lade、Amit B. Pawar、Prathama S. Mainkar、Srivari Chandrasekhar
DOI:10.1021/acs.joc.7b00636
日期:2017.5.5
three different lamellarins have been accomplished using a Ru(II)-catalyzed (3 + 2) annulation strategy to construct the central pyrrole ring. The striking features of this synthesis are the use of PEG-400 as a green solvent for the (3 + 2) annulation reaction and multiple catalytic reactions with excellent overall yield. The present route also enables the synthesis of various lamellarin analogues devoid
A General Method for the Synthesis of N-Unsubstituted 3,4-Diarylpyrrole-2,5-dicarboxylates
作者:Masatomo Iwao、Tsutomu Fukuda、Yukie Hayashida
DOI:10.3987/com-08-s(f)89
日期:——
A general method for the synthesis of N-unsubstituted 3,4-diarylpyrrole-2,5-dicarboxylates (3) has been developed. The key reactions involved are the Hinsberg-type synthesis of dimethyl N-benzyl-3,4-dihydroxypyrrole-2,5-dicarboxylate (6) followed by palladium-catalyzed Suzuki-Miyaura coupling of its bis-triflate derivative (7). The N-benzyl protecting group of the resulting 3,4-diarylpyrrole-2,5-dicarboxylates (8) is cleanly removed under hydrogenolytic or solvolytic conditions.
Modular Synthesis of Lamellarins via Regioselective Assembly of 3,4,5-Differentially Arylated Pyrrole-2-carboxylates
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.