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Paper | Special issue | Vol 97, No. 2, 2018, pp.916-930
Published online, 13th April, 2018
DOI: 10.3987/COM-18-S(T)68
Synthesis of 4,5-Disubstituted Pyrano[3,4-b]Pyrrol-7(1H)-ones via Sonogashira–Hagihara Cross-Coupling of N-Benzenesulfonyl-3-bromo-1H-pyrrole-2-carboxylate and Subsequent Iodine-mediated Cyclization

Tsutomu Fukuda,* Minoru Komure, Gen Onodera, Masanari Kimura, and Masatomo Iwao

*Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

Abstract

A method for the synthesis of 4,5-disubstituted pyrano[3,4-b]pyrrol-7-(1H)-ones has been developed in this study. The key reactions involved are the Sonogashira–Hagihara cross-coupling of methyl N-benzenesulfonyl-3-bromo-1H-pyrrole-2-carboxylate with terminal alkynes, followed by the iodine-mediated cyclization of 3-alkynylated N-benzenesulfonyl-1H-pyrrole-2-carboxylates. The thus-obtained 5-substituted 4-iodopyrano[3,4-b]pyrrol-7(1H)-ones could be converted to 4,5-disubstituted pyrano[3,4-b]pyrrol-7(1H)-ones via the Suzuki–Miyaura or Sonogashira–Hagihara cross-coupling reactions.