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Paper | Regular issue | Vol 92, No. 9, 2016, pp.1643-1653
Published online, 26th July, 2016
DOI: 10.3987/COM-16-13514
Synthesis of 3-Hydroxy-1,3-dihydro-2H-pyrrolo[2,3-b]-, -[2,3-c]-, or -[3,2-c]pyridin-2-ones from the Respective N-Pyridinylpivalamides and α-Keto Esters

Kazuhiro Kobayashi,* Risa Kosuna, and Yuuki Chikazawa

*Division of Applied Chemistry, Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan

Abstract

A convenient synthesis of the title compounds utilizing the reaction of the dilithium compounds, generated in situ by the reaction between N-(pyridin-2-, -3-, or -4-yl)pivalamides and two equivalents of butyllithium in THF, with α-keto esters is described. Thus, N-(3-lithiopyridin-2-yl)pivalamide reacts smoothly leading to the formation of the corresponding α-hydroxy esters. These undergo deprotective cyclization in refluxing hydrochloric acid to afford 3-substituted 3-hydroxy-1,3-dihydro-2H-pyrrolo[2,3-b]pyridin-2-ones. Similarly, starting from N-(pyridin-3- or -4-yl)pivalamides, the corresponding 3-dihydro-2H-pyrrolo[2,3-c]- or -[3,2-c]pyridin-2-one derivatives, respectively, can be prepared.