Liyanage Perera E, Lee D. Synthesis of 4-Pyrones by Formal Hydration of 1,3-Diynones Promoted by 1,4-Addition of Piperidine.
Org Lett 2022;
24:7042-7046. [PMID:
36125167 DOI:
10.1021/acs.orglett.2c02914]
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Abstract
A new approach for the synthesis of 4-pyrones with broader substrate scope and functional group tolerance is described. The reaction proceeds via an initial 1,4-addition by piperidine, followed by nitrogen-assisted 6-endo-dig cyclization and hydrolysis. 1,3-Diynones with nonenolizable electron-withdrawing ketones and nonpropargylic H provide relatively high yields. For substrates with particular R2 substituents, 1,4- or 1,6-adducts were isolated, suggesting that steric and electronic factors of the R2 substituent should have a strong impact on the 6-endo-dig cyclization.
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