The Preparation of 2-(4-Oxo-4H-1-benzopyran-2-yl)-1-phenyl-ethanones by the Condensation/Cyclization of Dilithiated 1-Benzoylacetone with Lithiated Methyl Salicylates

Abstract

Dilithiated 1-benzoylacetone was prepared in excess lithium diisopropylamide and condensed with several lithiated methyl salicylates, followed by acid cyclization to 2-(4-oxo-4H-1-benzopyran-2-yl)-1-phenylethanones (2-phenacyl-chromones).

Notes

1-(2-hydroxy-4-methoxyphenyl)-5-phenyl-1,3,5-pentanetrione: Mp 187–89°C, 97% yield (ethanol): Anal. Calcd. for C₁₈H₁₆O₅: C, 69.22; H, 5.16. Found: C, 69.18; H, 5.04; IR (paraffin oil) 1679 shoulder of broad and intense peaks from 1609–1627 cm⁻¹; ¹H NMR (CDCl³)(see ref. 7, first sentence): δ 3.90 (s, OCH₃), 4.03 and 4.07 (s, -CH₂-), 6.42 and 6.52 (s, vinyl), 6.58–7.15 and 7.50–8.33 (m, ArH)