A review of the syntheses of flavanones, thioflavanones, and azaflavanones from 2'‐substituted chalcones. (16th November 2021)

• Record Type: Journal Article
• Authors: In Lee, Jae
• Is Part Of: Bulletin of the Korean Chemical Society. Volume 43:Number 1(2022)
• Page Start: 117
• Page End: 128
• Publication Date: 2021-11-16
• Subjects: 1, 4‐addition -- 2′‐substituted chalcones -- cyclization -- flavanones -- substitution; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/bkcs.12439
• Languages: English
• ISSNs: 0253-2964

Abstract

Abstract: Flavanones have been prepared by the cyclization of 2'‐hydroxychalcones using acidic reagents, such as H2 SO4, HX, CF3 COOH, CH3 SO3 H, KF‐celite, or SiO2 . Treatment of 2'‐hydroxychalcones with bases, such as LiOH, KOH, NaOAc, K2 CO3, pyridine, Et3 N, or N ‐methylimidazole afforded flavanones. The conversion of 2'‐hydroxychalcones to flavanones has been conducted using Co(salpr), K3 Fe(CN)6, CuO, or Ni(Tfacac)2 . Thioflavanones have been prepared by deprotecting and cyclizing S ‐protected chalcones using AgNO3, HBr, CF3 COOH, or NaOH and by adding NaSH or KCS2 OEt to 2'‐halochalcones and subsequent substitution. Azaflavanones have been prepared by cyclizing 2'‐aminochalcones using acidic reagents, such as H3 PO4, HCl, silica chloride, or K‐10 clay. Furthermore, treatment of 2'‐aminochalcones with Lewis acids, such as ZnCl2, SbCl3, Yb(OTf)3, InCl3, TaBr5, or CeCl3 afforded azaflavanones, and chiral azaflavanones were prepared by cyclizing 2'‐aminochalcones in the presence of per‐6‐ABCD, chiral amine, BINOL‐phosphoric acid, or thiourea catalyst. Abstract : Typical methods for the preparation of flavanones, thioflavanones, and azaflavanones from 2'‐substituted chalcones.