ChemInform Abstract: BENZO‐Γ‐PYRONES. PART VII. REACTION OF 3‐FORMYLCHROMONE WITH HYDROXYLAMINE

Novel data for the reaction of 3-cyano-(thio)chromones with N-nucleophiles

“…For the products of reaction of 3-formyl-or 3-cyanochromones with hydroxylamine besides the really formed chromone derivatives 32 and 33, the structures 34-37 has previously been proposed [18,[23][24][25]. These were not confirmed in the course of our repeated study [26].…”

New Potent SARS‐CoV 3C‐Like Protease Inhibitors Derived from Thieno[2,3‐d]‐pyrimidine Derivatives

“…“A” in Scheme ) undergo dehyrogenative cyclization to give the respective thienopyrimidinones 3a and 3b which can condense with hydrazine hydrate in the presence of phosphoryl chloride (POCl 3 ) to afford the corresponding hydrazinyl thienopyrimidines 4a and 4b (Scheme ). Amination of the γ‐pyrone ring to give 4b can occur via elimination of ammonia during approach of hydrazine molecule to the γ‐pyrone ring in the conventional manner . Structural assignments for 3a , b and 4a , b were supported by compatible elementary and spectroscopic analyses.…”

The first synthesis of 3‐hydroxy‐2‐(polyfluoroalkyl)chromones and their ammonium salts. 3‐hydroxychromone in the Mannich reaction

“…The most notable feature in the 1 H NMR spectra of 5 and 6 is the absence of a signal of the hydroxy group and the appearance of singlets at δ 4.04 and 2.41 ppm due to the MeO and MeCO groups. Previously, their non‐fluorinated analogs, 3‐methoxy‐, 3‐acetoxy‐, and 3‐hydroxy‐2‐methylchromones, were obtained by reaction of ω‐bromo‐2‐hydroxyacetophenone with acetic acid anhydride and sodium acetate [11]. The synthesis of 3‐hydroxy‐2‐methylchromone has been also achieved by oxidation of 2‐methylchroman‐4‐one with isoamyl nitrite [12].…”