PROCESS FOR PREPARING OXOHYDROCHROMENES Russian patent published in 1995 - IPC

FIELD: chemistry of heterocyclic substances, more particularly a process for preparing oxohydrochromenes. SUBSTANCE: the product: oxohydrochromenes of the general formula 1 wherein R₁ is a hydrogen atom or C₁-C₆-alkyl; R₂ and R₃ are phenyl which may be substituted by an C₁-C₆ alkoxy group. Reagent 1: 2-(3-oxopropyl)-cyclohexane-1,3-dione. Reaction conditions: the reagent is cyclized at the boiling point at a pH of 14.0-18. in the presence of a mixture of sulfuric acid and glacial acetic acids (in the following amounts (wt 5): 14 reagent 1; 84.5-85 glacial acetic acid, and 0.8-1.5 sulfuric acid. These factors make the process simpler and the yield of the desired product increases up to 57.2-70% The structural formula 1: . EFFECT: more efficient preparation process.