Method for the production of 2- coumarone and substituted 2-coumarones

摘要

Preparation of (substituted) 2-coumarone (I) comprises reacting cyclohexanone (II) with carboxyl-containing acylating agent (III) to methyl 2-(2-oxo-cyclohexyl)-2-hydroxy-acetate (IV) and optional dehydration to a mixture (V) of methyl 2-oxo-cyclohexylidene-acetate and the enol-lactone of the acid; or direct conversion of (I) to (V); and catalytic gas phase dehydrogenation of (IV) or (V) to (I). Preparation of an optionally substituted 2-coumarone (I) comprises: (a1) reacting a (substituted) cyclohexanone of formula (II) with a carboxyl-containing acylating agent of formula (III) to a (substituted) methyl 2-(2-oxo-cyclohexyl)-2-hydroxy-acetate (IV); and either (b1) direct catalytic gas phase dehydrogenation of (IV) to (I); or (b2) dehydration to a mixture (V) of (substituted) methyl 2-oxo-cyclohexylidene-acetate (Va) and the enol-lactone of the (substituted) 2-oxo-cyclohexylidene-acetic acid (Vb) by azeotropic distillation under basic conditions or using a strong acid or strongly acid ion exchanger, followed by catalytic gas phase dehydrogenation to (I); or (a2) direct reaction to (V) under acid or basic conditions, followed by catalytic gas phase dehydrogenation to (I): R = (H or 1-3 carbon (C) alkyl or alkoxy; R1, R2 = H or 1-3 C alkyl; and R3 = 1-3 C alkyl. An Independent claim is also included for the preparation of (IV) by acylating (II) with (III), optionally followed by conversion of (IV) to (I) as above.