Process for preparing substituted 1, 4 - quinone methides

摘要

Preparing (M1) a substituted 1,4-quinone methide (I) involves reacting a 3,5-disubstituted 4-hydroxybenzaldehyde (II) with an orthoformate (III) and an alcohol and/or thioalcohol ((thio)alcohol) (IV) in the presence of at least one catalyst e.g. free or solid-phase-bound organic sulfonic acid, sulfuric acid, a hydrogen sulfate, an organic or inorganic phosphorus acid, fuming nitric acid and boric acid, to obtain a (thio)acetal; and eliminating the alcohol or thiol from the obtained (thio)acetal to form substituted 1,4-quinone methide (I). Preparing (M1) a substituted 1,4-quinone methide of formula (I) involves reacting a 3,5-disubstituted 4-hydroxybenzaldehyde of formula (II) with an orthoformate of formula R 6O-CH(OR 4)-OR 5(III) and an alcohol and/or thioalcohol ((thio)alcohol) of formula R 3-X-H (IV) in the presence of a at least one catalyst selected from a free or solid-phase-bound organic sulfonic acid, sulfuric acid, a hydrogensulfate, an organic or inorganic phosphorus acid, a dihydrogen or hydrogen salt of an organic or inorganic phosphorous acid, fuming nitric acid and boric acid, to obtain a (thio)acetal; and eliminating the alcohol or thiol from the obtained (thio)acetal to form the substituted 1,4-quinone methide (I). R 1and R 2 : 1-15C alkyl, 3-15C cycloalkyl or 6-14C aryl (all optionally substituted) or H; R 7 : 1-15C alkyl, 3-15C cycloalkyl or 6-14C aryl (all optionally substituted); X : O or S; R 4, R 5and R 6 : 1-15C alkyl, 3-15C cycloalkyl or 6-14C aryl (all optionally substituted); R 3 : 1-15C alkyl, 3-15C cycloalkyl or 6-14C aryl (all optionally substituted). Independent claims are included for following: (1) preparing a substituted 1,4-quinone methide of formula (V) involving reacting a substituted 1,4-quinone methide (I) (R 7is unsubstituted 1-2C alkyl and X is O) with an alcohol or thioalcohol of formula R 8-SH (VI) to form substituted 1,4-quinone methide of formula (V); and (2) preparing (M2) a 3,5-disubstituted 4-hydroxybenzaldehyde (II) involving reacting a 2,6-disubstituted phenol of formula (VII) with urotropin in a solvent mixture consisting of glacial acetic acid and water at temperature of at least 2[deg] C below a reflux temperature of the reaction mixture over the entire reaction time. R 8 : 3-15C alkyl, 3-15C cycloalkyl or 6-14C aryl (all optionally substituted). [Image] [Image].