method of preparation of ketones insaturees music

摘要

Higher alpha-substituted alpha, beta-unsaturated ketones R1-CH=CR2-COR3 (I) (where R1 is a sec. or tert. aliphatic hydrocarbyl opt. attached to a 5-7 membered ring, a phenyl gp. or a 5 or 6-membered heterocycle opt. substd. by inert substituents; R2 is 1-4C alkyl, cycloalkyl, or phenyl; R3 is as R1) are prepd. by an aldol condensation between R2CH2COR3 (II) and R1CHO (III) in the presence of boric acid or boric anhydride in the liquid phase at elevated temp. (I) are intermediates for herbicides and fungicides, (e.g. see US 3925408), and intermediates for hypoglycemic agents (e.g. see FR 2179559). Process gives good yields. A typical prod. is 1-phenyl-2,4-dimethyl-2-pentene-1-one. This was prepd. by heating propiophenone with isobutyraldehyde and boric anhydride at a pressure of 8 bars in an autoclave fitted with a stirrer and water separator. The yield was 91% of theory.