Phosphorus tribromide → 1-(3-Bromopropyl)-3-methoxybenzene

Participants

Reaction Steps

Referring now to FIG. 1, wherein the compounds are assigned Roman numerals for identification schematically, the sequence of reactions involved in the synthesis of a specific embodiment, namely, 13β,17α-diethyl-17β-hydroxygon-4-en-3-one, is illustrated. 3-(m-Methoxyphenyl)propanol (I) is heated with phosphorus tribromide in benzene after dropwise addition in the cold to form 3-(m-methoxyphenyl)propyl bromide (II). This halogen compound (II) dissolved in tetrahydrofuran is condensed with sodium acetylide in liquid ammonia to obtain 5-(m-methoxyphenyl)-1-pentyne (III). Compound III is allowed to stand under nitrogen with water, 30% formalin, acetic acid, diethylamine, dioxan, and cuprous chloride at 70° C for about 12 hours, whereby there is obtained 1-diethylamino-6-(m-methoxyphenyl)-2-hexyne (IV), which is in turn hydrated in the presence of a mercury salt and sulfuric acid to form 1-diethylamino-6-(m-methoxyphenyl)-3-hexanone (V). The ketamine (V) may eliminate diethylamine on distillation to give the vinyl ketone 6-(m-methoxyphenyl)-1-hexen-3-one (VI). Either the ketamine (V) or the ketone (VI), or mixtures thereof, is then reacted with 2-ethyl-1,3-cyclopentanedione (VII) under Michael condensation conditions, e.g. refluxing in methanolic potassium hydroxide to form 2-ethyl-2-[6-(m-methoxyphenyl)-3-oxohexyl]-1,3-cyclopentanedione (VIII).

Provenance & Evidence