title: One-pot synthesis of 1,3,5-tribenzoylbenzenes by three consecutive Michael addition reactions of 1-phenyl-2-propyn-1-ones in pressurized hot water in the absence of added catalysts.
abstract: Cyclotrimerization of 1-phenyl-2-propyn-1-one in pressurized hot water gave 1,3,5-tribenzoylbenzene in one pot in 65 % yield after 7 min at 200 °C, or in 74 % yield after 60 min at 150 °C. The reaction did not take place in the absence of water, and added base promoted the reaction at 250 °C, suggesting a mechanism of three-consecutive Michael addition reactions. The reaction rates increased with temperature, but the yield of 1,3,5-tribenzoylbenzene decreased at the expense of formation of acetophenone as a side product at higher temperatures. p-Methyl and p-chloro-substituents on the phenyl ring retarded and enhanced the reaction, respectively. A mechanism involving the enol of benzoylacetaldehyde at a branching point of the pathway leading to 1,3,5-tribenzoylbenzene and acetophenone was suggested.
authors.affiliation: College of Industrial Technology, Nihon University, 1-2-1 Izumi-cho, Narashino, Chiba 275-8575, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Tanaka
authors.forename: Kazuya
authors.initials: K
authors.lastname: Nakamura
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Iwado
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sato
authors.forename: Masaki
authors.initials: M
authors.lastname: Okada
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Sue
authors.forename: Hiizu
authors.initials: H
authors.lastname: Iwamura
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Hiaki