An efficient and practical synthesis of β-hydroxyl ketones catalysed by trisodium phosphate under ultrasound

Abstract

The aldol condensation is one of the most important carboncarbon bond-forming reactions in organic chemistry. 1 Over the past several years, research in the area of aldol type addition reactions has dramatically increased. This is due, in part, to the large number of important natural products containing the β-hydroxyl carbonyl unit.Aldol reaction have been classically conducted in the presence of a strong base or acid. 2 However, under such conditions, the synthesis of the desired aldol product is plagued by the formation of the concomitant α,β-unaturated ketone, Michael addition to the formed enone, and so on. To overcome these problems, various Lewis acids 3 or bases 4 have been employed as alternative catalysts, but in most cases the ketones need to be modified as silyl enol ethers, ketene silyl acetals, etc. Meanwhile, aldol reactions can also be carried out in the presence of phase-transfer catalysts such as TBAF 5 and calix [6] arene derivatives 6 or without catalyst 7 , but the ketones also need to be modified. In recent years, proline-catalysed aldol reactions in aqueous micelles have been reported. 8 In addition, potassium phosphate was found to catalyse the condensation of nitroalkanes with various aliphatic and aromatic aldehydes to form nitroaldols. Most recently, Na 2 CO 3 has been used to promote aldol reactions of unmodified ketones with reactive aldehydes in pure water. 10 However, in spite of their potential utility, some of the reported methods suffer from drawbacks such as longer reaction times and lower yields.

3-(2,6-Dichlorophenyl)-3-hydroxy-1-phenylpropan-1-one

“…The title compound, (I), C 15 H 12 Cl 2 O 2 , was obtained in high yield in the usual manner (Li et al, 2004) from the aldol reaction of 2,6dichlorobenzaldehyde and acetophenone. Under the same conditions chalcones were the principal products when using 2-chlorobenzaldehyde or 2,4-dichlorobenzaldehyde (House et al, 1973;Mukaiyama et al, 1974;Sakthivel et al, 2001).…”

Polymerization of N-phenylmaleimide Using Different Catalysts

“…One significant negative is that they eventually end up being neutralized at the end of the reaction, making the catalyst unusable and challenging to recover a pure product. Herein, we sought to look for an alternative way to overcome this major problem (Li, 2004).…”