The Aldol Reaction under High‐Intensity Ultrasound: A Novel Approach to an Old Reaction

Abstract

We have employed high-intensity ultrasound (HIU) to reinvestigate the aldol reaction (AR) in water. A number of aldols that under usual conditions would undergo elimination were isolated in acceptable to good yields. Within 15−30 min, acetophenone reacted with non-enolizable aldehydes to afford the aldol exclusively, while under conventional conditions (stirring or heating under reflux) the same compounds either failed to react or gave, after several hours, the enone, often in complex product mixtures. A library of polyols was obtained

Organic synthesis by Twin Screw Extrusion (TSE): continuous, scalable and solvent-free

“…Na2CO3 did not result in a complete reaction. Ultrasound irradiation has also been employed to carry out this reaction, 30 however this is still very difficult to scale up, supporting the use of extrusion for the large scale, continuous synthesis of a substituted 1,3 indandione (6).…”

Some condensations of methyl 4-acetylphenylcarbamate

“…Acetophenone and its derivatives are convenient starting materials for the synthesis of various compounds, including chalcones which can be converted into various heterocycles [1][2][3][4][5]. Chalcones and flavonoids generally exhibit versatile biological activity, in particular antituberculous [6].…”

Preparation of enantiomerically pure (R)- and (S)-3-amino-3-phenyl-1-propanol via resolution with immobilized penicillin G acylase

“…16 Compared to the above known methods, the method of preparing 2 by reaction of 1 with baker's yeast in a biphasic system is much simpler. Chiral 1,3-amino alcohols have potential applications both as pharmaceutically active compounds, agricultural chemicals, chiral intermediates, and chiral auxiliary agents.…”