P-Toluenesulfonic acid as catalyst for

Reaction of butane-1,2,4-triol 28 1 with acetone and p-toluenesulfonic acid as catalyst for 62 h gives a thermodynamic mixture of isopropylidene derivatives consisting of the dioxolane 28.2 (90%) and the dioxane 283 (10%) in a com-... 

Use as acid catalyst. This acidic ester is superior to p-toluenesulfonic acid as catalyst for the preparation of 2, 3 -0-isopropyIidene (acetonide) and other ketal derivatives of ribonucleosides, for example of adenosine (3). A mixture of the nucleoside, acetone, the catalyst, and 2,2-dimethoxypropane (which serves as... 

Guzen et al. [110] developed a reaction of o-phenylenediamines (148) with diketone or ketones series (149) under ultrasound irradiation in the presence of p-toluenesulfonic acid as catalyst, for the synthesis of 1,5-benzodiazepines (150) (Scheme 39). The condensation reaction was conducted under soft conditions. Ethyl acetate, dichloromethane, dioxane, and 1,2-dimethoxyethane were tested as solvent mediums. Dichloromethane was the best solvent, providing good yields and shortening reaction times. 

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