Pyridinium Hydrobromide Perbromide Catalyzed Organic Reaction Under Green Condition

Two part of this thesis has focused on studied the synthesis of bisindolymethanes and acetals catalyzed by pyridinium tribromide.In partâ… , electrophilic substitution reaction of indoles with aldehydes and ketones catalyzed by pyridinium tribromide (PTB) in water were studied in detailed. A method that pyridinium hydrobromide perbromide can efficiently catalyze the electrophilic substitution reaction of a variety of indoles with aldehydes and ketones in water to give bisindolymethanes was developed. Under the optimized reaction conditions good to excelent yelds of the corresponding bisindolymethanes were obtained with 15 mol% catalyst of PTB. A wide spectrum of aldehydes and ketones can react with indoles under mild conditions in a short time. The use of this inexpensive and easily available catalyst under essentially mild reaction conditions, clean and easy work-up conditions makes this protocol practical and economically attractive.In partâ…¡,The acetalization of various aldehydes with alcohols using PTB as the catalyst was studied. The results showed that PTB was an efficient catalyst for the acetalization with high conversion under mild conditions. The corresponding aldehyde acetals were obtained in almost quantitative yields when alcohols were treated with aromatic aldehydes bearing an electron-withdrawing substituent such as a nitro group.