%0 Journal Article
%T A Green, Expeditious, One-Pot Synthesis of 3, 4-Dihydropyrimidin-2(1H)-ones Using a Mixture of Phosphorus Pentoxide-Methanesulfonic Acid at Ambient Temperature
%A Amulrao Borse
%A Mahesh Patil
%A Nilesh Patil
%A Rohan Shinde
%J ISRN Organic Chemistry
%D 2012
%R 10.5402/2012/415645
%X An expeditious, one-pot method for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones using a mixture of phosphorus pentoxide-methanesulfonic acid (Eaton¡¯s reagent) at room temperature under solvent-free conditions is described. The salient features of this method include short reaction time, green aspects, high yields, and simple procedure. 1. Introduction The widespread interest in 3,4-dihydropyrimidin-2(1H)-ones, Biginelli compounds, has resulted in enormous efforts towards the synthesis of this biologically important moiety. Several methods have been developed for the synthesis of these compounds, but most of these protocols involve expensive reagents, strong acid catalysts, solvents, of prolonged reaction time and even then provide the products in unsatisfactory yields. With the current global awareness of developing environmentally friendly technologies, it is a need to perform a reaction in neat and nonhazardous conditions for providing a green approach towards organic synthesis [1]. Therefore, it was decided to develop an efficient method for the synthesis of Biginelli compounds. In this communication, we report a straightforward and simple procedures for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones using a mixture of phosphorus pentoxide-methanesulfonic acid (Eaton¡¯s reagent). Eaton¡¯s reagent (1£¿:£¿10 phosphorus pentoxide in methanesulfonic acid) is an inexpensive and commercially available substance synthesized by Eaton in 1973 and found to be a good alternative to polyphosphoric acid which enables the drawbacks of many traditional catalysts to be overcome, because it has a much lower viscosity, it is easier to handle, and no complex separation procedures need to be employed [2]. Many processes that employ a mixture of P2O5/MeSO3H are not only more economical, but also they are more environmentally friendly and offer a number of distinct advantages such as safe in industrial scale, no additional solvent required, chlorine-free, rapid reactions, and high-purity products with excellent yields. The distinctive physical and chemical properties of Eaton¡¯s reagent make it a very useful substance in many different reactions with different applications. The mixture of P2O5/MeSO3H is particularly effective for ring closures. McGarry and Detty successfully used this reagent in cycloacylation reactions for producing chromones and flavones [3]; recently, Zewge and coworkers used Eaton¡¯s reagent to promote the cyclization of aniline derivatives to produce 4-quinolones [4]. P2O5/MeSO3H offers a simple means of producing poly(benzimidazoles) from
%U http://www.hindawi.com/journals/isrn.organic.chemistry/2012/415645/