Synthesis of glycolurils and hydantoins by reaction of urea and 1, 2‐dicarbonyl compounds using etidronic acid as a “green catalyst”

Abstract

Most of the known methods for the synthesis of heterocyclic compounds have disadvantages, such as a long reaction time and aggressive conditions. We have developed a new, rather simple and efficient method for the synthesis of a number of glycoluryls and hydantoins in water using a etidronic acid (HEDP) as "Green catalyst." So, for the first time, the condensation reaction of ureas with 1, 2-dicarbonyl compounds was carried out in the presence of HEDP. Also based on NMR studies, a chemism of these reactions, which is stepwise, is proposed. It has been established that the optimal conditions for the synthesis of glycoluryls and hydantoins using HEDP are: temperature 80 C-90 C, 40-20 minutes, and the ratio of urea and HEDP is 1:1. In all cases, the remaining aqueous filtrate containing HEDP after the reaction can be reused for other cycles synthesis of glycoluril and other compounds, because HEDP is not converted during the reaction.

N-Nitrosation of Glycolurils Catalyzed by 1-Hydroxyethylidene-1,1-diphosphonic Acid

“…One of the advantages of the HEDP catalyst is that it is able to enhance the solubility of glycoluryl 1a [12], selectively destroying the crystal packing and thereby making substrate 1a readily available for reaction at the nitrogen atoms. However, the excess of HEDP leads to the formation of by-product hydantoin 3 (Scheme 3) [10][11][12], and this explains why we use as little as 2 equiv of HEDP.…”

“…The NMR analysis of the reaction fi ltrate (Scheme 1) (see Supplementary Information) showed that the reaction mixture contained, along with HEDP, hydantoin 3 [10][11][12] and N-nitrosohydantoin 4 (Scheme 3).…”

“…The absence of hydantoins in the reaction mixtures of glycoluryls 1b-1f is obviously explained by the fact that N-and C-substitutions in compounds 1b-1f make them less prone to destruction [10].…”

“…1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP) are known by its anticorrosive properties and used as a scale inhibitor in water circulation cooling systems of industrial plants and thermal power plants [9]. We earlier found that HEDP is capable of effi ciently catalyzing condensation [10,11] and N-acetylation reactions of glycoluryl 1a [12]. In view of the aforesaid, we set ourselves the task to explore the potential of HEDP as a catalyst in the synthesis of a series of N-nitroso derivatives of glycoluryls (Scheme 1).…”

A Complete Study of Synthesis of Glycoluril and Its Derivative by Using Different Greener Acids

“…The maximum reported yield till date is 62 %. [46] 1 H NMR (500 MHz, DMSO-d 6 ) δ 5.05, 2.82. 13 5) was prepared by dissolving urea and benzil in ethanol and stirring the mixture for 10 minutes.…”