LiClO4-Catalyzed One-Pot Synthesis of Dihydropyrimidinones: An Improved Protocol for Biginelli Reaction

Abstract

Lithium perchlorate efficiently catalyzes the three-component condensation reaction of aldehyde, b-keto ester and urea in refluxing acetonitrile to afford the corresponding dihydropyrimidinones in high yields under neutral conditions. LiOTf is also found to be an efficient catalyst for the synthesis of dihydropyrimidinones from aldehyde, b-keto ester and urea.

Magnesium Chloride Hexahydrate Catalyzed One‐Pot Synthesis of 3,4‐Dihydropyrimidin‐2‐(1H)ones Under Solvent‐Free Conditions

“…[4] This method suffers from low yields, especially in the cases of aliphatic and some substituted aromatic aldehydes. Recently, many improved procedures were reported for the preparation of DHPMs using Bi(OTf ) 3 , [5] ZrCl 4 , [6] InCl 3 , [7] LiClO 4 , [8] FeCl 3 . 6H 2 O or NiCl 2 .…”

Lithium Perchlorate/Diethyl Ether (LPDE)

“…Anhydrous LiClO 4 and diethyl ether were cooled separately in an ice bath under a nitrogen atmosphere, and then the ice cold ether was added very slowly to LiClO 4 via syringe. The dissolution was highly exothermic.…”

“…It promotes organic reactions such as aldol condensation, cycloaddition, and sigmatropic rearrangements. Among the many organic reactions mediated by LPDE, one-pot three component aminoalkylation of aldehydes, 2 Mannich reaction, 3 Biginelli reaction 4 are worth to notice. The three component condensation reaction of aldehydes and amines with various nucleophiles also takes place in this medium and leads to the facile synthesis of a-aminonitriles, 5 a-aminophosphonates, 6 a-cyanohydroxylamines, 7 N-trimethysilyloxya-aminophosphonates, 8 and a-hydrazinophosphonates.…”

A One-pot Multi-component Synthesis of Dihydropyrimidinone/Thione and Dihydropyridine Derivatives via Biginelli and Hantzsch Condensations using t-BuOK as a Catalyst Under Solvent-free Conditions

“…To enhance the efficiency of the Biginelli reaction, various catalysts and reaction conditions have been studied including classical conditions with ultrasound [23] [36], PhB(OH) 2 [37] and CuI [38]. The catalytic effect of metal cations is even more pronounced with methods based on metal salts with non-nucleophilic anions such as LiClO 4 [39], CuSO 4 .5H 2 O [40], Cu(OTf) 2 [41], Al(HSO 4 ) 3 [42], trimethylsilyl triflate [43], which allow the preparation of DHPMs in good to high yields. The use of BF 3 .OEt 2 [44], polyphosphate ester [45], (NH 4 ) 2 CO 3 [46], NaCl [47] and {Fe 2 CuO} clusters [48] has also been described.…”