Ruthenium(III) Chloride-Catalyzed One-Pot Synthesis of 3,4-Dihydro­pyrimidin-2-(1H)-ones under Solvent-Free Conditions

Abstract

Ruthenium(III) chloride efficiently catalyzes the threecomponent Biginelli reaction of an aldehyde, a b-keto ester, and urea or thiourea under solvent-free conditions to afford the corresponding 3,4-dihydropyrimidine-2-(1H)-ones in excellent yields.

One-pot synthesis of Biginelli and Hantzsch products catalyzed by non-toxic ionic liquid (BMImSac) and structural determination of two products

“…The extreme puckering of the DHP ring would be increase the receptor binding and activity of the calcium channel drugs. The benzene ring is planar, the largest displacement observed being 0.007(2) for atom C (11), and the dihedral angel between the DHP ring and the benzene ring is 87.24 (9) • , close to the early reported 88.3(3) • [40]. The two ester groups are twisted …”

“…Since the Biginelli products, dihydropyrimidinone, can act as calcium channel blocker, antihypertensive agents and ␣-1a-antagonist [3], the Biginelli reaction [4], a one-pot but low yield (20-50%) condensation of ␤-dicarbonyl compounds with aldehydes and urea or thiourea in the presence of catalytic amount of acid, has increasingly attracted intense interest. In general, Lewis acids including BF 3 ·OEt 2 [5], CdCl 2 [6], NiCl 2 ·6H 2 O or FeCl 3 ·6H 2 O [7], In(OTf) 3 [8], InBr 3 [9], ZnCl 2 [10], RuCl 3 [11], ZrCl 4 [12], CeCl 3 ·7H 2 O [13], Mn(OAc) 3 ·2H 2 O [14], Yb(OTf) 3 [15], La(OTf) 3 [16], Sc(OTf) 3 [17] and other catalysts such as 12-tungstophosphoric acid [18], natural HEU type zeolite [19], silicagel supported sodium hydrogensulfate [20], N-bromosuccinimide [21] and iodine [22] can also catalyze the reaction. In addition, new methods, including microwave irradiation [23] and synthesis of solid phase [24], are also employed.…”

N-Propylcarbamothioyl benzamide complex of Bi(III) supported on superparamagnetic Fe3O4/SiO2 nanoparticles as a highly efficient and magnetically recoverable heterogeneous nanocatalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones (DHPMs) via the Biginelli reaction

“…Thus, due to their several applications in the biology and medical chemistry, considerable interest in this transformation has steadily increased in the past decade and several improved procedures have recently been reported using Mg(NO 3 ) 2-6H 2 O [12], Al(NO 3 ) 3 Á9H 2 O [13], ZrCl 4 [14], zeolites [15], silica sulfuric acid [16], BF 3 ÁOEt 2 [17], CuCl 2 Á2H 2 O [18], SbCl 3 [19], RuCl 3 [20], natural catalysts [21], glutamic acid [22], Bi(NO 3 ) 3 [23], Bi 2 (SO 4 ) 3 Á3H 2 O [24], eutectic salts [25], NH 4 Cl [26], SiCl 4 [27], Y(OAC) 3 [28], Cu(OTf) 2 [29], FeCl 3 [30], NH 2 SO 3 H [31], B(OH) 3 [32], acidic ionic liquid [tbmim]Cl 2 /AlCl 3 [33], Bi(NO 3 ) 3 Á5H 2 O-silicagel [34], HCl [35], ZnBr 2 [36], Er(OTf) 3 [37], Phytic acid [38], Fe 3 O 4 MWCNT nanocomposite [39] and Fe 3 O 4 supported Brønsted acidic ionic liquids [40], Fe 3 O 4 supported sulfonated-phenylacetic acid coated [41], etc. Unfortunately, some of these methods are not environmentally friendly and suffer from one or more limitations, such as the use of strongly acidic conditions, prolonged reaction times, high reaction temperature, low to moderate yields of the desired product, tedious work-up, toxicity, and poor recovery and reusability of the catalyst.…”

Silica–ZnCl2: An Efficient and Reusable Solid Catalyst for One Pot Synthesis of 5‐Methyl Mercaptothiocarbonyl‐4‐aryl‐3‐dihydropyrimidin‐2(1H)‐ones Under Solvent‐Free Conditions

“…Synthesis of polyfunctionalized dihydropyrimidine was first reported by Biginelli in 1893, involving a one‐pot condensation of an aldehyde, β‐ketoester, and urea under strongly acidic conditions . Since then, many improved protocols have been reported from time‐to‐time, some of them still suffer from drawbacks such as unsatisfactory yields, cumbersome product isolation procedures, and environmental pollution . We are reporting herein the application of silica–ZnCl 2 as an effective catalyst in multicomponent reactions under solvent‐free conditions for the synthesis of a small library of 5‐methylmercaptothiocarbonyl‐4‐aryl‐3‐dihydropyrimidin‐2( 1H )‐ones in good to excellent yields.…”