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

NaIO4-catalyzed one-pot synthesis of dihydropyrimidinones at room temperature under solvent-free conditions

“…We then examined this reaction in different solvents and under different reaction temperatures, whereby the reaction gave better yields under neat conditions, and the products were obtained in good yields when the temperature was reduced to ambient with the prolonged reaction time (Tables 1 and 2). 108-110 -All the melting points (except the products of entry 4,6,7,9,11,13,15,17,20,26,27 and 32 are hitherto unknown) are in good agreement with those of literature report.…”

“…However, many of these one-pot procedures generally require strong protic or Lewis acids, prolonged reaction times, and high temperatures. Yadav [11a] reported that neutral LiClO 4 works well in the Biginelli reaction, but toxic solvent of acetonitrile is needed [11b, [12][13][14][15][16][17][18]. Thus, the use of a neutral alternative, and less hazardous solvents, or even those that do not need solvents at all, would extend the scope of useful one-pot Biginelli reaction for the synthesis of dihydropyrimidinones.…”

Synthesis, crystal structure and antibacterial studies of dihydropyrimidines and their regioselectively oxidized products

“…It is known that a lot of protocols were developed for performing Biginelli reaction, leading to the synthesis of H 2 Py with high yields under “green” conditions and simple work-up procedure. Using catalyst types such as I 2 /MWI, 67 Yb(PFO) 3 , 68 TMSCl/CAN, 69 [Hmim]HSO 4 –NaNO 3 , 70 CAN, 71 GaI 3 , 72 HBF 4 –SiO 2 , 73 Sm(ClO 4 ) 3 , 74 H 3 PMo 12 O 40 , 75 La(OTf) 3 , 76 Sc(OTf) 3 , 77 In(OTf) 3 , 78 RuCl 3 , 79 MgCl 2 ·6H 2 O, 80 CeCl 3 ·7H 2 O, 81 acetic acid, NH 4 Cl 17 and others, 3–14 it was not possible to perform a Biginelli reaction on the basis of all used aldehyde scaffolds, urea and methylacetoacetate. In addition to this, performing the synthesis in microwave reactor becomes more popular over the conventional method, due to the fact that microwave method increases speed, reproducibility and scalability of the reaction.…”

Synthesis of Dihydropyrimidines: Isosteres of Nifedipine and Evaluation of Their Calcium Channel Blocking Efficiency

“…Yadav and group attempted to synthesize DHPMs using the same strategy and were successful in producing nearly 13 DHPM derivatives with a yield varying from 82 to 90% [ 93 ]. Likewise, NiCl 2 .H 2 O, LaCl 3 .7H 2 O [ 94 ], MgBr 2 [ 95 ], iodine [ 96 ], and MgCl 2 .6H 2 O [ 97 , 98 ] are some other catalysts used for the DHPM synthesis.…”