�ber Heterocyclen, 12. Mitt.: Zur Bromierung der 2-Oxo-6-methyltetrahydropynimidine

On the reaction of 3,4‐dihydropyrimidones with nitric acid. Preparation and x‐ray structure analysis of a stable nitrolic acid

“…In general, this methyl group in Biginelli DHPMs is readily attacked by electrophiles [12]. With elemental bromine in chloroform, for example, selective mono-and dibromination of the methyl group in 1 can be achieved at 0 °C [29]. It is therefore reasonable to assume that under the reaction conditions used here, involving the electrophilic nitronium species, a similar pathway is followed.…”

Creating chemical diversity space by scaffold decoration of dihydropyrimidines

“…Functionalization of this methyl group is easily achieved by stepwise bromination. Stepwise substitution of the methyl group upon bromination yields 6-bromomethyl 17 and 6-dibromomethyl derivatives 18, respectively [15]. The bromomethyl compounds 17 are susceptible to a number of nucleophilic substitution reactions.…”

Ferric chloride/tetraethyl orthosilicate as an efficient system for synthesis of dihydropyrimidinones by Biginelli reaction

“…This simple procedure has been effective in a number of the Biginelli reactions with simple unsubstituted, or para-and meta-substituted aldehydes and acetoacetate esters. [3][4][5][6][7][8][9] However, in cases of significant steric hindrance in both counterparts the reaction yields drop drastically. In order to improve the yield of dihydropyrimidinones, a few other multistep approaches using aldehyde 10 [30][31][32] The most efficient catalysts are bismuth triflate 33,34 and trimethylsilyl triflate, 35 which allow the preparation of dihydropyrimidinones in good to high yields at room temperature.…”