Abstract
AbstractFree catalyst one-pot three components coupling of aldehydes, β-dicarbonyl compounds, and urea was performed to afford both the corresponding 3,4-dihydropyrimidine-2-ones (DHPOs, (1–9)a) and their sulfur analogs 3,4-dihydropyrimidine-2-thiones (DHPTs, (1–9)b), synthesized in the presence of uranyl acetate (UA) and succinimide sulfonic acid (SuSA) as catalysts under the same conditions via Biginelli condensation protocol. Interestingly, the free catalyst reactions were performed for 4 h for DHPOs with the yields of high to excellent, while in the cases of DHPTs, the yield was lower. But when the UA or SuSA was used, the yields (both of DHPOs and DHPTs) were high to excellent and the reaction times were either 2.5 or 1 h, respectively. Also, these two catalysts were recyclable for four consecutive runs.
Highlights
The Italian chemist Biginelli (1891a, 1891b), observed the reaction between an ammonia source and an aldehyde in equimolar ratio and urea in acidic alcoholic solution to obtain new compounds, well known as 3,4-dihydropyrimidine-2(1H)-ones (Kenner & Todd, 1957; Zaugg & Martin, 1965)
In continuation of our investigations on the synthesis of (DHPOs and DHPTs) via Biginelli protocols (Shockravi, Kamali, Sharifi, Nategholeslam, & PahlavanMoghanlo, 2013), here in, we report efficient new catalysts (UA and succinimide sulfonic acid (SuSA)) and compare with catalyst free method in the preparation of such products
In continuation of our investigations on the synthesis of (DHPOs and DHPTs) via Biginelli protocols, here in, we report efficient new catalysts (UA and SuSA) and compare with catalyst free method in the preparation of such products
Summary
The Italian chemist Biginelli (1891a, 1891b), observed the reaction between an ammonia source and an aldehyde in equimolar ratio and urea in acidic alcoholic solution to obtain new compounds, well known as 3,4-dihydropyrimidine-2(1H)-ones (Kenner & Todd, 1957; Zaugg & Martin, 1965) After years from this discovery, emphasis was on understanding the course of reaction and some emphasis on structural variants as well. In continuation of our investigations on the synthesis of (DHPOs and DHPTs) via Biginelli protocols (Shockravi, Kamali, Sharifi, Nategholeslam, & PahlavanMoghanlo, 2013), here in, we report efficient new catalysts (UA and SuSA) and compare with catalyst free method in the preparation of such products
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