Synthesis of heterocyclic compounds using amidines as their ene-1,1-diamine tautomers. II. Synthesis of 2,3-dihydropyridine, 3,4-dihydropyridine and 3,4-dihydropyrrol-2-one derivatives by the reaction of amidines with α, β-unsaturated carbonyl compounds

Abstract

N‐t‐Butylacetamidines 1 on heating with methyl vinyl ketone, acrolein or crotonaldehyde gave the 2,3‐dihydropyridine derivatives 4,5 or 6 via N‐alkylation of the acetamidines 1. Reaction of amidines 1 with phenyl 1‐propenyl ketone, benzalacetone or chalcone gave 3,4‐dihydropyridine derivatives 8, 9 or 10. These were obtained by C‐alkylation, achieved by Michael addition of the acetamidines 1 as their N,C‐tautomers ene‐1,1‐diamines 1′ to α,β‐unsaturated carbonyl compounds, and subsequent cyclodehydration of adducts. Reaction of 1 with ethyl 3‐benzoylacrylate gave 3,4‐dihydropyrrol‐2‐one derivatives 13.

Chemistry and Biology of Synthetic and Naturally Occurring Antiamoebic Agents

“…Amidines display a large variety of biological properties − and are utilized as precursors in many heterocyclic syntheses. − Metal complexes of amidines with a 1,2,4-triazole ring display low-temperature molecular ferromagnetics . Further bicyclic amidines have been identified as highly active acylation catalysts .…”

Synthesis of Heterocyclic Compounds Using Amidines as Their Ene-1,1-diamine Tautomers, IV: Synthesis of N-Bridged Heterocycles 1,2,3,4-Tetrahydropyrido[1,2-a]pyrimidin-6-ones and Methyl 1,2,3,4-Tetrahydropyrrolo[1,2-a]pyrimidin-7-ylideneacetates

“…In a previous article, we reported a facile synthesis for heterocycles by the reaction of amidines (via ene-1,1-diamines) with a,b-unsaturated carbonyl compounds. [6] In the course of our investigation of amidines (as ene-1,1-diamine N,C-tautomers), here we report the C-alkylation of 2-benzyl-1,4,5,6-tetrahydropyrimidines (1) with ethyl benzoylacetate (2) and dimethyl acetylenedicarboxylate (4), leading to 1,2,3,4-tetrahydropyrido[1,2-a] pyrimidin-6-ones (3) and methyl 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrimidin-7-ylideneacetates (5), respectively.…”

“…[9] 2-(4-Methoxybenzyl) -1,4,5,6-tetrahydropyrimidine (1e) This compound was obtained as white powder, 54% yield, mp 118-121 C; 1 H NMR: d 1.73 (2H, quin, J ¼ 5.7 Hz, CH 2 ), 3.29 (4H, br s, 2 Â NCH 2 ), 3.41 (2H, s, CH 2 ), 3.80 (3H, s, OCH 3 ), 6.86 and 7.19 (each 2H, d, J ¼ 8. 6 Hz, Ar-H), NH not observed; MS: (CI) m=z 205 (MH þ ).…”

Amidines: their synthesis, reactivity, and applications in heterocyclic synthesis

“…When a diglyme solution of the amidines 7O and ethyl-3-benzoylacrylate (122) was heated at 120 o C, 3,4-dihydropyrrol-2-one derivatives 123 were obtained (Scheme 58) 90. …”