Synthesis and properties of 1‐aryl‐2‐alkyl‐1,4,5,6‐tetrahydropyrimidines

Abstract

A general method is described for the synthesis of 1‐aryl‐2‐alkyl‐1,4,5,6‐tetrahydropyrimidines 1, by cyclization of N‐acyl‐N′‐aryltrimethylenediamines 2 with trimethylsilyl polyphosphate. Precursors 2 were obtained by aminolysis of the corresponding N‐(3‐bromopropyl)amides 3. The 1H nmr spectra of tetrahydropyrimidines 1 are analyzed, discussing the influence of substituents in positions 1 and 2 of the heterocyclic ring. Alkaline hydrolysis of compounds 1, which originates exclusively N‐acyl‐N′‐aryltrimethylenediamines 2, through an intermediate carbinolamine, was also studied. Cleavage of such an intermediate is discussed in the light of the stereoelectronic control theory. Reduction of compounds 1 with borane, leads regiospecifically to N‐alkyl‐N′‐aryltrimethylenediamines 6.

Conformational Studies by Dynamic NMR. 84.1Structure, Conformation, and Stereodynamics of the Atropisomers ofN-Aryl-tetrahydropyrimidines

“…Material . 1-Aryl-2-substituted-1,4,5,6-tetrahydropyrimidines 1 − 4 were synthesized by ring closure of the corresponding N -acyl- N ‘ -aryltrimethylenediamines. − Yields and physical data of new compounds are reported as Supporting Information.…”

1,n-Diamines. Part 3: Microwave-assisted synthesis of N-acyl-N′-arylhexahydropyrimidines and hexahydro-1,3-diazepines

“…10 The synthetic precursors of N-acyl-N 0 -arylimidazolidines or hexahydropyrimidines, namely N-acyl-N 0 -aryldi (or tri)methylenediamines, are prepared by acylation of the corresponding N-(xbromoalkyl) amine followed by aminolysis. 11 This strategy is not suitable for tetramethylenediamine derivatives, which can alterna-tively be synthesized by N-monoacylation of N-arylputrescines. 12 Selectively N-substituted 1,4-diaminobutanes are of biochemical and pharmacological interest as synthetic analogs of the natural polyamine putrescine.…”

Synthesis, NMR characterization andab initio6-31G* study of 1-aryl-2,3-dialkyl-1,4,5,6-tetrahydropyrimidinium salts

“…Reagents, solvents and starting materials were purchased from standard sources and purified according to literature procedures. 1-Aryl-2-alkyl-1,4,5,6-tetrahydropyrimidines 2a-i were described in the literature [21].…”