Optically active imidazole N-oxides derived from l-prolinamine1

Abstract

Starting with (S)-1-benzylprolinamine and alpha-hydroxyimino ketones, enantiomerically pure bisheterocyclic imidazole N-oxides bearing the (S)-configured N-benzyl(pyrrolidin-2-yl)methyl residue were prepared. These N-oxides reacted with 2,2,4,4-tetramethylcyclobutane-1,3-dithione to give the corresponding optically active imidazole-2-thione derivatives via a sulfur transfer reaction. Reduction of the N-oxides with Raney-nickel led to deoxygenation, whereas catalytic hydrogenation (Pd/C) in ethanol occurred with simultaneous deoxygenation and debenzylation, leading to optically active 1-(pyrrolidin-2-yl)methyl-1H-imidazoles. Alkylation of the prepared imidazole N-oxides and their respective imidazoles with butyl and hexyl bromide and subsequent anion exchange gave optically active N-alkoxy-and N-alkylimidazolium tetrafluoroborates, respectively, with the properties of 'room temperature ionic liquids'.

l-Proline as a Valuable Scaffold for the Synthesis of Novel Enantiopure Neonicotinoids Analogs

“…Yield: 68%, colorless oil, spectral data matched with previous reports; the 1 H NMR data is provided here for convenience. 1 H NMR (500 MHz, CDCl 3 ) δ: 7.34–7.28 (m, 4H), 7.25–7.21 (m, 1H), 3.97 (d, J = 13.1 Hz, 1H), 3.30 (d, J = 13.1 Hz, 1H), 2.98–2.91 (m, 1H), 2.77 (dd, J = 12.9, 5.4 Hz, 1H), 2.71 (dd, J = 12.9, 3.4 Hz, 1H), 2.59–2.52 (m, 1H), 2.24–2.16 (m, 1H), 1.94–1.81 (m, 2H), 1.74–1.63 (m, 2H), 1.60–1.51 (m, 2H).…”

“…The insecticidal activities of title compounds against Xyleborus aff inis were tested according to the previously reported procedure of the contact toxicity on filter paper. 20 A Whatman grade 42, ashless filter paper (5 cm diameter) was placed in a glass Petri dish (50 × 17 mm diameter). An aliquot of 0.25 mL of the solution of a 0.05 M compound in dimethyl sulfoxide/water (1:1) was applied uniformly to the filter paper disc; the mixture of solvents was used as the negative control, and the solution of dinotefuran at the same concentration was used as positive control.…”

“…The insecticidal activities of title compounds against Xyleborus affinis were tested according to the previously reported procedure of the contact toxicity on filter paper . A Whatman grade 42, ashless filter paper (5 cm diameter) was placed in a glass Petri dish (50 × 17 mm diameter).…”

Synthesis, insecticidal activity, and ensembled docking of nitroguanidines bearing S‐ and R‐proline

“…The crude product was used without further purification.2.2.8 Data for N-benzyl-L-prolinol S4Yield: 83%, slightly yellow oil. Spectral data matched with previous reports;16 the 1 H NMR data are provided here for convenience. [⊍] 20 = −56 (c = 1, CH 3 OH).…”

Synthesis of optically active polyheterocycles containing pyrrolidine, imidazole, and 1,2,3-triazole rings

“…2 The initially obtained In search for optically active polyheterocycles derived from (S)-proline, a series of 2-unsubstituted imidazole N-oxides of type 1 was used as substrates for the conversion into optically active polyheterocycles containing a 1,2,3-triazole residue along with imidazole and proline units.…”