3-[Benzyl-(1,5-dimethyl-1H-pyrazol-3-ylmethyl)-amino]-propionitrile

The products of aza-type Michael addition, i.e., β-amino carbonyl compounds and their derivatives, are often used as peptide analogs or precursors of optically active amino acids, amino alcohols, diamines, and lactams [1]. Moreover, β-amino carbonyl functionalities are ubiquitous motifs in natural products such as alkaloids and polyketides [2]. Herein, we report the synthesis of new product using aza-type Michael reactions under mild conditions.

To a mixture of 3-chloromethyl-1,5-dimethylpyrazole 1 [3] (0.51g, 3.53mmol) and sodium carbonate (1.5g, 14.12mmol) in 32 mL of acetonitrile was added slowly 3-(benzylamino)propionitrile 2 [4] (0.56g, 3.53mmol). The mixture was stirred at room temperature for four days. The solid material (Na₂CO₃, NaCl) was filtered and the filtrate was concentrated under reduced pressure to give the title compound 3 as yellow oil (85%).

¹H-NMR (300 MHz, CDCl₃): δ= 7.24-7.40(CHarom, 5H, m) ; 6.02(CHpyr, 1H, s) ; 3.68(N-CH₃, 3H, s); 3.66(N-CH₂-C, 2H, s); 3.62 (C₆H₅-CH₂, 2H, s); 2.76-2.81(CH₂-CH₂-CN, 2H, t, J = 7.66 Hz); 2.42-2.47 ( N-CH₂, t, J = 7.66 Hz); 2.24 ( CH₃, 3H, s).

¹³C-NMR (CDCl₃, 75 MHz): δ= 147.91(j); 139.85(l); 138.93(e); 129.29 and 129.19 (f); 128.79(g); 127.65(h); 119.37(a); 105.64(k); 58.67(d); 51.22(i); 48.82(c); 36.28(n); 16.63(b); 11.64(m).

EI-MS (70 eV, m/z): 228; 173 (2.4); 119; 95(4.7); 91 (37.3).