Starting reagents were purchased from commercial sources and were used without any additional purification (Acros Organics, Geel, Belgium). 1H and 13C-NMR spectra were acquired on a Jeol JNM-ECA 600 spectrometer (Jeol Ltd, Tokyo, Japan) (with operating frequencies of 600 and 150 MHz, respectively) at room temperature and referenced to the residual signals of the solvent. The solvent used for NMR was CDCl3. Chemical shifts are reported in parts per million (δ/ppm). Coupling constants are reported in Hertz (J/Hz). The peak patterns are indicated as follows: s, singlet; d, doublet; t, triplet; q, quadruplet; m, multiplet; dd, doublet of doublets and br s, broad singlet. Infrared spectra were measured on an Infralum FT-801 FT/IR instrument (Simex, Novosibirsk, Russia). The wavelengths are reported in reciprocal centimeters (νmax/cm−1). UV spectra were recorded using Varian Cary 50 (Agilent, Santa Clara, CA, USA). Mass spectra were recorded with LCMS-8040 Triple quadrupole liquid chromatograph mass-spectrometer from Shimadzu (ESI) and Kratos MS-30 mass-spectrometer (EI, 70 eV) (Shimadzu, Tokyo, Japan). HRMS spectra were recorded on a Bruker MicrOTOF-Q II (Bruker, Billerica, MA, USA). The reaction progress was monitored by TLC and the spots were visualized under UV light (254 or 365 nm) (UVGL-25, UVP, Upland, CA, USA). Column chromatography was performed using silica gel (60–75 mesh) (Merck KGaA, Darmstadt, Germany). Melting points were determined on a SMP-10 apparatus (Stuart, Stone, UK) and were uncorrected. Solvents were distilled and dried according to standard procedures.
3.2. Methyl (2E)-3-[3-Benzyl-2-(3-methoxy-3-oxoprop-1-yn-1-yl)-2-(1-naphthyl)imidazolidin-1-yl]acrylate
Methyl propiolate (0.182 mL, 2.2 mmol) was added to a solution of 1-benzyl-2-(1-naphthyl)-4,5-dihydro-1H-imidazole (0.3 g, 1 mmol) in dry ether (4 mL) and the resulting solution was stirred for 3h at rt. After the interaction completion (TLC monitoring) the solution was concentrated approximately two times in vacuo and cooled to 0–5 °C. The resultant crystals were filtered and dried at rt to give the title compound 3 (404 mg, 85%) as a yellow powder; m.p. 142–143 °C (Et2O). Purification by column chromatography on SiO2 (CHCl3/Hexane, 100:50) instead of crystallization gave 440 mg (92%) of the title compound 3. TLC: Rf =0.35 (CHCl3). 1H-NMR (600 MHz, CDCl3) δ, ppm: 2.95 (q, 1H, J = 9.1 Hz), 3.32 (d, 1H, J = 13.1 Hz), 3.38 (t, 1H, J = 8.3 Hz), 3.50 (t, 1H, J = 9.1 Hz), 3.51 (s, 3H), 3.56 (d, 1H, J = 12.6 Hz), 3.69 (q, 1H, J = 17.7 Hz), 3.89 (s, 3H), 4.68 (d, 1H, J = 13.1 Hz), 6.98 (dd, 2H, J = 6.3, J = 2.8 Hz), 7.11 (d, 1H, J = 13.1 Hz), 7.14–7.16 (m, 3H), 7.48–7.52 (m, 3H), 7.88–7.89 (m, 1H), 7.95 (d, 1H, J = 8.1 Hz), 8.28 (d, 1H, J = 7.6 Hz), 8.45 (d, 1H, J = 8.6 Hz). 13C-NMR (150 MHz, CDCl3) δ, ppm: 168.9 (Cq), 153.8 (Cq), 144.1 (CH), 137.3 (CH), 135.2 (CH), 132.4 (CH), 131.3 (CH), 130.1 (CH), 129.4 (Cq), 129.2 (Cq), 128.8 (2C, CH), 128.4 (2C, CH), 127.4 (CH), 126.2 (CH), 126.2 (Cq), 125.9 (CH), 124.5 (Cq), 89.8 (CH), 85.0 (Cq), 81.9 (Cq), 81.3 (Cq), 53.7 (CH2), 53.2 (CH2), 50.7 (CH3), 48.0 (CH3), 44.9 (CH2). EI-MS (m/z, M+): 455 (100%), 456 (30%), 457 (6%). HRMS Electrospray ionization (ESI) m/z calcd for C28H27N2O4+ = 455.1965, found 455.1965. λmax, MeCN: 220 (ε = 48,800), 275 (ε = 29,800) nm. IR (KBr), ν (cm−1): 3028 (Ar-H), 2948 (C-H), 2835 (C-H), 2220 (C≡C), 1715 (C=O), 1614 (C=C), 1245 (C-O ether), 1158 (C-O ether).