No abstract

No abstract

Novel 9-aminoimidazo[1,2-a:5,4-b']dipyridine-6,8-dicarbonitriles were prepared via the Michael addition reaction of readily accessible 2-(3H-imidazo[4,5-b]pyrid-2-yl)acetonitrile with arylidenemalononitriles. The regioselectivity of the reaction was supported by theoretical calculations at the DFT level. In contrast, the reaction of the appropriate bis-arylidenemalononitrile with 2-(3H-imidazo[4,5-b]pyrid-2-yl)acetonitrile under similar reaction conditions gave the corresponding bis[2-(3H-imidazo[4,5-b]pyrid-2-yl)acrylonitriles].

Table of Contents 1. Experimental S2 2. 1 H and 13 C NMR spectra for compounds 1a-h; 9; 18 and 19a-d S6 S2 Experimental Materials and methods Melting points were determined in open glass capillaries with a Gallenkamp apparatus. The infrared spectra were recorded in potassium bromide disks on a Pye Unicam SP 3-300 and Shimaduz FTIR 8101 PC infrared spectrophotometer. NMR spectra were recorded using a Varian Mercury VXR-300 NMR spectrometer or Bruker Ultrashield 400 MHz or Ascend 400 MHz (1H: 300 or 400 MHz, 13C: 75 or 100.6 MHz) instruments using DMSO-d6 as solvent. Mass spectra (EI) were obtained at 70 eV using a type Shimadzu GCMQP 1000 EX Spectrometer. Elemental analyses were performed on a Perkin-Elmer 240 micoanalyser at the Micro analytical Center of Cairo University. Compounds 10ai [42] and 13a-i [22] were prepared according to literature. General procedure for the synthesis of compounds 1a-h.Method A. To a mixture of bisaldehydes 10a-h (1 mmole), malononitrile ( 5) (2 mmole) and 2-(1Hbenzo[d]imidazol-2-yl)acetonitrile (11) (2 mmole) in absolute ethanol (25 mL), piperidine (2 mmole) was added. The reaction mixture was heated at reflux for 2 h. The crude solid was isolated and recrystallized from the proper solvent. Method B. To a mixture of appropriate bis(arylidene malononitrile) 13a, 13b or 13f (1 mmole) and 2-(1H-benzo[d]imidazol-2-yl)acetonitrile (11) (2 mmole) in absolute ethanol (15 mL) piperidine (2 mmole) was added. The reaction mixture was heated at reflux for 2 h. The crude solid was isolated and recrystallized from the proper solvent to give 1a, 1b and 1f, respectively. Method C. To a mixture of 3,3'-((alkane-1,3-diylbis(oxy))bis(2,1-phenylene))bis-(2-(1Hbenzo[d]imidazol-2-yl)acrylonitrile) (18) (1 mmole) and malononitrile (5) (2 mmole) in absolute ethanol (15 mL) piperidine (2 mmole) was added. The reaction mixture was heated at reflux for 2 h. The crude solid was isolated and recrystallized from DMF to give 1a. 3,3'-((Propane-1,3-diylbis(oxy))bis(2,1-phenylene))bis(1-aminobenzo-[4,5]imidazo[1,2a]pyridine-2,4-dicarbonitrile) (1a).

No abstract