Synthesis of a new class of strongly fluorescent heterocyclic compounds: 3H-imidazo[4,5-a]acridine-11-carbonitriles

Design, Synthesis, Fluorescence Properties and Antibacterial Activities of New 8-Chloro-3-Alkyl-3H-Pyrazolo[4,3-a]acridine-11-Carbonitriles

“…As depicted in Scheme 1, the required starting materials 1-alkyl-5-nitro-1H-indazoles 1a-e were prepared by reaction of 5-nitro-1H-indazole with different alkyl halides in DMF and KOH using a literature method. 22 The treatment of 1-alkyl-5-nitro-1H-indazoles 1a-e with 2-(4-chlorophenyl) acetonitrile 2 led to the formation of the new 8-chloro-3-alkyl-3H-pyrazolo[4,3-a]acridine-11-carbonitriles 3a-e by way of the nucleophilic substitution of hydrogen 24 followed by the ring closure which proceeds via an electrocyclic pathway [10][11][12][13][14][15] in basic MeOH solution in good yields. The simple work-up procedure was performed by filtration of the precipitated product and washing with water and EtOH, respectively.…”

“…Based on these aspects and in continuation with our research work on the synthesis of new fluorescent nitrogen heterocycles [10][11][12][13][14][15] and bioactive [16][17][18][19][20][21] nitrogen heterocyclic compounds, we now decided to examine the transformation of alkylated 5-nitro-1H-indazoles and 2-(4-chlorophenyl) acetonitrile to new 8-chloro-3-alkyl-3H-pyrazolo [4,3-a]acridine-11-carbonitriles in basic media and to evaluate their spectroscopic properties and biological activities.…”

Synthesis, spectroscopic characterization and DFT calculations of a new highly fluorescent heterocyclic system: imidazo[4,5-a]quinindoline

“…In the following mechanism [17][18][19][20][21][22][23] the ring closure proceeds via an electrocyclic pathway, wherein intermediate B is converted into C followed by loss of one H 2 O molecule, whereupon compounds 3a-d are obtained (Scheme 2).…”

“…[17][18][19][20][21][22] In Scheme 3 neutral and some charge-separated mesomeric structures of 3a-d are presented. As seen in this scheme, there are two nitrogen donors which can explain the shoulder on the right side of the peaks in emission spectra of compounds 3a-d (Figure 3).…”

“…Based on these aspects and in continuation with our research work on the efficient synthesis of new dyes and fluorescent nitrogen heterocyclic compounds, [17][18][19][20][21][22][23] we examined the transformation of 1-alkyl-5-nitro-1H-benzoimidazole with 2-(1-alkyl-1H-3-indolyl)acetonitrile to new fluorescent heterocyclic system imidazo [4,5-a]quinindoline via the nucleophilic substitution of hydrogen. 24,25 The fluorescence properties of these new heterocyclic compounds and DFT calculations of one structure by using the B3LYP hybrid functional and the 6-311+G(d,p) basis set have also been studied.…”