Microwave‐assisted Synthesis of Dihydro Dibenzophenanthroline and Its Derivatives Using a Self‐catalyzed Friedlander Reaction

Abstract

One‐step microwave‐assisted synthesis of dihydro dibenzophenanthrolines are reported using a self‐catalyzed Friedlander reaction. The reaction is carried out in one step by simple microwave irradiation of 3,4‐dihydroacridin‐1(2H)‐one with 2‐amino‐benzophenone in the presence of acid catalysts with solvent‐free conditions. Thin‐layer chromatography was used to monitor the progress of the reaction; hence, it was observed that the reaction starts slowly and accelerates as it proceeds to ring fusion transformation. Synthesized compounds' isolated yield is enhanced in the absence of solvent systems with Friedlander catalyst under microwave irradiations.

Mn-Catalyzed Ligand-Free One-Pot Synthesis of (E)-6,7-Dihydrodibenzo[b,j][1,7]phenanthrolines and (E)-1,2,3,4-Tetrahydrobenzo[b][1,6]naphthyridines through Dehydrogenative Friedlander Annulation/C(sp3)–H Functionalization

“…The synthetic utility was further explored with a heterocyclic alcohol, 18. A mixture of 9 (1 mmol), 10 (1 mmol), and (1,3diphenyl-1H-pyrazol-4-yl)methanol (18) (1 mmol) in the presence of MnO 2 , KO t Bu, DES-1, and DES-2 was heated at 100 °C for 3 h to get the desired product (E)-2,10-dichloro-6-((1,3-diphenyl-1H-pyrazol-4-yl)methylene)-8,14-diphenyl-6,7dihydrodibenzo[b,j][1,7]phenanthroline (13l) (Scheme 3, equiv 3.1). The same reaction condition was followed for compound 15k.…”

“…Rajawinslin and co-workers have reported 3, involving iron/acetic acid medium via aldol addition, followed by intramolecular reductive cyclization (eq 1) . Kumaraswamy and co-workers have reported dihydrodibenzo phenanthrolines, 3, via Friedlander annulation through self-catalyzed reaction (eq 2) . Likewise, Kulikova, et al have synthesized 6, via cyclization of anthranilic acid (eq 3) .…”

“… 17 Kumaraswamy and co-workers have reported dihydrodibenzo phenanthrolines, 3, via Friedlander annulation through self-catalyzed reaction (eq 2). 18 Likewise, Kulikova, et al have synthesized 6, via cyclization of anthranilic acid (eq 3). 19 Alvarez-Pérezand co-workers have reported 8, under reflux conditions (eq 4).…”

Synthesis, Optical and Electrochemical Properties of Isomeric Dibenzophenanthroline Derivatives

“…The reaction, which proceeds via bromination of the active methylene group of 2 followed by in situ dehydrobromination of the bromo intermediate, has previously been used for aromatisation of other polycyclic aromatic compounds [13] . Compound 3 has been previously made in 86% yield by solvent‐free microwave‐assisted Friedländer condensation of an acridone with 1 and concentrated sulfuric acid [14a] . The acridone has been reportedly made by condensation of 1 with 1,3‐cyclohexadione in 99–100% yield, [14b— — d] producing an overall yield of 3 from 1 in 2 steps of 85–86% yield.…”