Hassan A. K. Abd El-Aal

Friedel–Crafts Chemistry. Part 39. Unprecedented Facile Route to the Synthesis of Benzo[b][1]benzazepines via Intramolecular Friedel–Crafts Cyclialkylations

A series of six pharmaceutically promising 5,6-dihydro-11H-benzo[b][1]benzazepine derivatives (1c–h) were cleanly prepared by Friedel–Crafts cyclialkylations of nitrogen-containing alkanols in the presence of AlCl3, 85 % H2SO4 or polyphosphoric acid catalysts. The precursor alkanols (13a–f) were readily prepared by reaction of two synthesized carboxylic acid esters (12a, b) with different Grignard reagents. Also, two dibenzo[b,f]azepinones (15a, b) were prepared by Friedel–Crafts cycliacylation and reduced to the corresponding 5,6-dihydro-11H-benzo[b][1]benzazepines (1a, b). Overall, this approach allows easy and efficient access to polytricyclic amines from easily synthesized alkanols or cycloketones. A plausible carbocation mechanism is proposed to account for the results.

Friedel–Crafts Chemistry. Part 46. Unprecedented Construction of Tricyclic Pyrazolo[3,4-b]quinolines, -[1,8]naphthyridines, -azepines, -azocines, -pyrido[3,2-g]azocines, and pyrazolo[3,4-b]azonines via Friedel–Crafts Ring Closures

A series of keto-substituted pyrazolo[3,4-b]quinolines, pyrazolo[3,4-b][1,8]naphthyridines, benzo[e]pyrazolo[3,4-b]azepines, benzo[g]pyrazolo[3,4-b]azocines, pyrazolo[3,4-b]pyrido[3,2-g]azocines, and benzo[g]pyrazolo[3,4-b]azonines scaffolds were synthesized via a Friedel–Crafts cyclialkylation approach. The precursor acids were obtained by utilizing the modified Ullman coupling reactions of 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carboxylic acid with different aryl amines followed by ring closures in the presence of AlCl3/CH3NO2 or P2O5 or polyphosphoric acid catalysts. Particular attention is given to the novel structures especially in regard to the promising pharmaceutical and therapeutic values associated with their skeletons.

Friedel–Crafts Chemistry. Part 48. Concise Synthesis of Condensed Azaheterocyclic [1,8]naphthyridinones, Azepino-, Azocino-, and Azoninoquinoline Systems via Friedel–Crafts Ring Closures

Unprecedented construction of a novel series of quinoline heteropolycycles (tetracyclic keto-analogues of [1,8]naphthyridinones, azepino-, azocino- and azonino[2,3-b]quinolinones systems) 10a–i by Friedel–Crafts cycliacylation reactions is described. Starting heterocyclic acids precursors 3a–i were prepared from easily accessible 2-chloroquinoline-3-carbaldehyde 1 via a three different synthetic pathways. Acid-catalyzed ring closures of the resulting tosylated acids were achieved under the influence of both Bronsted and Lewis acid catalysts. The present strategy enables a straightforward synthesis to fused tetracyclic quinolinone skeletons as demonstrated by concise and atom-economical syntheses.

Friedel–Crafts Chemistry. Part 43. A Convergent Construction of Some New Bridged Aza-Bicyclic Analogues of Azocine, Azonine, and Azecine via Friedel–Crafts Ring Closures

Our present study provides an expedient general approach for the synthesis of some novel bridged dibenzo-azocinone, -azoninone, -azecinone, -azocine, -azonine, and -azecine derivatives via Friedel–Crafts intramolecular ring-closure reactions. The methodology is realized by a four-step protocol involving first preparation of 7-methyl-3,3-diphenylindoline through the reduction of 7-methyl-3,3-diphenylindolin-2-one followed by N-alkylations with different haloesters (α-, β- or γ-). The resulting indoline ester derivatives were allowed to react both by addition of Grignard reagents to afford alcohols and by hydrolysis to afford acids. Particular attention has been given to the novel structures especially in regard to the promising pharmaceutical and therapeutic values associated with their skeletons.

Modern Friedel-Crafts Chemistry. Part 38. Facile Synthesis of Acenaphthenes via Direct and Rearranged Intramolecular Friedel-Crafts Cyclialkylations of Intermediate Carbinols

A novel one-pot synthesis of six di-, tri-, and tetra-substituted acenaphthenes 18a-f via direct and/or rearranged Friedel-Crafts cyclialkylations of seven novel carbinols 1a-g is described. The methodology involves treatment of alkanols 1a-g in the presence of both Brønsted (PPA, H2SO4) and Lewis (AlCl3/CH3NO2) acid catalysts. The method offers several advantages such as high yields, high selectivities, and easily accessible starting materials. A plausible mechanism for this type of Friedel-Crafts cyclialkylation is proposed.

Modern Friedel-crafts chemistry. part 31. An efficient synthetic approach to mono-, di- and triphenylindans via direct Friedel-crafts cyclialkylaion of selected phenylated alkanols

Facile procedures for the synthesis of mono-, diand triphenylindanee derivatives from the alcohols 1-4 are described thus treatment with 85% H2SO4, AlCl3/CH3NO2, H3PO4 and/or PPA under varying conditions produced 1,1-dimethyl-3-phenylindanee 6 from 2-methyl-4,4-diphenyl2-butanol 1, 3,3-dimethyl-1,1-diphenylindanee 9 from 2-methyl-4,4,4-triphenyl-2-butanol 2, 1methyl-1,3-diphenylindanee 12 from 2,4,4-triphenyl-2-butanol 3 and 1,1,3-triphenylindanee 15 from 1,1,3,3-tetraphenyl-1-propanol 4. The starting and final products were characterized by elemental, IR, H NMR and MS analyses.