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

Abstract

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 40. An expedient novel synthesis of some dibenz-azepines, -azocines, 11H-benzo[f]pyrido[2,3-b]azepines and 6H-benzo[g]pyrido[2,3-c]azocines

“…, 221 (18), 206 (35), 191 (21), 178 (41), 166 (24), 151 (17), 109 (33), 104 (15), 90 (12), 76 (8). Anal.…”

“…[36][37][38][39][40][41] In our previous work 41 we developed a synthetic methodology for the construction of nine substituted 5,6- H NMR data allowed an unambiguous statement of the formation of the heterocyclic alkanols. Thus, the 1 H NMR spectrum for alcohol 9a displayed five signals in which aromatic protons appeared at δ 6.45-7.7.…”

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

“…That inspired us to start a systematic study based on our long experience in Friedel-Crafts reactions to develop ringclosure strategies for the construction of bridged and nonbridged medium-sized heteropolycycles. In our previous work, [40][41][42][43] we introduced novel methods for the construction of nine substituted 10,11-dihydro-5H-dibenz [b,f]azepines (iminodibenzyls), 5,6,11,12-tetrahydro-5H-dibenz[b,f]azocines, 5,6-dihydro-11H-benzo [f]pyrido [2,3-b]azepines, and 5,6,11,12tetrahydro-6H-benzo [g]pyrido [2,3-c]azocines via Friedel-Crafts ring closures of nitrogen-containing alcohols and carboxylic acids.…”

Friedel-Crafts chemistry: Part 41. A new facile synthesis of indeno[1,2-c] pyrazoles, 2H-benzo[g]indazoles and benzo[6,7]cyclohepta[1,2-c]pyrazoles via Friedel-Crafts ring closures

“…The procedures [46][47][48][49][50][51][52][53][54] described earlier for cyclialkylation of acids and alcohols with AlCl3/CH3NO2 or P2O5 or PPA catalysts were essentially followed. In all reactions, the crude oily or solid products were purified by flash column chromatography (basic alumina, EtOAc:n-hexane, 3:1, v:v) gave the pure products 1a,b, 2a-d and 3a-d.…”

“…In recent communications [46][47][48][49][50], we have demonstrated simple alternative procedures in the construction of novel and known heterocyclic systems proving the synthetic utility of Friedel-Crafts [51][52][53][54] cyclialkylation approach. The results manifested that a number of difficult heterocyclic skeletons can be easily prepared with the advantages of short reaction time and high yield.…”