Three Distinct Reactions of 3,4-Dihydroisoquinolines with Azlactones:  Novel Synthesis of Imidazoloisoquinolin-3-ones, Benzo[a]quinolizin-4-ones, and Benzo[d]azocin-4-ones

Abstract

A facile and direct synthetic entry to tricyclic imidazoloisoquinolin-3-ones and benzo[a]quinolizin-4-ones is reported based on the ring annulation of 1-unsubstituted and 1-substituted dihydroisoquinolines with azlactones under neutral conditions in a one-step procedure. Bicyclic 2,3-dihydrobenzo[d]azocin-4-ones were also prepared using simple azlactone and 1-substituted dihydroisoquinolines in a one-pot reaction. [reaction: see text]

Synthesis of Benzoazocines from Substituted Tetrahydroisoquinolines and Activated Alkynes in a Tetrahydropyridine Ring Expansion

“…[1] Among them, eight-membered (azocine) and larger N-containing fusedring systems occupy a prominent place and deserve more investigation efforts from the point of view of organic chemistry. Alkaloids and drugs containing benzoazocine fragments in their structures exhibit extensive evidence of different activities: inhibition of α-glucosidase, [2] acetylcholinesterase, [3] antinociception activity, [4] antitumor activity, [5] antiinsectan activity, [6] and inhibition of HIV-1 replication. [7] Known synthetic routes towards the benzoazocine system include ring-closing metathesis, [8] intramolecular catalytic Friedel-Crafts reactions, [9] and palladium-catalyzed heteroannulation, [10] but only a few of these are really effective.…”

“…[7] Known synthetic routes towards the benzoazocine system include ring-closing metathesis, [8] intramolecular catalytic Friedel-Crafts reactions, [9] and palladium-catalyzed heteroannulation, [10] but only a few of these are really effective. [11] Recently, we have reported a novel method for the synthesis of tetrahydropyrrolo [2,3-d]azocines, [12] tetrahydroazocino [4,5-b]-and - [5,4-b]indoles, [13] and hexahydroazonino [5,6-b]indoles. [14] It is based on the enlargement of either the tetrahydropyridine or hexahydroazepine fragments in tetrahydropyrrolo [3,2-c]pyridines, tetrahydro-β-and -γ-carbolines, or tetrahydroazepino [3,4-b]-and - [4,3-b]indoles in the presence of activated alkynes.…”

A Practicable Synthesis of Oxazol-5(4H)-ones Through Hydrogenation: Scope and Applications

“…First, we conducted the preparation of Erlenmeyer oxazolones; these structures can be easily obtained by using literature protocols (Scheme ).…”

“…A simple method to overcome these adversities could be solved by using hydrogen. Thus, the well‐known Erlenmeyer azlactones or arylidene azlactone derivatives could be easily prepared from benzaldehyde derivatives and hippuric acid in the presence of sodium acetate and acetic anhydride and then submitted to hydrogenation reaction.…”

Synthetic Approaches toward the Benzo[a]quinolizidine System. A Review

“…The reactions of 166 with dihydroisoquinolines which cannot give tautomeric enamines lead to the formation of imidazoloisoquinolin-3-ones. 87 Acylamino compounds trans-and cis-167 containing o-bromophenyl substituent, were…”