New uses of Westphal condensation: Synthesis of flavocorylene and related indolo[2,3-a]quinolizinium salts.

New route to pyrido[1,2-b]pyridazinium inner salts. Evidence of a 1,3-dipolar cycloaddition-ring expansion process

“…2-Alkyl and 2-amino substituted structures 2 have the potential to function as 1,4-dinucleophiles via deprotonation and are capable of reacting with 1,2-diearbonyl compounds (Westphal reaction) [3] to give a variety of azonia derivatives possessing a quaternary bridgehead nitrogen [4][5][6][7][8][9][10][11]. By contrast, with the exception of a few examples [12][13][14][15] relatively less attention has been paid to the possibility of using ylides 3 as 1,4-nucleophile-electrophiles (Fig.…”

Synthesis and Cytotoxic Activity of pyridazino[1′,6′:1,2]pyrido[3,4-b]indol-5-inium derivatives as anti-cancer agents

“…The method was applied to the synthesis of the naturally occurring alkaloid flavocorylene and related zwitterionic indolo[2,3-a]quinolizinium compounds. 15 Continuing our work in the field, we describe in this communication the synthesis of several new (2) or harmine (3), a series of compounds 4 (harmane series), 5 (harmol series) and 6 (harmine series) were prepared, with variations at the domains 1 (bromo, nitro, amino, alkoxy or hydroxy), 2 (carbamate, ester, amide, aliphatic saturated or unsaturated) and 3 (aliphatic saturated, unsaturated or aromatic) (Fig. 2).…”

“…On the other hand, 3 was aminated by MSH to yield 18. 15 Then, Westphal reaction was performed on 17 and 18 to give 6c-g and 6a,b respectively. Finally, compounds 6a and 6b were treated with base to give 19 which was then alkylated to yield 6h-k.…”

The first example of an intramolecular Westphal reaction. Synthesis of a new aza-quinolizinium type system

“…Although the procedure has been described for C-C [5][6][7], N-N [8-1 l] and N-C [12][13][14][15] substrates, it had always being used in its intermolecular version.…”