Synthesis of some new indolizines

Abstract

The reaction between 4‐dimethylaminopyridine (DMAP) and 2‐bromoacetophenone(s) readily gives 1‐ [2‐(4‐substitutedphenyl)‐2‐oxoethyl]‐4‐(dimethylamino)pyridinium bromide (1–14). Action of aqueous NaOH on 1–8 generates the corresponding pyridinium ylide (15–22), which is isolated as a colored stable crystalline solid. Addition of 15–22 to dimethylacetylene dicarboxylate (DMAD) gives dimethyl 3‐(substitutedbenzoyl)‐7‐(dimethylamino)indolizine‐1,2‐dicarboxylate (23–30) in 46–62% yield.

A Facile Synthesis of Pechmann Dyes

“…The pyridinium bromide is easily available from w-bromoacetophenone and 4-dimethylaminopyridine (4-DMAP). [9] In sharp contrast to previous experiments, the reaction mixture developed a deep red color within several minutes, followed by the separation of a yellow fluorescent solid. During the work-up, dimethyl fumarate was always isolated, along with a crude mixture of other reaction products; its isolation proved to be very important for the mechanistic rationalization of the process (see below).…”

[1-Methoxy-3-(pyridin-2-yl)indolizin-2-yl](pyridin-2-yl)methanone

“…Indolizines are used as dyes (Weidner et al, 1989), pharmaceuticals (Singh & Mmatli, 2011), and spectroscopic sensitizers (Gilchrist, 2001;Katrizky et al, 1999;Sarkunam & Nallu, 2005;Vemula et al, 2011;Weeler, 1985a,b). Indolizines are rather scarce in nature whereas the reduced form of these heteroaromatic bicyclic compounds, the indolizidines, are quite common, see: Michael (2007) and references therein.…”

One-pot Synthesis of 3-Aryl-substituted 1-Hydroxy-2-acylindolizines

“…Monomorine I [9], pumiliotoxines [10], and tashiromine [11] represent characteristic examples of this substance class. For these applications of indolizines a well-defined substitution pattern is required and has been the target of diverse research efforts for the construction of substituted indolizines [5,12,13]. Therefore, different transition metal-mediated and metal-free strategies for the synthesis of substituted indolizines were investigated over the last years [13 -23].…”