Contributions to syntheses of pyrrolo[2,1-a]phthalazines

Generation of pyrrolo[2,1‐a]isoquinoline derivatives from N‐ylides: Synthetic control and structural characterization

“…On the basis of the results highlighted in this paper and the reported literature [9,12,13], we can conclude that the primary cycloadducts of type 3 (Scheme 1) rearrange to the trans isomer of type 4 or 5.…”

“…However, with the unexpected trans configuration observed for the dihydro pyrrolo[2,1-a]phthalazines [12] in mind, we reinvestigated the structure of the dihydro derivative 10 by single crystal X-ray analysis. Figure 2 shows the molecular structure of 10 and the crystallographic numbering scheme.…”

“…By comparison, if no oxidizing agents were used, it was observed that in different solvents (CH 2 Cl 2 , benzene, DMF, MeCN) the reaction between the corresponding N-ylides and symmetrical acetylenic dipolarophiles leads to the formation of dihydro derivatives together with the aromatic compounds. These dihydro derivatives can be assigned as pyrrolo[2,1-a]phtalazines (type 4) [12] and pyrrolo[1,2-a][1,10]phenanthrolines (type 5) [13] (Scheme 1), which are important synthetic intermediates.…”

1,3-Dipolar cycloaddition between acetylenic dipolarophiles and sydnone-N-ylides as bis(1,3-dipoles)

“…33 The most versatile method of synthesis of pyrroloazines is the 1,3-dipolar cycloaddition reaction between heteroaromatic N-ylides and acetylenic dipolarophiles. [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] Herein we report the generation of sydnone-N-ylides as bis (1,3-dipoles) and their reactivity in the 1,3-dipolar cycloaddition reaction with acetylenic dipolarophiles. 1,3-Dipolar cycloaddition reaction of sydnone-N-ylides, as model bis (1,3-dipoles), with acetylenic dipolarophiles in 1,2-epoxybutane under reflux gave exclusively pyrroloazines containing a sydnone moiety that resulted by preferred reaction of the N-ylide 1,3-dipole with the acetylenic dipolarophiles.…”

5-Bromophthalazine hemihydrate

“…Moreover, they are of particular interest owing to their biological activity and optical properties (Caira, et al, 2011).…”