A facile carbene route to 2-fluoro-2-pyrrolines via fluorinated azomethine ylides

Stereochemistry of 1,3‐dipolar‐cycloaddition of 3,4‐dihydroisoquinoline‐ and 3,4‐dihydro‐carboline‐N‐methoxycarbonyl‐ and N‐phenacyl‐methylides with maleic and fumaric nitrile

“…Despite the considerable advantages of this method in the next years it was relatively sparsely applied: only Tsuge et al used it also for the preparation of isoquinolinium ylides [17], then Pota ek [18] and S iwa [19] applied it for the synthesis of phenantridinium and benzo[h]napthyridinium ylides, respectively. It is worth mentioning some other less direct synthetic routes, which were also applied for the preparation of nonstabilized cyclic azomethine ylides by Poissonnet (desylilation route [3]), and Novikov (difluoro-carbene addition route [20]) and for stabilized cyclic ylides by Grigg (dehydrogenation route [21]). The cited authors [3,[16][17][18][19][20][21] studied the 1,3-dipolar cycloaddition reactions of the so prepared cyclic azomethine ylides with activated olefines e.g.…”

Formation and reactivity of gem-difluoro-substituted pyridinium ylides: Experimental and DFT investigation

“…Obviously, the labile yellow compound is dihydroindolizine 5a, the product of dehydrofluorination of primary adduct 4a of 1,3-dipolar cycloaddition of pyridinium ylide 2a to dimethyl maleate. Dehydrofluorination of the primary cycloadduct 4a readily proceeds under the reaction conditions in the same way as in the reactions of difluorocarbene with Schiff bases [6,27,28]. Compound 3a was isolated only in poor yield (4%) that may partly be due to unselective oxidation of dihydroindolizine 5a by air oxygen during chromatographic purification.…”

A Simple Two‐Step Sequence for the Synthesis of Novel 4‐Aryl‐4,5‐dihydro‐6H‐[1,3]dioxolo[4,5‐h]pyrrolo[1,2‐a][1]benzazepin‐6‐ones from 6‐Amino‐3,4‐methylenedioxyacetophenone

“…For example, compounds 4 , obtained through an asymmetric 1,3‐dipolar reaction, showed moderate activities in several in vitro assays for adrenergic, dopaminergic and serotoninergic receptors 2a. Fluorinated compound 5 was synthesized by a 1,3‐dipolar cycloaddition domino sequence because of its potential biological activity 2b. Compounds 6 were prepared for screening as novel and selective peripheral‐type benzodiazepine receptor (PBR) ligands and to evaluate their ability to modulate steroid biosynthesis in rats 2c.…”