Nickel(II)-katalysierte Pyrrolsynthese aus 2H-Azirinen und aktivierten Ketonen

Abstract

Eine neue Pyrrolsynthese, die ohne Nebenreaktionen abläuft, geht von Azirinen (1) und Ketonen (2) aus. Bei genügender Aktivierung von (2) führt sie bereits bei Raumtemperatur in sehr hohen Ausbeuten zu den Pyrrolen (3).

2H-Azirines as Synthetic Tools in Organic Chemistry

“…The synthesis of metal‐coordinated 2 H ‐azirines and the reactions of azirines induced by metals have opened a new area in the chemistry of this small‐ring heterocycle. Transition metal complexes were obtained by the reaction of azirine with palladium reagents81 or with transition metal halides 82. Hegedus et al reported an elegant synthesis of electron‐rich 2‐azadienes 58 when aryl‐2 H ‐azirines react with Fischer carbenes83 57 (Scheme ).…”

Catalysts-Controlled Roles Exchange between 2,3-Diaryl-2H-azirines and Acetone: Chemodivergent Synthesis of Pyrroles and 3-Oxazolines

“…In general, they serve as the 1,3-dipole to cause cycloaddition reactions in the presence of noble metals, Lewis acids, or photocatalysts, giving various azaheterocycles, including pyrrole and 3-oxazoline. Pyrroles are synthesized from the domino reactions of 2 H -azirines and alkynes, ketones, and another molecule of 2 H -azirines . Remarkably, among these processes, the domino reactions between 2 H -azirines and ketones exhibited advantages of mild conditions and step-economic.…”

Synthesis of densely functionalize pyrroles from unprotected carbohydrates

“…This -CXN functionality appears in many drugs and drug candidates (Figure 5-1). 71,72,74,184,208,209 Previous efforts to synthesize 3-cyanopyrroles include (i) the nickel(II) bis(acetylacetonate)-catalyzed reaction between azirines and active methylene compounds reported in 1977 (Figure 5-2, i); 210 (ii) the reaction between 1-nitro-1-cyclopropyl ketones and primary amines followed by oxidizing the formed dihydropyrroles using 2,3-dichloro-5,6dicyano-1,4-benzoquinone (DDQ) to give the desired pyrroles (Figure 5-2, ii); 211 and (iii) the reaction between α-hydroxyketones, malononitrile and primary amines (Figure 5-2, iii). 212 However, the first two reactions require extra steps to prepare the complex starting materials, use metals to catalyze the reactions, and are multistep syntheses.…”