Phosphane‐Catalyzed [3+2] Annulation of Allenoates with 3‐Nitro‐2H‐chromenes: Synthesis of Tetrahydrocyclopenta[c]chromenes

Abstract

The synthesis of carbocyclic‐fused chromene derivatives based on allene chemistry is described. The phosphane‐catalyzed [3+2] annulation reactions of allenic esters with 3‐nitrochromenes have been established affording 3a‐nitro‐tetrahydrocyclopenta[c]chromenes in good yields (up to 87 %) with high stereo‐ and regioselectivity. Quantum chemical calculations, carried out at the DFT level of theory, were in agreement with the observed selectivity. The trichlorosilane‐mediated reduction of the 3a‐nitro‐tetrahydrocyclopenta[c]chromenes into the corresponding amines is also reported.

Recent Advances of Michael/hetero‐Michael Addition Reaction in the Synthesis of 3‐Nitro‐2H‐chromene Derivatives

“…The plausible mechanism is depicted in Scheme 11. [56] In addition, dibenzo[b,d]furan derivatives are an important core due to their wide occurrence in various bioactive drugs Then, by elimination of pyridine and a proton produced E which undergoes resonance hybrid to afford F. Then intramolecular addition of carbanion to carbonyl group afforded G, which upon aromatization gave H. Finally, the nucleophilic substitution of phenoxide ion to nitro group produced the final product 43 (Scheme 12). [57] Viewing the synthetic utility and importance of carbocyclic or heterocyclic fused 2-aryl-3-nitro-2H-chromenes, in 2020, The mechanism is depicted in scheme 13.…”

Efficient synthesis of 4‐phenacylideneflavenes using recyclable gelified Brønsted acidic ionic liquid under solvent‐free and column chromatography‐free conditions: a green method and mechanistic insight

“…Indeed, there is a legion of reports investigating the natural limitation of the aforementioned pathways, such as the use of abundant amounts of strong organic/inorganic acid/base, problematic isolation process, toxic transition metals with high catalyst loading, solvent-dependent reactions, and environment-dependent catalysts such as light, air and moisture. [5][6][7][8][9] Even under the most neoteric sets of conditions, archived and anecdotal evidence still exists that the synthesis of the benzopyran framework remains an enduring challenge in terms of conditions and substrates. Ionic liquids have received significant attention for their application as solvents/catalysts for organic transformation because of their unique physical and chemical properties.…”

Construction of cyclopentane-fused coumarins via DBU-catalyzed [3+2] cycloaddition of 3-homoacyl coumarins with cyclic 1-azadienes

“…1 ). 4 Not surprisingly, the strategies for synthesis of cyclopentane-fused coumarins have attracted much attention. 5 …”