Multicomponent Cascade Cycloaddition Involving Tropone, Allenoate, and Isocyanide: A Rapid Access to a 7,6,5-Fused Tricyclic Skeleton

Abstract

Multicomponent cascade cycloaddition of tropone, allenoate, and isocyanide has been disclosed. This method allows for the rapid construction of a highly unusual tricyclic skeleton in an efficient manner. The proposed transformation proceeds through [8 + 2 + 1] cycloaddition, [1,5]-H shift, and cyclization followed by an alkoxy group migration process.

Isocyanide-based multicomponent reactions in the synthesis of heterocycles

“…Li, Jia and coworkers reported efficient synthesis of a series of tricyclic heterocyclic framework 104 through three-component tandem cycloaddition between isocyanide 105, allenoate derivatives 106 and tropone 107 under reflux condition in toluene (Scheme 22) 156 . The protocol showed excellent substrate scope and allenoate derivatives with various electro-donating and electron-withdrawing groups could furnish the desired products.…”

Recent advances in the discovery and design of multicomponent reactions for the generation of small-molecule libraries

“…45 (D) Tandem MCR/rearrangements/cyclization strategy. 46 the palladium source. The one-pot process was realized via the removal of methanol solvent after the first reaction step, followed by the addition of acetonitrile and the components of the Pd-catalytic system (Pd 2 dba 3 , Me-phos, Cs 2 CO 3 ) into the crude reaction mixture to afford the target heterocycles in good yields.…”

“…A synthetic process based on an initial condensation of isocyanides with 1,2-disubstituted allenoates and tropolone was recently described (reaction D; Figure 6). 46 The product A (Figure 6) of the three-component coupling engaged in a series of cyclization/H-shifts/cyclization/Hshift cascade events in situ, yielding the terminal tricyclic heterocycles. The substitution patterns of the heterocycles could be diversified at three distinct positions.…”

Fe(III)-Catalyzed Bicyclization of Yne-Allenones With Indoles for the Atom-Economic Synthesis of 3-Indolyl Cyclobutarenes

“…Specifically, bicyclization cascades have emerged as an important platform for the synthesis of bioactive small-molecule libraries for their SAR studies (Dömling et al, 2012; Brauch et al, 2013; Vlaar et al, 2013; Koopmanschap et al, 2014; Rotstein et al, 2014; Huang et al, 2018b). Due to their annulation efficiency, economic and environmental aspects, and ease of operation as well as diminished waste disposals (Jia et al, 2014; Su et al, 2014; Tian et al, 2015; Chen et al, 2017; Huang et al, 2017; Liu et al, 2017b,c; Wang L. et al, 2017). In view of the environmental awareness of the chemical community, the combination of the presented bicyclization strategy and the use of environmentally benign solvents will furnish the transformations under avoidance of potential pollutants (Bihani et al, 2013; Wang J.-Y.…”