Iodine‐Promoted Domino Reactions of 1‐Cyanocyclopropane 1‐Esters: A Straightforward Approach to Fully Substituted 2‐Aminofurans

Abstract

As traightforward ande fficienti odine-promoted ring-opening/cyclization domino reaction of 1-cyanocyclopropane 1-esters for the synthesiso ff ully substituted 2-aminofurans is reported. This reaction involvest he sequential ring-opening/intramolecular cyclization reactiono f1 -cyanocyclopropane 1-esters to give the corresponding 2-amino-4,5-dihydrofurans, which were oxidized with I 2 and Et 3 Ni nr efluxing toluene to give the corresponding 2-amino-3-furancarboxylates.

Synthesis of 2‐Aminofurans by Sequential [2+2] Cycloaddition–Nucleophilic Addition of 2‐Propyn‐1‐ols with Tetracyanoethylene and Amine‐Induced Transformation into 6‐Aminopentafulvenes

“…As a modern procedure, transition‐metal‐catalyzed reactions have been employed to construct the 2‐aminofuran with various substituents . More recently, Wang and co‐workers have demonstrated the synthesis of 2‐aminofurans by iodine‐mediated sequential ring opening–cyclization domino reaction of 1‐cyanocyclopropane in good yields . Although these procedures have undoubtedly contributed to the development of 2‐aminofuran synthesis, the requirement for expensive transition‐metal catalyst and/or difficulty in the preparation of the precursor remains an issue for the preparation of 2‐aminofuran derivatives.…”

Efficient Preparation of 2,3-Disubstituted Cyclopropane-1-Carbonitriles via Selective Decarboxylation of 1-Cyanocyclopropane-1-Carboxylates

“…When the amount of iodine was reduced from 1.0 equiv., to 0.4 equiv., an obvious decrease in the product yield was observed ( Ref. 22 this work Scheme 1 Different I 2 -promoted reactions of 1-cyanocyclopropane-1-carboxylates. entry 5).…”

“…All these facts have inspired us to study the decarboxylation reactions of 2-aroyl-3-aryl-1-cyanocyclopropane-1-carboxylates, which have not been studied before, for the formation of 1,2,3-trisubstituted cyclopropane with a cyano group as a precursor of the aminomethylcyclopropane skeleton. Recently, in our investigations of the reaction conditions of the iodine-promoted ring-opening-cyclisation domino reaction of 1-cyanocyclopropane 1-esters to form fully substituted 2-aminofurans 22 (Scheme 1), we found an unexpected byproduct 2-aroyl-3-arylcyclopropane-1-carbonitrile via selective removal of the ester when the reaction solvent toluene was replaced with a mixture of DMF and toluene in the absence of water. These results impelled us to study the transformations of the title cyclopropanes to directly prepare 2,3-disubstituted cyclopropane-1-carbonitriles (Scheme 1).…”

Donor–Acceptor Cyclopropanes as an Expedient Building Block Towards the Construction of Nitrogen‐Containing Molecules: An Update

“…Numerous medicinally active compounds have been reported in the recent past having a furan or isoxazole core . Wang and co‐workers, in 2016, reported the iodine‐promoted [4+1] cycloaddition reaction of 1‐cyanocyclopropane 1‐esters 41 with water to access fully functionalized 2‐aminofuran derivatives 48 in moderate to good (63–86%) yield . The reaction proceeds via the sequential ring‐opening/cyclization reaction of 2‐aroyl‐3‐aryl‐1‐cyanocyclopropane carboxylates 41 with water to give the corresponding 2‐amino‐4,5‐dihydrofurans, which were further oxidized to the targeted 2‐amino‐3‐furancarboxylates 48 with I 2 in the presence of triethylamine (Et 3 N) under reflux conditions in toluene (Scheme ).…”