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

Abstract

Synthesis of 2-aminofuran derivatives with azulene or N,N-dimethylanilino substituent was established by the formal [2 + 2] cycloaddition-retroelectrocyclization of 3-(1-azulenyl or N,N-dimethylanilino)-2-propyn-1-ols with tetracyanoethylene, followed by the intramolecular nucleophilic addition to the initially formed tetracyanobutadiene moiety of the internal hydroxyl group that come from 2-propyn-1-ol. The reaction proceeds under mild conditions with short reaction period. The products of the reaction are readily available with simple purification procedure. 2-Aminofuran derivatives obtained by this reaction were revealed to be convertible to 6-aminofulvene derivatives with the treatment of various amines. The structure of 2-aminofuran and 6-aminopentafulvene with N,N-dimethylanilino substituent was confirmed by single crystal X-ray structural analysis.

The [2+2] Cycloaddition‐Retroelectrocyclization (CA‐RE) Click Reaction: Facile Access to Molecular and Polymeric Push‐Pull Chromophores

“…However,when the TCBD or extended TCNQ units from the CA-RE reactions were directly attached to the allene moiety,a4 p-electrocyclization between the allene core and the proximal dicyanovinyl moiety proceeded under mild heating conditions.F or example,T CBD (AE)-111 could be transformed into cyclobutene derivative 112 in about 60 %yield (Scheme 15). [97] 6. [96] Recently,t he CA-RE-initiated cascade reaction from donor-substituted 2-propyn-1-ols and TCNE to yield 2-aminofuran derivatives was also reported.…”

Azulene‐Based Donor–Acceptor Systems: Synthesis, Optical, and Electrochemical Properties

“…Table 5. [62] As illustrated in Scheme 8, the formation of aT CBD intermediate was expected upon reaction of 54 with TCNE. When the spectral changes of bis-TCBD 52 were measured under electrochemical reduction conditions, an ew absorption band at around 635 nm developed and extended into the near-infrared region, owing to the generation of anionic species of 52.R everse oxidation resulted in ad ecrease in the new absorption band, along with the recovery of the originals pectrum of 52.S imilart ob is-1-AzTCBD 5,t he reversible color changes of 52 were attributed to the violene-cyanine-violene moiety.…”

Molecular Transformation to Pyrroles, Pentafulvenes, and Pyrrolopyridines by [2+2] Cycloaddition of Propargylamines with Tetracyanoethylene

“…The field of chemistry has been progressed by Diederich, [2] Michinobu, [3] Trolez, [4] Misra [5] and our group. [7] Based on the results of theses tudies, we envisioned the preparation of highly functionalized pyrrole derivatives by the reaction of the propargylamines with TCNE (Scheme 1). [7] Based on the results of theses tudies, we envisioned the preparation of highly functionalized pyrrole derivatives by the reaction of the propargylamines with TCNE (Scheme 1).…”

“…[7] We explored the scope of the reactionb yt reating propargylamines 1b-1j with TCNE. [7] We explored the scope of the reactionb yt reating propargylamines 1b-1j with TCNE.…”

“…[13] As am etal free-synthesis, Diederich et al have reported the [2+ +2] CA-RE reaction of TCBD derivatives with electron-richa lkynes and subsequentt reatment with ceric ammonium nitrate to give cyano-polysubstituted pentafulvened erivatives. [7] However,t here is no literaturer eporting the more direct synthesis of pentafulvene derivatives starting from propargylamines or TCNE derivatives, which are both readily available materials. [7] However,t here is no literaturer eporting the more direct synthesis of pentafulvene derivatives starting from propargylamines or TCNE derivatives, which are both readily available materials.…”