Boron‐Promoted Ether Interchange Reaction: Synthesis of Alkyl Nitroaromatic Ethers from Methoxynitroarenes

Abstract

The first protocol for boron‐promoted ether interchange reaction of methoxynitroarenes was described. A series of methoxynitroarenes and alcohols, including primary, secondary, as well as tertiary alcohols were reacted smoothly in moderate to good yields under the optimized reaction conditions. This protocol constitutes an operationally simple and scalable strategy for the synthesis of alkyl nitroaromatic ethers. Moreover, the new reactivity of boron reagents was discovered.

Emergent Organoboron Acid Catalysts

“…The Kürti group developed the combination of an electron-poor arylboronic acid catalyst and allylboronic esters as nucleophilic species in the allylation of oximes, though they do not propose a mechanistic role for the catalyst (Scheme ). Wu, Wu, Zou, and co-workers reported on an ether interchange reaction of methoxynitroarenes catalyzed by various organoboron species . They proposed a boron-mediated nucleophilic aromatic substitution mechanism to explain the observed reactivity, resulting in the exchange of an alkoxy group on the boron for the methoxy group on the arene (Scheme ).…”

“…Wu, Wu, Zou, and co-workers reported on an ether interchange reaction of methoxynitroarenes catalyzed by various organoboron species. 119 They proposed a boron-mediated nucleophilic aromatic substitution mechanism to explain the observed reactivity, resulting in the exchange of an alkoxy group on the boron for the methoxy group on the arene (Scheme 32). Dixon and co-workers reported on a carbocyclization of ketoesters to a pendant terminal alkyne through the boronic acid catalyzed enolization of the ketoester and subsequent ene reaction to produce a variety of five-membered rings (Scheme 33).…”