Mechanism of the Aza-Piancatelli Reaction: Scope and Limitations of Furan Substitution in Donor-Acceptor Stenhouse Adduct Synthesis

Beatriz Peñín; Nil Sanosa; Diego Sampedro; Ignacio Funes-Ardoiz

doi:10.1021/acsomega.2c02439

Mechanism of the Aza-Piancatelli Reaction: Scope and Limitations of Furan Substitution in Donor-Acceptor Stenhouse Adduct Synthesis

ACS Omega. 2022 Jun 16;7(26):22811-22817. doi: 10.1021/acsomega.2c02439. eCollection 2022 Jul 5.

Authors

Beatriz Peñín¹, Nil Sanosa¹, Diego Sampedro¹, Ignacio Funes-Ardoiz¹

Affiliation

¹ Departamento de Química, Centro de Investigación en Síntesis Química (CISQ), Universidad de La Rioja, Madre de Dios, 53, 26006 Logroño, Spain.

Abstract

The aza-Piancatelli reaction has been widely used to synthesize donor-acceptor Stenhouse adducts (DASAs), a new class of molecular photoswitches with unique properties. However, the substitution pattern of furan cores has been limited to position 3, as 3,4-disubstituted furans remain unreactive. Herein, we explore the aza-Piancatelli reaction mechanism using density functional theory (DFT) calculations to understand the influence of the different substituents on the reactivity. We found that all the reaction pathways are kinetically accessible, but the driving force of the reaction is lost in disubstituted furans due to the loss of conjugation in the DASA products. Finally, a simple model is proposed to guide the design of synthetic routes using this reaction.