2-[(1E,3E)-4-Arylbuta-1,3-dien-1-yl]-4H-chromen-4-ones as Dienes in Diels-Alder Reactions - Experimental and Computational Studies

• Tipo: Artigo em Revista Científica Internacional
• Data: 2017

Autores

Albuquerque, HMT (Autor) Outra; Santos, CMM (Autor) Outra; Lima, CFRAC (Autor) FCUP; Luis M N B F Santos (Autor) FCUP; Cavaleiro, JAS (Autor) Outra; Silva, AMS (Autor) Outra

Revista

Título: European Journal of Organic Chemistry

Vol. 2017

Páginas: 87-101

ISSN: 1434-193X

Editora: Wiley-Blackwell

Indexação

ISI Web of Knowledge - 6 Citações

Scopus - 6 Citações

Outras Informações

ID Authenticus: P-00M-G73

DOI: 10.1002/ejoc.201601072

Abstract (EN): The synthesis and reactivity of 2-[(1E,3E)-4-arylbuta1,3-dien-1-yl]-4H-chromen-4-ones as dienes in Diels-Alder (DA) reactions with several electron-poor and electron-rich dienophiles under microwave irradiation was studied. The optimized reaction conditions were achieved with N-methylmaleimide as the dienophile and Sc(OTf)3 (OTf = triflate) as a Lewis acid under microwave-assisted and solvent-free conditions. The Lewis acid improved the reaction yields as it prevented the adducts obtained from undergoing a second DA reaction; thus, the for-mation of a bisadduct was avoided. The alpha,beta,gamma,delta-diene of the starting chromones was the most reactive, and the computational results confirmed the experimental findings. Theoretical calculations also provided a rationale for the unexpected lack of reactivity shown by some dienophiles. The adducts prepared were dehydrogenated with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ); however, the aza adducts were sensitive to the highly energetic reaction conditions necessary for the aromatization.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 15