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

• Type: Article in International Scientific Journal
• Date: 2017

Authors

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

Journal

Title: European Journal of Organic Chemistry

Vol. 2017

Pages: 87-101

ISSN: 1434-193X

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 6 Citations

Scopus - 6 Citations

Other information

Authenticus ID: 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.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 15