Allylation of active methylene compounds with cyclic Baylis–Hillman alcohols: a DFT study

• Published in: Theoretical chemistry accounts 2015-08, Vol.134 (8), Article 98
• Main Authors: Harrath, Karim, Essalah, Khaled, Morell, Christophe, Chermette, Henry, Boughdiri, Salima
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Atomic/Molecular Structure and Spectra; Chemical Sciences; Chemistry; Chemistry and Materials Science; Inorganic Chemistry; Organic Chemistry; Physical Chemistry; Regular Article; Theoretical and Computational Chemistry
• ISSN: 1432-881X; 1432-2234
• DOI: 10.1007/s00214-015-1694-7

Allylation reaction of active methylene compounds with cyclic Baylis–Hillman (BH) alcohol catalyzed by 4-dimethyamino-pyridine (DMAP) has been investigated by means of density functional theory with B3LYP/6-311++G(d,p). The first step on the chemical path is considered as an acid–base reaction. It is then followed by allylation of active methylene compound with cyclic BH alcohol. Calculated gas-phase pKa values illustrate that active methylene compounds have higher acidity than the considered cyclic BH alcohol. The DMAP catalytic activity may be interpreted as a proton transfer bridge between the active methylene compounds and the cyclic BH alcohol. Two alternative competing reactivity sites are present. Regioselectivity has been carried out on the base of natural atomic charge, Fukui index. The computations help rationalizing the fact that the direct allylation is the favored reaction and leads to the end-product.