Remarkable influence of mild Lewis acid catalysts on cycloadditions leading to tetrasubstituted isoxazolidines: DFT analysis augmented by X-ray and NMR studies

• Published in: Monatshefte für Chemie Vol. 143; no. 12; pp. 1687 - 1703
• Main Authors: Acharjee, Nivedita, Banerji, Avijit, Prangé, Thierry
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.12.2012; Springer Nature
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Chemistry, Multidisciplinary; Chemistry/Food Science; Inorganic Chemistry; Organic Chemistry; Original Paper; Physical Chemistry; Physical Sciences; Science & Technology; Theoretical and Computational Chemistry; Transition states; Density functional theory; Catalysis; Interaction energy; ENERGY; ELECTROPHILICITY; NITRONES; REACTIVITY; REGIOSELECTIVITY; YLIDES; MOLECULES; DIELS-ALDER REACTION; 1,3-DIPOLAR CYCLOADDITION; HARDNESS
• ISSN: 0026-9247; 1434-4475
• DOI: 10.1007/s00706-012-0828-z

Experimental and theoretical studies were carried out to highlight the influence of mild Lewis acid catalysts on the cycloadditions leading to stereochemically defined tetrasubstituted isoxazolidines. Considerable acceleration and increased exo stereoselectivity were observed for lithium triflate and magnesium bromide catalyzed processes. DFT-based reactivity indices reflected the differences in polar character of the catalyzed and uncatalyzed pathways. The regioselectivities were predicted from interaction energy calculations. Finally, the transition states were successfully located and the extent of bond formation analyzed. The catalytic acceleration was rationalized by density functional theory (DFT) calculated activation parameters. The rate constant ratios with Eyring’s transition state theory (TST) rate equation and total partition functions were also theoretically evaluated to further rationalize the observed catalytic acceleration. Graphical abstract