Catalysis with inorganic cations. VI. The effect of chiral bis-oxazoline-magnesium perchlorate catalysts on chemo- and enantioselectivity of intramolecular Hetero Diels-Alder and ene reaction
(E)1-acetyl-[2-(3-methyl-2-butenyloxy)benzylidene]indolin-2-one (1) gives competition between the intramolecularHeteroDiels-Alder (HDA) (thermal conditions) and the intramolecularenereaction (IER) (magnesiumperchlorate - MP - catalyzed conditions). Several complexes derived from MP and chiral bis-oxazolines were found to be excellent chemo- and enantioselective catalysts with a different degree
competition between HeteroDiels-Alder (HDA) and intramolecularenereaction (IER) was tested on (E)1-acetyl-3-arylideneindolin-2-one (5). Under thermal conditions HDA products 6a,b are obtained in a quantitative yield stressing the importance of the configuration of the α,β-unsaturated carbonyl system on the reactivity. Both reactivity and chemoselectivity are strongly influenced if the reaction is carried