- Employment of Nitriles in the Stereoselective Cycloaddition to Nitrones
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The cycloaddition of the nitrones 8-11 to the geminal dinitriles 12a-d has been evaluated.Under thermal as well high-pressure reaction conditions 1,3 dipolar cycloadditions proceed with complete regioselectivity to give the Δ4-1,2,4-oxadiazolin
- Plate, Ralf,Hermkens, Pedro H. H.,Smits, Jan M. M.,Nivard, Rutger J. F.,Ottenheijm, Haary C. J.
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- 1,3-Dipolar Cycloaddition of Nitrones with Nitriles. Scope and Mechanistic Study
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1,3-Dipolar cycloadditions of nitrones 1-6 with nitriles 14-16, proceeded under thermal as well as under high pressure conditions with complete regioselectivity to give Δ4-1,2,4-oxadiazolines 17-19.In general, the cycloaddition seemed to be controlled by a HOMO(nitrone)- LUMO(nitrile) interaction.However, a crossover in the orbital control is probable observed with nitrile 16c.Nitrone-nitrile cycloadditions are normal type II cycloadditions so that the nitriles have a U-shaped reactivity curve.Kinetic study on solvent polarity and Hammett equation demonstrated that mechanistically the nitrone-nitrile cycloaddition is consistent with nitrone-alkene cycloaddition.
- Hermkens, Pedro H.H.,Maarseveen, Jan H. v.,Kruse, Chris G.,Scheeren, Hans W.
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p. 6491 - 6504
(2007/10/02)
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