Asymmetric 1,3-Dipolar Cycloadditions of Nitrones and Methacrolein Catalyzed by Chiral Bis-Titanium Lewis Acid: A Dramatic Effect of N-Substituent on Nitrone

摘要

Highly stereoselective 1,3-dipolar cycloadditions of methacrolein and nitrones could be realized by the use of bis-titanium chiral Lewis acid catalyst. Key to the success is the introduction of bulky N-substituent on nitrone to attenuate the undesired Lewis acid-nitrone complexation.