Asymmetric diels-alder reactions catalyzed by chiral oxazaborolidines. Effect of the position of an electron-donor functionality in the α-side chain substituent on the enantioselectivity

Abstract

Abstract Asymmetric Diels-Alder reactions of cyclopentadiene with methacrolein and 2-bromoacrolein catalyzed by chiral oxazaborolidines 1 derived from N-tosyl-L-α-amino acids afforded cycloadducts in quantitative yield. Variation in the position of an electron donor atom in the α-side chain substituent shows that enantioselectivity is controlled by the presence of electron donor atoms in position 2 and 4.