ASYMMETRIC SYNTHESIS OF ISOQUINUCLIDINE BY DIELS-ALDER REACTION OF 1,2-DIHYDROPYRIDINE AND CHIRAL DIENOPHILE UTILIZING A CHIRAL LEWIS ACID

摘要

The asymmetric Diels-Alder reaction of 1-phenoxycarbonyl-1,2-dihydropyridine 1 with 3-acryloyl (45)-4-benzyl-1,3-oxazolidin-2-one (4S)-2 {or (4R)-2} in the presence of Ti-TADDOLate 4 as a chiral Lewis acid afforded the chiral isoquinuclidine derivative endo-(4'S)-3 in high yield (99%) with high diastereoselectivity (up to 92% d.e.). The reaction exhibits a strong match-mismatch effect. The stereochemistry of endo-(4'S)-3 was established to be (1R, 4S,7R) and a reaction mechanism is proposed.