Quinolizidines. XXV. : An Extension of the "Lactim Ether Route" to the Racemic Syntheses of Several Indolo[2, 3-α]quinolizidine Alkaloids

Abstract

The "lactim ether route, " originally designed for unified racemic and chiral syntheses of the benzo[a]quinolizidine-type Alangium alkaloids, has been extended to cover the racemic syntheses of several indolo[2, 3-a]quinolizidine alkaloids (1 and 8c, d). The synthetic routes started from the lactams 5a, b and proceeded smoothly through the lactim ethers 6a, b, lactam ketones 7a, b, lactam alcohols 10a, b, and N-substituted lactams 9a, b.