Stereoselective synthesis of the pyrrolizidine alkaloids (-)-integerrimine and (+)-usaramine

JD White, JC Amedio Jr, S Gut, S Ohira…

Index: White, James D.; Amedio, John C.; Gut, Samuel; Ohira, Susumu; Jayasinghe, Lalith R. Journal of Organic Chemistry, 1992 ,  vol. 57,  # 8  p. 2270 - 2284

Full Text: HTML

Citation Number: 39

Abstract

Two routes to the pyrrolizidine alkaloid (-)-integerrimhe (1) are described. The first, starting from methyl (R)-(-)-3-hydroxy-2-methylpropionate, proceeded in 19 steps to integerrinecic acid lactone (5) which was transformed to the necic acid derivative 30. The latter was coupled to protected retronecine 31, and the synthesis of 1 was completed by lactonization employing Vedejs' protocol. A second, shorter synthesis of (-)-1 was accomplished via 5, ...