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A sequential cycloaddition strategy for the synthesis of Alsmaphorazine B traces a path through a family of Alstonia alkaloids
- Hong, Allen Y., Vanderwal, Christopher D.
- Tetrahedron 2017 v.73 pp. 4160-4171
- Alstonia, aldehydes, biosynthesis, chemical reactions, chemical structure, indole alkaloids
- Driven by a new biogenetic hypothesis, the first total synthesis of alsmaphorazine B and several related indole alkaloids has been achieved. Numerous early approaches proved unsuccessful owing to unproductive side reactivity; nevertheless, they provided important clues that guided the evolution of our strategy. Critical to our success was a major improvement in our Zincke aldehyde cycloaddition strategy, which permitted the efficient gram-scale synthesis of akuammicine. The sequential chemoselective oxidations of akuammicine leading up to the key oxidative rearrangement also yielded several biogenetically related indole alkaloids en route to alsmaphorazine B.