Concise syntheses of GB22, GB13 and himgaline by cross-coupling and complete reduction

Abstract

Class III neuroactive metabolites from the bark of Galbu-limima belgraveana occur in variable distribution and are not easily procured by chemical synthesis. Here we decrease the synthetic burden of himgaline to nearly one-third of the prior best (7–9 vs. 19–31 steps) by cross-coupling high fraction aromatic (FAr) building blocks followed by com-plete, stereoselective reduction to high-fraction sp3 (Fsp3) products. This short entry into GB alkaloid space allows its extensive exploration and biological interrogation.

Catalysis-Enabled 13-Step Total Synthesis of (−)-Peyssonnoside A

“…Additionally, these new catalytic capabilities allowed us to use readily available and cheap starting materials with a high fraction of sp 2 /sp carbons to synthesize products with a high percentage of sp 3 carbons and significantly increased structural complexity. 14 This concise synthesis also demonstrated how modern catalysis can impact and facilitate the total synthesis of complex natural products.…”