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Updated: May 23, 2025

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
Synthesis of (+)-Saxitoxin Facilitated by a Chiral Auxiliary for Photocycloadditions Involving Alkenylboronate Esters
Yang Jiao1, Jiaqi Liu1, Weijie Mao1
1Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education and Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Abstract:
(+)-Saxitoxin, a potent neurotoxin and NaV blocker, poses significant synthetic challenges due to its compact tricyclic framework and guanidinium moieties. We report a concise and asymmetric total synthesis featuring an intramolecular [2 + 2] photocycloaddition of an alkenylboronate ester equipped with a new chiral auxiliary. This auxiliary, compatible with UV light and easily exchangeable on B(pin) derivatives, enabled high stereocontrol through hydrogen-bond-mediated transition-state stabilization. Our approach not only introduces an innovative surrogate for intramolecular Michael addition, particularly addressing transformations with contra-thermodynamic barriers, but also highlights the potential of boron-enabled photochemistry for synthesizing complex molecules.
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