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Updated: Feb 10, 2026

Functionalized Spirocyclic Heterocycle Synthesis and Cytotoxicity Assay
Published on: February 9, 2021
Organocatalytic synthesis of densely functionalized oxa-bridged 2,6-epoxybenzo[b][1,5]oxazocine heterocycles
Ramani Gurubrahamam1, Koppanathi Nagaraju, Kwunmin Chen
1Department of Chemistry, National Taiwan Normal University, 88, Sec. 4, Tingchow Road, Taipei 11677, Taiwan, Republic of China. kchen@ntnu.edu.tw.
Abstract:
Metal-free addition of salicylhydrazones to electron deficient internal alkynes catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) to yield oxa-bridged 2,6-epoxybenzo[b][1,5]oxazocine heterocycles was achieved. The demonstrated protocol proceeds through an o-quinone methide formation, aza-Michael addition, stereoselective protonation, enamine promoted aromatization, O,O-acetalization and O,N-aminalization sequence to provide privileged heterocycles in good yields with high diastereoselectivities.
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