Synthesis 2022; 54(02): 369-377
DOI: 10.1055/a-1623-2333
feature

Facile Access to Triazole-Fused 3,1-Benzoxazines Enabled by Metal-Free Base-Promoted Intramolecular C–O Coupling

Stepan S. Tatevosyan
,
Yury N. Kotovshchikov
,
Gennadij V. Latyshev
,
Nikolay V. Lukashev
,
Irina P. Beletskaya
The research was funded by the Russian Foundation for Basic Research and Moscow City Government (grant number 21-33-70017). NMR equipment used in this study was purchased under the M. V. Lomonosov Moscow State University Program of
Development.


In memory of Professor Ei-ichi Negishi (1935–2021).

Abstract

A convenient approach to assemble 1,2,3-triazole-fused 4H-3,1-benzoxazines has been developed. Diverse alcohol-tethered 5-iodotriazoles, readily accessible by a modified protocol of Cu-catalyzed (3+2)-cycloaddition, were utilized as precursors of the target fused heterocycles. The intramolecular C–O coupling proceeded efficiently under base-mediated transition-metal-free conditions, furnishing cyclization products in yields up to 96%. Suppression of the competing reductive cleavage of the C–I bond was achieved by the use of Na2CO3 in acetonitrile at 100 °C. This practical and cost-effective procedure features a broad substrate scope and valuable functional group tolerance.

Supporting Information



Publikationsverlauf

Eingereicht: 07. Juli 2021

Angenommen nach Revision: 30. August 2021

Accepted Manuscript online:
30. August 2021

Artikel online veröffentlicht:
12. Oktober 2021

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