Synthesis 2021; 53(02): 348-358
DOI: 10.1055/s-0040-1707278
paper

An Efficient Synthesis of Functionalized 2H-1,3,5-Oxadiazines via Metal-Carbenoid-Induced 1,2,4-Oxadiazole Ring Cleavage

Julia O. Strelnikova
,
,
Olesya V. Khoroshilova
,
,
Mikhail S. Novikov
Institute of Chemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russian Federation   Email: m.novikov@spbu.ru
› Author Affiliations
We gratefully acknowledge the financial support of the Russian Foundation for Basic Research (No. 18-33-00423).


Abstract

A high-yielding method for the synthesis of 2H-1,3,5-oxadiazines by rhodium(II)- or copper(II)-catalyzed reaction of 1,2,4-oxadiazoles with α-diazo esters has been developed. The reaction proceeds via attack of the metallocarbenoid on the oxadiazole N2 atom followed by ring opening/1,6-electrocyclization and enables the introduction of alkyl, aryl, oxy, and amino substituents into the 6-position and electron-withdrawing groups into the 2-position of 1,3,5-oxadiazine. The N2-attack and the N4-attack of the carbenoid cause different oxadiazole ring openings, which are controlled by the substitution at C5. The presence of a substituent at this position is a prerequisite for the N2-attack to occur, leading to the formation of 1,3,5-oxadiazines.

Supporting Information



Publication History

Received: 07 July 2020

Accepted after revision: 13 August 2020

Article published online:
29 September 2020

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