Cycloaddition of Huisgen 1,4-dipoles: synthesis and rapid epimerization of functionalized spiropyrido[2,1-][1,3]oxazine-pyrroles and related products

1,4-Dipolar cycloaddition has emerged as a powerful tool for the synthesis of various cyclic compounds. In the present work, 1 H -pyrrole-2,3-diones are proposed as new dipolarophiles for 1,4-dipolar cycloaddition. Their [4 + 2] cycloaddition with dipoles generated from dimethyl acetylenedicarboxyla...

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Bibliographic Details
Published in:RSC advances 2021-12, Vol.12 (1), p.578-587
Main Authors: Galeev, Andrew R, Moroz, Anna A, Dmitriev, Maksim V, Maslivets, Andrey N
Format: Article
Language:English
Subjects:
Chemistry
Cyclic compounds
Cycloaddition
Diketones
Dipoles
Pyrroles
Synthesis
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Summary:1,4-Dipolar cycloaddition has emerged as a powerful tool for the synthesis of various cyclic compounds. In the present work, 1 H -pyrrole-2,3-diones are proposed as new dipolarophiles for 1,4-dipolar cycloaddition. Their [4 + 2] cycloaddition with dipoles generated from dimethyl acetylenedicarboxylate and pyridine was found to proceed regioselectively affording spiro[pyrido[2,1- b ][1,3]oxazine-2,3′-pyrroles] as diastereomeric mixtures which exist in rapid equilibrium in solution. It was established that this phenomenon of rapid epimerization is a characteristic of other similar spiropyrido[2,1- b ][1,3]oxazines and even related spiroquinolizines, which was demonstrated by the investigation of related products of previously reported, and reproduced in this work, 1,4-dipolar cycloaddition reactions. Rapid epimerization of cycloadducts from Huisgen 1,4-dipoles has been investigated through the synthesis of new spiropyrido[2,1- b ][1,3]oxazine-pyrroles and repetition of syntheses from the literature.
ISSN:2046-2069
2046-2069
DOI:10.1039/d1ra08384h