Construction of Saturated Oxazolo[3,2-b][1,2]oxazines via Tandem [3+2]-Cycloaddition/[1,3]-Rearrangement of Cyclic Nitronates and Ketenes

Autor:	Ivan S. Golovanov, Yulia V. Nelyubina, Alexey Yu. Sukhorukov, Sema L. Ioffe, Roman S. Malykhin
Rok vydání:	2021
Předmět:	chemistry.chemical_classification chemistry.chemical_compound Tandem Bicyclic molecule Chemistry Stereochemistry Organic Chemistry Ketene Oxazines Bond cleavage Cycloaddition Stereocenter
Zdroj:	The Journal of Organic Chemistry. 86:16337-16348
ISSN:	1520-6904 0022-3263
DOI:	10.1021/acs.joc.1c01744
Popis:	Reaction of six-membered cyclic nitronates with disubstituted ketenes affords hitherto unknown saturated oxazolo[3,2-b][1,2]oxazines possessing up to four contiguous stereogenic centers. The process involves a tandem of [3+2]-cycloaddition across the C═O bond of ketene, followed by a spontaneous [1,3]-rearrangement of transient vinylidene-substituted bicyclic nitrosoacetals. DFT calculations of the mechanism suggest that the [1,3]-O,C-shift proceeds through a recyclization of a biradical intermediate formed by an unusually mild homolytic cleavage of the N-O bond. The resulting products can be utilized as precursors of other fused 1,2-oxazines derivatives, in particular 1,2-oxazino-1,2,4-triazin-3-ones.
Databáze:	OpenAIRE
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