The complete path of the Brandi-Guarna rearrangement of 5-spirocyclopropane isoxazolidines has been investigated by means of density functional theory calculations to rationalize the competing formation of tetrahydropyridones and enaminones by the determination of the minimum energy reaction paths. Our calculations confirm that the rearrangement is triggered by the homolysis of the isoxazolidine N-O bond followed by cleavage of one of the two C-CH2 cyclopropane bonds as previously proposed by the Fabian group [Eur. J. Org. Chem. 2001, 2001, 4223]. In addition, the results of this work suggest that in the presence of a stereogenic center at isoxazolidine C-4′, the formation of a piperidinone or an enaminone as the final product depends on which of the two diastereotopic C-CH2 bonds of cyclopropane is cleaved in the second step of the process. The result can be of great interest for the understanding of other processes involving the opening of a cyclopropane ring.

Computational Investigation of the Selective Cleavage of Diastereotopic Cyclopropane Bonds in 5-Spirocyclopropane Isoxazolidines Rearrangement / Briccolani-Bandini L.; Brandi A.; Cardini G.; Chelli R.; Cordero F.M.; Gellini C.; Pagliai M.. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - STAMPA. - 84:(2019), pp. 6757-6764. [10.1021/acs.joc.9b00499]

Computational Investigation of the Selective Cleavage of Diastereotopic Cyclopropane Bonds in 5-Spirocyclopropane Isoxazolidines Rearrangement

Briccolani-Bandini L.;Brandi A.;Cardini G.;Chelli R.;Cordero F. M.;Gellini C.;Pagliai M.
2019

Abstract

The complete path of the Brandi-Guarna rearrangement of 5-spirocyclopropane isoxazolidines has been investigated by means of density functional theory calculations to rationalize the competing formation of tetrahydropyridones and enaminones by the determination of the minimum energy reaction paths. Our calculations confirm that the rearrangement is triggered by the homolysis of the isoxazolidine N-O bond followed by cleavage of one of the two C-CH2 cyclopropane bonds as previously proposed by the Fabian group [Eur. J. Org. Chem. 2001, 2001, 4223]. In addition, the results of this work suggest that in the presence of a stereogenic center at isoxazolidine C-4′, the formation of a piperidinone or an enaminone as the final product depends on which of the two diastereotopic C-CH2 bonds of cyclopropane is cleaved in the second step of the process. The result can be of great interest for the understanding of other processes involving the opening of a cyclopropane ring.
2019
84
6757
6764
Briccolani-Bandini L.; Brandi A.; Cardini G.; Chelli R.; Cordero F.M.; Gellini C.; Pagliai M.
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1160144
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