The copper catalyzed radical cyclization (RC) of N-α-perchloroacyl cyclic ketene-N,X(X = O, NR, S)-acetals was studied. While the RC of N-acyl ketene-N,O-acetals was unsuccessful, the 5-endo cyclization provided much better results, with the following order of cyclization efficiency: hexa-atomic cyclic ketene-N,NR-acetals < penta-atomic cyclic ketene-N,S-acetals < hexa-atomic cyclic ketene-N,S-acetals. Invariably the catalytic cycle begins with the formation of a carbamoyl methyl radical. This leads to a cascade of reactions, including a radical polar crossover step, which ends with the formation of the maleimide nucleus, or precursors of this. Products from the RC of the hexa-atomic cyclic ketene-N,S-acetals, were efficiently transformed into disubstituted maleic anhydrides.

CuCl catalyzed radical cyclisation of N-alpha-perchloroacyl-ketene-N,S-acetals: a new way to prepare disubstituted maleic anhydrides / Cornia, Andrea; F., Felluga; V., Frenna; Ghelfi, Franco; A. F., Parsons; M., Pattarozzi; Roncaglia, Fabrizio; D., Spinelli. - In: TETRAHEDRON. - ISSN 0040-4020. - STAMPA. - 68:(2012), pp. 5863-5881. [10.1016/j.tet.2012.04.117]

CuCl catalyzed radical cyclisation of N-alpha-perchloroacyl-ketene-N,S-acetals: a new way to prepare disubstituted maleic anhydrides

CORNIA, Andrea;GHELFI, Franco;RONCAGLIA, Fabrizio;
2012

Abstract

The copper catalyzed radical cyclization (RC) of N-α-perchloroacyl cyclic ketene-N,X(X = O, NR, S)-acetals was studied. While the RC of N-acyl ketene-N,O-acetals was unsuccessful, the 5-endo cyclization provided much better results, with the following order of cyclization efficiency: hexa-atomic cyclic ketene-N,NR-acetals < penta-atomic cyclic ketene-N,S-acetals < hexa-atomic cyclic ketene-N,S-acetals. Invariably the catalytic cycle begins with the formation of a carbamoyl methyl radical. This leads to a cascade of reactions, including a radical polar crossover step, which ends with the formation of the maleimide nucleus, or precursors of this. Products from the RC of the hexa-atomic cyclic ketene-N,S-acetals, were efficiently transformed into disubstituted maleic anhydrides.
2012
68
5863
5881
CuCl catalyzed radical cyclisation of N-alpha-perchloroacyl-ketene-N,S-acetals: a new way to prepare disubstituted maleic anhydrides / Cornia, Andrea; F., Felluga; V., Frenna; Ghelfi, Franco; A. F., Parsons; M., Pattarozzi; Roncaglia, Fabrizio; D., Spinelli. - In: TETRAHEDRON. - ISSN 0040-4020. - STAMPA. - 68:(2012), pp. 5863-5881. [10.1016/j.tet.2012.04.117]
Cornia, Andrea; F., Felluga; V., Frenna; Ghelfi, Franco; A. F., Parsons; M., Pattarozzi; Roncaglia, Fabrizio; D., Spinelli
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/738458
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