1-Substituted 1,2,3-triazoles represents ‘privileged’ structural scaffolds of many clinical pharmaceuticals. However, the traditional methods for their preparation mainly rely on thermal [3 + 2] cycloaddition of potentially dangerous acetylene and azides. Here we report a base-mediated [4 + 1] annulation of azoalkenes generated in situ from readily available difluoroacetaldehyde N-tosylhydrazones (DFHZ-Ts) with amines under relatively mild conditions. This azide- and acetylene-free strategy provides facile access to diverse 1-substituted 1,2,3-triazole derivatives in high yield in a regiospecific manner. This transformation has great functional group tolerance and can suit a broad substrate scope. Furthermore, the application of this novel methodology in the gram-scale synthesis of an antibiotic drug PH-027 and in the late-stage derivatization of several bioactive small molecules and clinical drugs demonstrated its generality, practicability and applicability.

[4 + 1] Annulation of in situ generated azoalkenes with amines: A powerful approach to access 1-substituted 1,2,3-triazoles

Zanoni G.;
2021

Abstract

1-Substituted 1,2,3-triazoles represents ‘privileged’ structural scaffolds of many clinical pharmaceuticals. However, the traditional methods for their preparation mainly rely on thermal [3 + 2] cycloaddition of potentially dangerous acetylene and azides. Here we report a base-mediated [4 + 1] annulation of azoalkenes generated in situ from readily available difluoroacetaldehyde N-tosylhydrazones (DFHZ-Ts) with amines under relatively mild conditions. This azide- and acetylene-free strategy provides facile access to diverse 1-substituted 1,2,3-triazole derivatives in high yield in a regiospecific manner. This transformation has great functional group tolerance and can suit a broad substrate scope. Furthermore, the application of this novel methodology in the gram-scale synthesis of an antibiotic drug PH-027 and in the late-stage derivatization of several bioactive small molecules and clinical drugs demonstrated its generality, practicability and applicability.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11571/1447219
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