Bell-Tyrer JJ, Hume PA, Grant PS, Brimble MA, Furkert DP. Azide-Enolate Cycloaddition-Rearrangement Enables Direct α-Amination of Amides and Enelactam Synthesis from Esters.
Chemistry 2023:e202300261. [PMID:
36849870 DOI:
10.1002/chem.202300261]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 02/22/2023] [Accepted: 02/24/2023] [Indexed: 03/01/2023]
Abstract
Azide-enolate cycloaddition-rearrangements offer potential for rapid access to diverse molecular frameworks, from simple precursors. We report here that investigations into the cycloadditions of ester or amide enolates with vinyl azides led to the identification of two reaction processes - direct α-amination of amides and lactams, and synthesis of ene-γ-lactams from esters. These reaction outcomes depended on the fate of key vinyl triazoline intermediates generated in the initial cycloaddition step. Isolation of reaction intermediates in the ene-g-lactam synthesis revealed the unexpected addition of two enolate equivalents, one of which is later eliminated. Computational studies further suggested an unusual reaction pathway involving direct addition of an enolate to the terminal carbon of the N-vinyl triazoline. In contrast, the α-amination of amides and lactams proceeded by rearrangement of the intermediate triazoline to give an imine, hydrolysis or reduction of which gave access to primary or secondary α-amino amides or lactams.
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