Nolasco-Hernández Á, Quintero L, Cruz-Gregorio S, Sartillo-Piscil F. β-Alkenylation of Saturated
N-Heterocycles via a C(sp
3)-O Bond Wittig-like Olefination.
J Org Chem 2024;
89:1762-1768. [PMID:
38215398 PMCID:
PMC10845111 DOI:
10.1021/acs.joc.3c02466]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/17/2023] [Accepted: 12/29/2023] [Indexed: 01/14/2024]
Abstract
Although the C-Hα functionalization of N-heterocycles is, in fact, an easy chemical transformation, the C-Hβ functionalization is, on the contrary, a quite difficult chemical process. Here, we present a two-step protocol that allows the ready conversion of pyrrolidines, piperidines, and an azepane into their corresponding 3-exo-alkenyl lactams via the transient formation of 3-alkoxyamino lactams followed by a Wittig-like C(sp3)-O bond olefination with stabilized ylides from phosphonium salts mediated by t-BuOK. Additionally, as a proof of the synthetic effectiveness of this novel methodology, the first synthesis of the natural product callylactam A was achieved through a TiCl4-catalyzed double bond isomerization of a 3-exo-alkenyl 2-piperidone to its endo-isomer.
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