Lops C, Pengo P, Pasquato L. Highly Efficient Darzens Reactions Mediated by Phosphazene Bases under Mild Conditions.
ChemistryOpen 2022;
11:e202200179. [PMID:
36207800 PMCID:
PMC9547082 DOI:
10.1002/open.202200179]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 08/30/2022] [Indexed: 11/18/2022] Open
Abstract
The highly basic and poorly nucleophilic phosphazene base P1 -t-Bu promotes the Darzens condensation of α-halo esters with aromatic aldehydes affording α,β-epoxy esters in nearly quantitative yields under mild conditions and in short reaction times. The more basic P4 -t-Bu phosphazene was found useful with low reactivity aldehydes. These reactions can be performed in aprotic organic solvents of low polarity, thus minimizing the hydrolysis of α,β-epoxy esters which often accompanies the base-promoted Darzens condensations.
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