Synthesis 2022; 54(24): 5520-5528
DOI: 10.1055/a-1918-4406
paper

N-Heterocyclic Carbene Catalyzed Cross Dehydrogenative Coupling of Aldehydes with Methanol: Combined Use of Eosin Y and Hexachloroethane

Eito Yoshioka
,
Hiroki Takahashi
,
Akane Kubo
,
Miki Ohno
,
Fuuka Watanabe
,
Rino Shiono
,
Yuuki Miyazaki
,
Hideto Miyabe
This work was supported by a Japan Society for the Promotion of Science­ (JSPS) KAKENHI Grant-in-Aid for Scientific Research (C) (Grant Number 20K06954, to H.M.).


Abstract

Cross dehydrogenative coupling of aldehydes with methanol was investigated under organocatalytic conditions based on the cooperation­ between N-heterocyclic carbene and eosin Y·Na as an organophotocatalys­t. The combined use of eosin Y·Na and hexachloro­ethane (C2Cl6) was the effective method for the oxidative esterification of various aldehydes, because the oxidation steps are promoted by two pathways associated with the activated photocatalyst and C2Cl6. In contrast, the combined use of eosin Y·Na and bromotrichloromethane (BrCCl3) was effective only for the oxidative esterification of simple cinnamaldehyde derivatives, in which BrCCl3 promotes the oxidation as a brominating reagent toward radical intermediates.

Supporting Information



Publication History

Received: 01 July 2022

Accepted: 04 August 2022

Accepted Manuscript online:
04 August 2022

Article published online:
14 September 2022

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