reaction scheme

It seems that the combination of sodium methoxide (a base) and chloroform will generate dichlorocarbene, $\ce{CCl2}$, by α-elimination.

What happens after that, though? It is an ortho formylation like in the Reimer–Tiemann reaction? Or does the nucleophilic oxygen simply attack the carbene?


Dichlorocarbene has been shown to deoxygenate pyridine N-oxide producing phosgene as an initial byproduct. In this case, since methoxide is present, dimethyl carbonate is ultimately formed.[1]

The proposed mechanism involves nucleophilic attack on the carbene by the oxygen, followed by an elimination:


(1) Schweizer, E. E.; O'Neill, G. J. A Novel Deoxygenation Method for Pyridine N-Oxide. J. Org. Chem. 1963, 28 (9), 2460–2461. DOI: 10.1021/jo01044a516.

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