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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?

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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:

Mechanism

(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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