engleski

Tandem β-Elimination/hetero-Michael Addition Rearrangement of the N-Alkylated Pyridinium Oxime to O-Alkylated Pyridine Oxime Ether : An Experimental and Computational Study

A novel OH−-promoted tandem reaction involving C(β)–N+(pyridinium) cleavage and ether C(β)–O(oxime) bond formation in aqueous media has been presented. The study fully elucidates the fascinating reaction behavior of N-benzoylethylpyridinium-4-oxime chloride inaqueous media under mild reaction conditions. The reaction journey begins with the exclusive β- elimination and formation of pyridine-4-oxime and phenyl vinyl ketone and ends with the formation of O-alkylated pyridine oxime ether. A combination of experimental and computational studies enabled the introduction of the new type of rearrangement process that involves a unique tandem reaction sequence. We showed that O-benzoylethylpyridine-4-oxime ether is formed in aqueous solution by a base-induced tandem β-elimination/hetero-Michael addition rearrangement of N-benzoylethylpyridinium-4-oximate, the novel synthetic route to this engaging target class of compounds. The complete mechanistic picture of this rearrangement process was presented and discussed in terms of the E1cb reaction scheme within the rate limiting β-elimination step.

Tandem reactions; Pyridine oxime ether; Reaction mechanisms; Rearrangement

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