O‑Ylide and π‑Complex Formation in Reactions of a Carbene with Dibenzo and Monobenzo Crown Ethers
journal contributionposted on 14.08.2014 by Pablo A. Hoijemberg, Robert A. Moss, David V. Feinblum, Karsten Krogh-Jespersen
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Reactions of p-nitrophenylchlorocarbene (PNPCC) with various dibenzo crown ethers produce O-ylides and π-complexes; the reactions can be followed via the spectral signatures of the carbene and the products. The O-ylides form most rapidly, but over time they decay in favor of the more stable π-complexes. Extensive computational studies support and refine appropriate structural and mechanistic conjectures. Reactions of PNPCC with monobenzo crown ethers afford only the spectral signatures of O-ylides; monobenzo π-complexes are either not formed in significant concentrations or are spectroscopically silent.