Triflic Acid-Mediated Condensation of Phthalimide with Diaryl Ethers as a Route to Spiro-Isoindolinones: Mechanistic Insights and Related Reactions

Phthalimide and N-phenylphthalimide smoothly condense with di-p-tolyl ether in triflic acid (CF3SO3H, TfOH) to obtain the corresponding spiro­[isoindoline-1,9′-xanthen]-3-ones. Structural analogs of phthalimide, such as phthalic anhydride and 1,3-indandione (but not saccharin), show similar reactivi...

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Bibliographic Details
Published in:Journal of organic chemistry 2024-11, Vol.89 (21), p.15931-15940
Main Authors: Genaev, Alexander M., Salnikov, George E., Koltunov, Konstantin Yu
Format: Article
Language:English
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Summary:Phthalimide and N-phenylphthalimide smoothly condense with di-p-tolyl ether in triflic acid (CF3SO3H, TfOH) to obtain the corresponding spiro­[isoindoline-1,9′-xanthen]-3-ones. Structural analogs of phthalimide, such as phthalic anhydride and 1,3-indandione (but not saccharin), show similar reactivity. In contrast, N-(tetrafluoropyridin-4-yl)­phthalimide reacts with DTE by an alternative pathway, yielding isobenzofuran dispiro derivative. The mechanistic aspects of these reactions are discussed on the basis of in situ NMR and theoretical (DFT) studies, providing insights on the key intermediacy of O,O-diprotonated forms of the starting compounds.
ISSN:0022-3263
1520-6904
1520-6904
DOI:10.1021/acs.joc.4c02139