Carboxylate Anions Accelerate Pyrrolidinopyridine (PPy)-Catalyzed Acylation: Catalytic Site-Selective Acylation of a Carbohydrate by in Situ Counteranion Exchange

Acylpyridinium ions have been known as catalytically active species in acylation reactions catalyzed by 4-dimethyl­amino­pyridine and its analogues. Acylpyridinium carboxylates were found to be 800–1300 times more reactive than the corresponding acylpyridinium chlorides. A catalytic cycle was develo...

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Bibliographic Details
Published in:Organic letters 2017-06, Vol.19 (12), p.3099-3102
Main Authors: Yanagi, Masanori, Imayoshi, Ayumi, Ueda, Yoshihiro, Furuta, Takumi, Kawabata, Takeo
Format: Article
Language:English
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Summary:Acylpyridinium ions have been known as catalytically active species in acylation reactions catalyzed by 4-dimethyl­amino­pyridine and its analogues. Acylpyridinium carboxylates were found to be 800–1300 times more reactive than the corresponding acylpyridinium chlorides. A catalytic cycle was developed, in which acylpyridinium carboxylates were generated by in situ counteranion exchange from the acylpyridinium chlorides. A catalyst loading as low as 0.01 mol % and catalyst turnover number of up to 6700 were achieved for site-selective acylation of a carbohydrate.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.7b01213