A new Brønsted acid derived from squaric acid and its application to Mukaiyama aldol and Michael reactions

Tetrahedron Letters

Volumn 50, Issue 26, 2009, Pages 3555-3558

  Cheon, Cheol Hong ^a   Yamamoto, Hisashi ^a  

^a UNIVERSITY OF CHICAGO   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

BIS N TRIFLUOROMETHANESULFONYL SQUARAMIDE; BRONSTED ACID; ETHER DERIVATIVE; KETONE; LEWIS ACID; SQUARIC ACID; UNCLASSIFIED DRUG;

ARTICLE; CATALYSIS; CATALYST; CHEMICAL STRUCTURE; DESILYLATION; ELECTRON; MUKAIYAMA MICHAEL REACTION; MUKAIYAMA REACTION; SILYLATION;

EID: 65549170745     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2009.03.060     Document Type: Article

References (23)

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20. 4, filtered, and concentrated. Column chromatography on silica (15% ethyl acetate in hexanes solution) gave 5a as a white solid. (43.4 mg; 96% yield).
21. In all cases of ketones, the undesired by-product 5i was obtained, which was formed between 4i, in situ generated from 3a via hydrolysis, and 3a.{A figure is presented}
22. After careful analysis, these compounds were found to be 5la and 5ll, respectively. Presumably, aldol product 5l was initially formed, but was not stable in this reaction condition. Dehydration presumably took place to produce α,β-unsaturated carbonyl compound 6l. Finally, Michael reaction took place between 6l and silyl enol ether gave either 5la or 5ll.{A figure is presented}
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