2-Trifluoroacetyl aminoindoles as useful intermediates for the preparation of 2-acylamino indoles

Tetrahedron Letters

Volumn 52, Issue 12, 2011, Pages 1292-1295

  Mangette, John E ^a   Chen, Xuemei ^a   Krishnamoorthy, Ravi ^a   Samuel Vellekoop, A ^a   Csakai, Adam J ^a   Camara, Fatoumata ^a   Paquette, William D ^a   Wang, Hong Jun ^a   Takahashi, Hidenori ^b   Fleck, Roman ^b   Roth, Gregory P ^b,c  

^a ALBANY MOLECULAR RESEARCH INC   (United States)

^b BOEHRINGER INGELHEIM PHARMACEUTICALS INC   (United States)

^c BURNHAM INSTITUTE   (United States)

Author keywords

2 Aminoindole; 2 Aminoindole acylation; Acylaminoindole; Chloroindolenine

Indexed keywords

2 ACYLAMINO INDOLE DERIVATIVE; 2 TRIFLUOROACETYL AMINOINDOLE DERIVATIVE; INDOLE DERIVATIVE; UNCLASSIFIED DRUG;

ACYLATION; ARTICLE; CHEMICAL STRUCTURE; CHLORINATION; DEPROTECTION REACTION;

EID: 79951759187     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2011.01.051     Document Type: Article

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36. Optimization of the direct reaction of amides as shown in Scheme 4 was unfruitful since deprotonation of amides of varying N - H acidity, and difficulties with solubility and nucleophilicity of the resulting salts, necessitated continual reoptimization; the use of sodium (2,2,2-trifluoroacetyl) amide, which was readily formed with sodium hydride, had good solubility in THF and proved to be a good nucleophile in the presence of 15-crown-5 ether, eliminated these difficulties and allowed for diversification in the final step with more routine acylation chemistry.
37. 15-Crown-5 ether, a selective sequestration agent of the sodium cation, was used to increase the nucleophilicity of the trifluoroacetyl amide anion. This gave drastically improved yields of 2. As an example, the yield of 2a without 15-crown-5 was 14%.