Synthesis and Structure of Novel 1-Aryl-4,4,4-trichloro-1,3-butanediones

• Published in: Synthetic communications Vol. 42; no. 5; pp. 727 - 737
• Main Authors: Flores, Alex F. C., Martins, Mauro J., Frigo, Leandro M., Machado, Pablo, Campos, Patrick T., Malavolta, Juliana L.
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis Group 01-03-2012; Taylor & Francis Ltd
• Subjects: Acetal acylation; diketones; keto-enol equilibrium; trichloromethyl
• ISSN: 0039-7911; 1532-2432
• DOI: 10.1080/00397911.2010.530376

Novel 1-aryl-4,4,4-trichloro-1,3-butanediones in good yields (80-97%) were synthesized in one pot through acetal acylation with trichloroacetyl chloride followed by acid hydrolysis. Structures of all compounds were elucidated by elemental analysis, mass spectrometry, and
1
H/
13
C nuclear magnetic resonance (NMR) measurements. The
1
H/
13
C NMR data showed that trichloromethyl-
β
-diketones 2a-k in solution are predominantly ketoenol. However, the spectroscopic data from 4,4,4-trichloro-2-methyl-1-phenyl-1,3-butabedione (2l) with methyl substituent between carbonyls showed a bias toward the diketo form in solution. X-ray diffraction of monocrystals from 2g and 2i showed that these compounds are cis-ketoenol tautomers.
Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communcations® to view the free supplemental file.