1,3-Diketones from Acid Chlorides and Ketones: A Rapid and General One-Pot Synthesis of Pyrazoles
Stephen T. Heller* and Swaminathan R. Natarajan
*Department of Medicinal Chemistry, Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065, Email: stephen_hellermerck.com
S. T. Heller, S. R. Natarajan, Org. Lett., 2006, 8, 2675-2678.
DOI: 10.1021/ol060570p (free Supporting Information)
see article for more reactions
1,3-Diketones, which were synthesized in situ from ketones and acid chlorides, were converted into pyrazoles by the addition of hydrazine. This method allows a fast and general synthesis of previously inaccessible pyrazoles and synthetically demanding pyrazole-containing fused rings.
see article for more examples
The reaction works just as well with 1 eq of hydrazine (just more slowly in the condensation phase)
Stephen T. Heller, August 8, 2007