20737-58-0Relevant academic research and scientific papers
A simple, modular method for the synthesis of 3,4,5-trisubstituted pyrazoles
McLaughlin, Mark,Marcantonio, Karen,Chen, G-Yi,Davies, Ian W.
, p. 4309 - 4312 (2008/09/21)
(Chemical Equation Presented) A modular approach for the regiocontrolled preparation of pyrazoles bearing substituents on all three carbon atoms is described. Central to this method is the use of a switchable metal-directing group (MDG) to enable sequential direct lithiation of the 3- and 5-positions of the pyrazole ring. Pyrazole boronic esters obtained from these lithiated intermediates can undergo efficient Suzuki cross-coupling under the developed nonaqueous conditions, which minimize undesirable protolytic deboronation. Halogenation of the 4-position provides the means for substitution at the remaining carbon atom.
