Solid-phase synthesis of 5-substituted amino pyrazoles.
An efficient method for the solid-supported synthesis of 5-N-alkylamino and 5-N-arylamino pyrazoles is described. This method is general and mild and utilizes readily accessible resin-immobilized beta-ketoamides 2 as starting materials for the preparation of 1. Resin-immobilized beta-ketoamide, aryl-, or alkylhydazine and Lawesson's reagent are suspended in a mixture of THF/Py and heated at 50-55 degrees C to give a resin-bound 5-aminopyrazole, that is liberated from the solid support by treatment with TFA.
Dodd
Dharmpal S
DS
Early Discovery Chemistry, Bristol-Myers Squibb Pharmaceutical Research Institute, P.O. Box 4000, Princeton, New Jersey 08543-4000, USA. dharmpal.dodd@bms.com
Martinez
Rogelio L
RL
Kamau
Muthoni
M
Ruan
Zheming
Z
Van Kirk
Katy
K
Cooper
Christopher B
CB
Hermsmeier
Mark A
MA
Traeger
Sarah C
SC
Poss
Michael A
MA
D000588:Amines / Q000737:chemistry*; D020650:Combinatorial Chemistry Techniques; D015394:Molecular Structure; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry*
D000588:Amines; D011720:Pyrazoles