ChemInform Abstract: Lewis Acid Catalyzed Addition of Pyrazoles to Alkynes: Selective Synthesis of Double and Single Addition Products.

Abstract

Pyrazole derivatives R 0180Lewis Acid Catalyzed Addition of Pyrazoles to Alkynes: Selective Synthesis of Double and Single Addition Products. -The addition of pyrazole (I) to terminal and internal alkynes is efficiently catalyzed by silver or zinc salts. Double [cf. (III)] and single addition products [cf. (IV)/(V)] are selectively obtained depending on the salt used. The reactions are atom-economical and tolerate a wide range of functional groups. The reaction mechanisms are discussed in detail. -(TSUCHIMOTO*, T.; AOKI, K.; WAGATSUMA, T.; SUZUKI, Y.; Eur. J. Org. Chem. 2008, 23, 4035-4040; Dep. Appl. Chem., Meiji Univ., Kawasaki 214, Japan; Eng.) -Mischke 50-114