Palladium Porphyrin Catalyzed Hydrogenation of Alkynes: Stereoselective Synthesis of cis-Alkenes

Abstract

(Tetraphenylporphyrin)palladium was developed as a catalyst for the chemoselective and stereoselective hydrogenation of alkynes to cis-alkenes by the syn-addition of hydrogen. Alkynes containing various functional groups were tolerated in the reaction, which gave the corresponding cis-alkenes in good to excellent yields.

Key words

alkynes - alkenes - catalysis - palladium - reductions

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We did not observed the formation of TPP as a result of demetalation of Pd(TPP) in the ¹H NMR spectrum of the crude mixture. Despite this, the formation of Pd colloids as catalytically active species from the Pd(TPP) complex cannot be ruled out. Pd(TPP) might slowly release very small numbers of Pd atoms in situ to form catalytically highly active palladium colloids. For some examples of Pd nanoparticles stabilized by pyridines or their derivatives, see:
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