Pd-free, Sonogashira cross-coupling reaction. An update

What is it about?

Highlights • Pd-Free, Sonogashira cross-coupling reaction was highlighted in this review. • Due to the relatively high price of Pd and its toxicity, the Pd-free catalyzed Sonogashira reaction has attracted much attention. • The resultant products from the Sonogashira coupling are important in the synthesis of biologically active molecules, natural products, conjugated polymers, dendrimers, and heterocycles as well as in material science. • The tendency to the use of other transition metals such as Cu, Co, Ag, and Rh, are more environmentally friendly and cheaper than the Pd.

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Why is it important?

Abstract The Sonogashira reaction is a cross-coupling reaction used in organic synthesis to form carbon-carbon bonds. In its classical form, it uses a Pd catalyst as well as copper co-catalyst and amines as the solvents or co-solvents to form a carbon-carbon bond between a terminal alkyne and an aryl or vinyl halide. Due to the relatively high price of Pd and its toxicity, the Pd-free catalyzed Sonogashira cross-coupling reaction has attracted much attention from synthetic organic chemists, both in academia and industry. Several successful attempts have been made, which were introduced in a review article published in 2016. Due to a plethora of relevant papers that appeared in the chemical literature, in this review, we try to underline the recent advances achieved in the Pd-free Sonogashira reaction from 2016 to date.

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