Sonogashira–Hagihara reaction
| Sonogashira coupling | |
|---|---|
| Named after | Kenkichi Sonogashira |
| Reaction type | Coupling reaction |
| Identifiers | |
| Organic Chemistry Portal | sonogashira-coupling |
| RSC ontology ID | RXNO:0000137 |
The Sonogashira reaction is a cross-coupling reaction used in organic synthesis to form carbon–carbon bonds. It employs a palladium catalyst to form a carbon–carbon bond between a terminal alkyne and an aryl or vinyl halide.
The Sonogashira cross-coupling reaction has been employed in a wide variety of areas, due to its usefulness in the formation of carbon–carbon bonds. The reaction can be carried out under mild conditions, such as at room temperature, in aqueous media, and with a mild base, which has allowed for the use of the Sonogashira cross-coupling reaction in the synthesis of complex molecules. Its applications include pharmaceuticals, natural products, organic materials, and nanomaterials. Specific examples include its use in the synthesis of tazarotene, which is a treatment for psoriasis and acne, and in the preparation of SIB-1508Y, also known as Altinicline, a nicotinic receptor agonist.
The Sonogashira cross-coupling reaction was first reported by Kenkichi Sonogashira, Yasuo Tohda, and Nobue Hagihara in their 1975 publication. It is an extension to the Cassar and Dieck and Heck reactions, which afford the same reaction products, but use harsh reaction conditions, such as high temperature, to do so. Both of these reactions make use of a palladium catalyst to carry out the coupling, while Sonogashira uses both palladium and copper catalysts simultaneously. This results in the increased reactivity of the reagents and the ability of the reaction to be carried out at room temperature, making the Sonogashira cross-coupling reaction a highly useful reaction, particularly in the alkynylation of aryl and alkenyl halides. The reaction's remarkable utility can be evidenced by the amount of research still being done on understanding and optimizing its synthetic capabilities. A search for the term "Sonogashira" in Scifinder provides over 1500 references for journal publications between 2007 and 2010. It has become so well known that often, all reactions that use a palladium(0) catalyst to couple a sp2 and even sp3 halide or triflate with a terminal alkyne, regardless of whether or not a copper co-catalyst is used, are termed "Sonogashira reactions," despite the fact that these reactions are not carried out under true Sonogashira reaction conditions.
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