# Fujiwara–Moritani reaction

The **Fujiwara–Moritani reaction** is a palladium-catalyzed oxidative coupling in which an aromatic C–H bond reacts directly with the C–H bond of an alkene (vinylic C–H) to form a new C–C bond, giving an alkenylated arene with hydrogen-derived byproducts such as water. It is also called the oxidative [Heck reaction](https://www.edgepedia.org/heck-reaction) or dehydrogenative Heck reaction, because it couples the same partners as the Mizoroki–Heck reaction without requiring a prefunctionalized aryl halide.<sup>[1](https://mdpi-res.com/bookfiles/book/2026/Catalyzed_MizorokiHeck_Reaction_or_CH_activation.pdf?v=1774918967)</sup><sup> • </sup><sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup>  Reported by Ichiro Moritani and [Yuzo Fujiwara](https://www.edgepedia.org/yuzo-fujiwara) at Osaka University in 1967, it is one of the earliest examples of a [C–H activation](https://www.edgepedia.org/c-h-activation) reaction catalyzed by transition metals, and it appeared five years before the publication of the Mizoroki–Heck reaction itself.<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup><sup> • </sup><sup>[3](https://www.electronicsandbooks.com/edt/manual/Magazine/T/Tetrahedron%20Letters%20UK/1967/Issue_12/1119-1122.pdf)</sup><sup> • </sup><sup>[4](https://fileserver-az.core.ac.uk/download/480433029.pdf)</sup>

| Key fact | Detail |
|---|---|
| First report | 1967, Tetrahedron Letters: a styrene–palladium chloride complex reacted with benzene derivatives in acetic acid to give stilbenes, using stoichiometric palladium<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup><sup> • </sup><sup>[3](https://www.electronicsandbooks.com/edt/manual/Magazine/T/Tetrahedron%20Letters%20UK/1967/Issue_12/1119-1122.pdf)</sup>  |
| First yield | trans-Stilbene from benzene and the styrene–PdCl₂ dimer in about 24% yield; mesitylene gave no product, attributed to steric hindrance<sup>[5](https://www.scinovex.com/articles/W1969605542)</sup> |
| Catalytic version | Pd(OAc)₂-catalyzed olefination of simple (hetero)aromatic substrates, with O₂ combined with copper or silver acetate as oxidant, forming water as by-product<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup> |
| Rate-limiting step (early view) | Electrophilic attack of cationic Pd(OAc)⁺ on the arene, supported by a kinetic isotope effect of kᴅ/kʜ = 3 and faster reaction with electron-rich acetanilides<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup> |
| Acid effect | 0.5–1 equivalent of p-toluenesulfonic acid lowers the reaction temperature from 80 to 20 °C by protonating an acetate ligand to generate Pd(OAc)⁺<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup> |
| Main limitations | Poor regioselectivity, multiple olefin substitutions, and the need for excess arene (often solvent quantities)<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup><sup> • </sup><sup>[6](https://pmc.ncbi.nlm.nih.gov/articles/PMC8179420/)</sup>  |
| Recognition | The 1967 paper has accumulated about 556 citations<sup>[5](https://www.scinovex.com/articles/W1969605542)</sup> |

## Discovery and early development

The original communication described a new synthetic route to stilbene derivatives by substitution of aromatic compounds onto the double bond of a styrene–palladium chloride complex. The authors noted that nucleophilic attack on olefin–palladium chloride complexes was well known, but substitution by aromatic compounds had not been found before.<sup>[3](https://www.electronicsandbooks.com/edt/manual/Magazine/T/Tetrahedron%20Letters%20UK/1967/Issue_12/1119-1122.pdf)</sup> Heating the complex in benzene, toluene, or p-xylene with acetic acid gave the corresponding trans-stilbenes in low yields.<sup>[5](https://www.scinovex.com/articles/W1969605542)</sup>

A second early paper replaced the stoichiometric styrene complex with Pd(OAc)₂, using acetic acid or sodium acetate, which avoided formation of a byproduct.<sup>[4](https://fileserver-az.core.ac.uk/download/480433029.pdf)</sup> In 1969, Fujiwara, Moritani, Danno, and Asano showed that the arylation of olefins could be made catalytic with respect to palladium salts by using cupric acetate, and reported mechanistic evidence for the reaction of a σ-vinyl palladium(II) species with benzene or toluene.<sup>[7](https://www.electronicsandbooks.com/edt/manual/Magazine/J/Journal%20of%20the%20American%20Chemical%20Society%20US/1969%20%20%28vol%20091%29/25%20%20%286895-7210%29/7163-7166.pdf)</sup><sup> • </sup><sup>[8](https://www.sciencedirect.com/science/article/pii/S0022328X00805768)</sup>  Catalytic reactions using Pd(OAc)₂ as precursor were subsequently established for the olefination of simple (hetero)aromatic substrates, with oxygen gas used together with copper or silver acetate to close the catalytic cycle.<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup>

In principle the reaction is more attractive than the Heck arylation in atom and step economy, since no aryl halide is needed. In practice, the lack of a reactive center on a simple arene causes poor regioselectivity and multiple substitution of the olefin, and through the end of the 20th century synthetic chemists largely preferred the Heck reaction.<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup>

## Mechanism

The catalytic cycle follows a Heck-type sequence: arene C–H metalation forms an arylpalladium (palladacycle) intermediate, which undergoes migratory insertion of the alkene and β-hydride elimination to release the C–C coupled product and a Pd–H species; reoxidation of Pd(0) or Pd–H back to Pd(II) closes the cycle.<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup><sup> • </sup><sup>[9](https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.201303670)</sup>

**C–H metalation.** Two descriptions of the arene activation step coexist. Work by the de Vries group proposed electrophilic attack of cationic Pd(OAc)⁺ on the arene ring as the turnover-limiting step, based on three observations: the reaction is faster with electron-rich acetanilides (Hammett correlation); a significant kinetic isotope effect of kᴅ/kʜ = 3 is measured with acetanilide-h₅ versus d₅; and the isolated palladacycle reacts with the olefin an order of magnitude faster than the in situ catalyst. A study by Brown and co-workers in the absence of acetate ions also found first-order dependence on the anilide, zero order in benzoquinone, and a modest alkene effect, consistent with rate-limiting metalation.<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup> Computational work by MacGregor and co-workers instead supports an acetate-assisted concerted metalation–deprotonation (CMD) pathway for the C–H metalation step, and carboxylic acid additives have been shown to promote C–H activation both kinetically and thermodynamically.<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup><sup> • </sup><sup>[10](https://electronicsandbooks.com/edt/manual/Magazine/C/Chemical%20Reviews/2011_111/ChemRev_2011_111_03_1167-2486/ChemRev_2011_111_03_1315-1345.pdf)</sup>

**Role of acid.** Brønsted acid additives are common in transition-metal [C–H functionalization](https://www.edgepedia.org/c-h-functionalization), and in the Fujiwara–Moritani reaction 0.5–1 equivalent of p-toluenesulfonic acid has a dramatic effect, allowing the reaction temperature to drop from 80 to 20 °C. The acid is thought to protonate an acetate ligand, generating the catalytically active Pd(OAc)⁺.<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup>

**Revised kinetics.** A 2020 reinvestigation by Christopher J. Mulligan, Jeremy S. Parker, and King Kuok (Mimi) Hii of Imperial College London, with [AstraZeneca](https://www.edgepedia.org/astrazeneca), used reaction calorimetry and spectroscopy on the coupling of p-methylacetanilide with n-butyl acrylate catalyzed by Pd(OAc)₂ with TsOH and benzoquinone. They identified the most active catalyst and found, contrary to the earlier picture, that the catalytic turnover rate is independent of all stoichiometric reagents; catalyst regeneration and deactivation pathways were also discussed.<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup><sup> • </sup><sup>[11](https://www.rsc.org/suppdata/d0/re/d0re00133c/d0re00133c1.pdf)</sup>

## Regioselectivity and directing groups

For simple arenes the reaction often requires excess arene as solvent and gives mixtures of regioisomers. Directing groups address this by holding palladium next to a specific C–H bond: anilides, for example, undergo regioselective ortho-palladation with Pd(OAc)₂ to form palladacycles that react with alkenes to give Heck-type products, a reactivity reported by Horino and Inoue in 1979.<sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup> Kinetic studies on the anilide system showed first-order dependence on anilide and palladium but no dependence on benzoquinone, alkene, or p-TsOH, and the isolated palladacycle was itself an effective catalyst.<sup>[12](https://pubs.rsc.org/en/content/articlelanding/2010/dt/c0dt00378f)</sup>

Directing-group control extends to heterocycles. In 2-pyridones, a stoichiometric amount of Pd(OAc)₂ gave Fujiwara–Moritani-type alkenylation with acrylates selectively at C5 (Itahara, 1984), and a later catalytic variant with Cu(OAc)₂ showed that site selectivity can be decided at the olefin insertion step rather than the palladation step, since C–H palladation occurred reversibly at both C5 and C3.<sup>[13](https://pubs.rsc.org/en/content/articlehtml/2018/sc/c7sc04509c)</sup> For undirected arenes, ligand-enabled systems have become a major strategy: in 2017 Yu described pyridone ligands forming 2:1 complexes with palladium for nondirected [C–H olefination](https://www.edgepedia.org/c-h-olefination), and computational work indicates the C–H activation proceeds through a base-assisted concerted mechanism before reaction with the olefin.<sup>[14](https://pmc.ncbi.nlm.nih.gov/articles/PMC4902085/)</sup> [Electrochemical oxidation](https://www.edgepedia.org/electrochemical-oxidation) offers an alternative to chemical oxidants, with a non-directed Pd-catalyzed electrooxidative olefination of simple arenes reported as a variant of the reaction.<sup>[15](https://pubs.rsc.org/en/content/articlehtml/2022/sc/d2sc03288k)</sup>

## Modern variants and applications

**Asymmetric catalysis.** The enantioselective Fujiwara–Moritani reaction remains a significant challenge. The first intermolecular asymmetric example was reported by Mikami and co-workers in 1999, coupling benzene with cyclic alkenes using a Pd complex derived from a chiral sulfonylamino-oxazoline ligand.<sup>[16](https://pubs.rsc.org/en/content/articlehtml/2012/cy/c2cy20111a)</sup>

**Greener conditions.** Reactions of anilides have been run without external acids, at room temperature, in water as the only medium, using the dicationic salt [Pd(MeCN)₄](BF₄)₂ with benzoquinone and AgNO₃ in a PTS surfactant; this combination gave a 95% yield of the desired cinnamate product.<sup>[17](https://pmc.ncbi.nlm.nih.gov/articles/PMC11216193/)</sup> Heterogeneous variants include a palladium–polyoxometalate nanomaterial used for oxidative olefination of anilides with acrylates and molecular oxygen as terminal oxidant, and a reusable Pd/C system with benzoquinone and TsOH for ortho-functionalization of acetanilides, with palladium leaching of only 4 ppm.<sup>[18](https://pubs.rsc.org/en/content/articlehtml/2016/gc/c6gc00385k)</sup><sup> • </sup><sup>[19](https://link.springer.com/article/10.1007/s41981-020-00077-7)</sup>

**Synthetic applications.** The reaction is used to build quinoline and coumarin frameworks, scaffolds common in pharmaceuticals and agrochemicals; Pd(II)-catalyzed direct C–H alkenylation has been applied to the synthesis and functionalization of highly substituted coumarins.<sup>[20](https://pubs.rsc.org/en/content/articlehtml/2020/cy/d0cy00789g)</sup><sup> • </sup><sup>[21](https://pubs.acs.org/doi/10.1021/acsomega.1c03469)</sup>  Cationic palladium catalysis has also enabled room-temperature Fujiwara–Moritani reactions in a synthesis of the herbicide boscalid.<sup>[22](https://pmc.ncbi.nlm.nih.gov/articles/PMC3152461/)</sup> Acetamides have been used as catalyst-directing groups in couplings of arenes with vinyl sulfones and vinyl sulfonates to make styrenylsulfonyl compounds.<sup>[23](https://onlinelibrary.wiley.com/doi/10.1002/bkcs.70204)</sup>

## Relation to the Heck reaction

The Fujiwara–Moritani reaction shares its core sequence with the Mizoroki–Heck reaction, addition of a Pd–C bond across an alkene followed by β-hydride elimination to give the more substituted alkene, but the arylpalladium precursor is formed by C–H activation rather than oxidative addition of an aryl halide or transmetalation.<sup>[24](https://pubs.rsc.org/en/content/articlehtml/2013/cc/c3cc44842h)</sup><sup> • </sup><sup>[9](https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.201303670)</sup>  This removes the need for a prefunctionalized coupling partner, which is why the reaction is described as atom- and step-economical and environmentally benign, but it transfers the selectivity burden onto the C–H activation step.<sup>[1](https://mdpi-res.com/bookfiles/book/2026/Catalyzed_MizorokiHeck_Reaction_or_CH_activation.pdf?v=1774918967)</sup><sup> • </sup><sup>[2](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)</sup>  Reviews describe the transformation as a central method for forming C(sp²)–C(sp²) bonds in an atom-economical way and a powerful alternative to classical cross-coupling for conjugated organic molecules.<sup>[25](https://www.sciencedirect.com/science/article/abs/pii/S2589597422000806)</sup>

## References

1. [Dehydrogenative Heck-type Reactions: The Fujiwara–Moritani Reaction, RSC Books, From C–H to C–C Bonds](https://mdpi-res.com/bookfiles/book/2026/Catalyzed_MizorokiHeck_Reaction_or_CH_activation.pdf?v=1774918967)
2. [C. J. Mulligan, J. S. Parker, K. K. (Mimi) Hii (2020). Revisiting the mechanism of the Fujiwara–Moritani reaction. React. Chem. Eng., 5, 1104](https://pubs.rsc.org/en/content/articlehtml/2020/re/d0re00133c)
3. [I. Moritani, Y. Fujiwara (1967). Aromatic substitution of styrene–palladium chloride complex. Tetrahedron Letters, 8, 1119–1122](https://www.electronicsandbooks.com/edt/manual/Magazine/T/Tetrahedron%20Letters%20UK/1967/Issue_12/1119-1122.pdf)
4. [A Modular Catalytic Approach (thesis, University of York)](https://fileserver-az.core.ac.uk/download/480433029.pdf)
5. [Aromatic substitution of styrene–palladium chloride complex, Scinovex record](https://www.scinovex.com/articles/W1969605542)
6. [Recent development in transition metal-catalysed C–H olefination (PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC8179420/)
7. [Y. Fujiwara, I. Moritani, S. Danno, R. Asano (1969). J. Am. Chem. Soc., 91, 7166](https://www.electronicsandbooks.com/edt/manual/Magazine/J/Journal%20of%20the%20American%20Chemical%20Society%20US/1969%20%20%28vol%20091%29/25%20%20%286895-7210%29/7163-7166.pdf)
8. [I. Moritani, Y. Fujiwara, S. Danno (1969). Reaction of σ-vinyl palladium(II) with benzene or toluene. J. Organomet. Chem.](https://www.sciencedirect.com/science/article/pii/S0022328X00805768)
9. [Towards Ideal Synthesis: Alkenylation of Aryl C–H Bonds by a Fujiwara–Moritani Reaction, Chem. Eur. J. (Zhou, 2014)](https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.201303670)
10. [Carboxylate-Assisted Transition-Metal-Catalyzed C–H Activation, Chem. Rev. 2011, 111, 1315](https://electronicsandbooks.com/edt/manual/Magazine/C/Chemical%20Reviews/2011_111/ChemRev_2011_111_03_1167-2486/ChemRev_2011_111_03_1315-1345.pdf)
11. [Supplementary Information for Revisiting the mechanism of the Fujiwara–Moritani reaction](https://www.rsc.org/suppdata/d0/re/d0re00133c/d0re00133c1.pdf)
12. [Anilide activation of adjacent C–H bonds in the palladium-catalysed Fujiwara–Moritani reaction, Dalton Trans. 2010](https://pubs.rsc.org/en/content/articlelanding/2010/dt/c0dt00378f)
13. [A lesson for site-selective C–H functionalization on 2-pyridones, Chem. Sci. 2018](https://pubs.rsc.org/en/content/articlehtml/2018/sc/c7sc04509c)
14. [Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC4902085/)
15. [Non-directed Pd-catalysed electrooxidative olefination of arenes, Chem. Sci. 2022](https://pubs.rsc.org/en/content/articlehtml/2022/sc/d2sc03288k)
16. [Asymmetric catalytic carbon–carbon coupling reactions via C–H bond activation, Catal. Sci. Technol. 2012](https://pubs.rsc.org/en/content/articlehtml/2012/cy/c2cy20111a)
17. [Palladium (II)-Catalyzed C–H Activation with Bifunctional Ligands: From Curiosity to Industrialization, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC11216193/)
18. [Heterogeneous catalytic approaches in C–H activation reactions, Green Chem. 2016](https://pubs.rsc.org/en/content/articlehtml/2016/gc/c6gc00385k)
19. [Pushing the boundaries of C–H bond functionalization chemistry using flow technology, J. Flow Chem.](https://link.springer.com/article/10.1007/s41981-020-00077-7)
20. [Palladium-catalysed Heck-type alkenylation reactions in the synthesis of quinolines, Catal. Sci. Technol. 2020](https://pubs.rsc.org/en/content/articlehtml/2020/cy/d0cy00789g)
21. [Pd(II)-Catalyzed Fujiwara–Moritani Reactions for the Synthesis and Functionalization of Substituted Coumarins, ACS Omega 2021](https://pubs.acs.org/doi/10.1021/acsomega.1c03469)
22. [Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature (PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC3152461/)
23. [A brief historical overview of organometallic chemistry in organic synthesis: From the 19th to the 20th century, Bulletin of the Korean Chemical Society (Wiley)](https://onlinelibrary.wiley.com/doi/10.1002/bkcs.70204)
24. [Reactive intermediates in catalytic alkenylation; pathways for Mizoroki–Heck, oxidative Heck and Fujiwara–Moritani reactions, Chem. Commun. 2013](https://pubs.rsc.org/en/content/articlehtml/2013/cc/c3cc44842h)
25. [Palladium-catalyzed oxidative C–H alkenylation: the Fujiwara–Moritani reaction (ScienceDirect)](https://www.sciencedirect.com/science/article/abs/pii/S2589597422000806)

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*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Organic substances › Organic reactions, structure and reference › Organic reactions and synthetic methods › C–C bond formation and coupling methods › Alkylation and coupling reactions › C–H activation and direct functionalization for coupling*

*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Sep 30, 2026; Oct 15, 2026 · Last review: Oct 15, 2026*

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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license