Register or Submit a manuscript.
Quick Link
Advances in Chemical Research

(ISSN 2692-0344)

Advances in Chemical Research (ACR) is an international peer-reviewed Open Access journal published quarterly online by LIDSEN Publishing Inc. This periodical is devoted to publishing high-quality papers that describe the most significant and cutting-edge research in all areas of chemistry. 

As well as reflecting the traditional core subjects of analytical, inorganic, organic and physical chemistry, the journal also features a broad range of chemical research in areas including, but not limited to, catalysis, computational and theoretical, environmental, green , medicinal, nuclear, polymer, supramolecular and surface chemistry. Other cross-disciplinary topics, such as bioinorganic, bio-organic, organometallic and physical–organic chemistry, will also be featured. 

Main research areas include (but are not limited to):
Organic chemistry
Inorganic chemistry
Physical chemistry
Chemical biology
Analytical chemistry
Supramolecular chemistry
Theoretical chemistry
Computational chemistry
Green chemistry
Structural chemistry
Energy and environmental chemistry

Read more

Archiving: full-text archived in CLOCKSS.

Rapid publication: manuscripts are undertaken in 8 days from acceptance to publication (median values for papers published in this journal in  2020, 1-2 days of FREE language polishing time is also included in this period).

This title discontinued as of 2022, and no longer receiving submissions.

Current Issue: 2022  Archive: 2021 2020 2019
Open Access Short Review

Personal Observations on the Critical and Unusual Role of Palladium Environment on Reaction Pathways

Jacques Muzart *

Institut de Chimie Moléculaire de Reims, UMR 7312, CNRS - Université de Reims Champagne-Ardenne, B.P. 1039, 51687 Reims Cedex 2, France

* Correspondence: Jacques Muzart

Academic Editor: Maxim L. Kuznetsov

Special Issue: Coordination Chemistry and Metal Complexes

Received: October 10, 2019 | Accepted: December 31, 2019 | Published: January 08, 2020

Advances in Chemical Research 2020, Volume 2, Issue 1, doi:10.21926/acr.2001003

Recommended citation: Muzart J. Personal Observations on the Critical and Unusual Role of Palladium Environment on Reaction Pathways. Advances in Chemical Research 2020; 2(1): 003; doi:10.21926/acr.2001003.

© 2020 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.

Abstract

This article summarizes some surprising palladoreactions occurring in a transition metal environment, discovered by our team, and the proposed corresponding mechanisms.

Graphical abstract

Click to view original image

Keywords

Palladium; ethylenic bond; solvent; competing reaction pathways; mechanism; serendipity

1. Introduction

My interest in palladium in organic chemistry came from the reading of the 1977 Trost review [1] during my postdoctoral research in Corey’s laboratory. Back to my Alma matter in late 1978, I was looking for new research subjects. My knowledge in photochemistry, acquired during my doctoral thesis [2], urged me to study the photoreactivity of η3-allylpalladium complexes. Having obtained 1,5-dienes from the UV light-mediated coupling of the allyl fragments in MeCN under the argon atmosphere [3], I undertook the preparation of squalene from E,E-farnesol [4]. This work led to my first observation of the critical role of an unreactive remote ethylenic bond in a palladoreaction. This unexpected observation was an incident of serendipity − that is by accident [5].

These studies were the outcome of forty-year research largely focused on palladium in organic chemistry. The initial topic was chosen, as I, unfortunately, was not aware of older papers from Hojabri who only observed the decomposition of the η3-allylpalladium complex of b-pinene under UV irradiation in EtOH, without dimerization of the allyl ligands or effect of oxygen [6,7]. Actually, we observed, under an oxygen atmosphere, the oxidation of the allyl moieties into conjugated carbonyl compounds [8,9] even in EtOH [10].

The above role of a remote ethylenic bond and other unexpected results due to the Pd environment, which we observed over the years, are the matter of this short review.

2. Remote Ethylenic Bond

2.1 Allylpalladium Isomerization

Using the preparation procedure of bis(m-chloro)bis(η3-allyl)dipalladium complexes [11,12,13], I treated E,E-farnesyl chloride (1) with substoichiometric amounts of Pd2(dba)3.CHCl3 in benzene at room temperature. Surprisingly, a 1:1 mixture of syn- and anti-η3-allylpalladium complexes1 2a and 2b was isolated (Figure 1) [4]. Suspecting the possible role of one of the remote C=C bonds of 1 in the formation of the mixture, geranyl (3), neryl (4), and phytyl (5) chlorides were treated under the same conditions. A 1:1 mixture of 6a and 6b was obtained from 3 and 4, while 7a (7a/7b > 9)2 was selectively produced from 5. RMN studies of the excess of allylic chlorides 3 and 4 recovered at the end of the reactions showed that they were not isomerized under the experimental conditions. Stirring the solution of 7a with a large amount (≈1000 equiv.) of cyclohexene or 2-methylbut-2-ene led only to very poor isomerization at room temperature. Then, a 6:4 mixture of 7a and 7b was isolated from the reaction of 5 with Pd2(dba)3.CHCl3 in the presence of 100 equiv. of 2-methylbut-2-ene.

Click to view original image

Figure 1 Allylic chlorides and corresponding η3-allylpalladium complexes.

According to the above experiments, the formation of the syn and anti mixtures is promoted by the intra- or intermolecular participation of an isolated C=C bond. Isomerization preceding the formation of the dimeric complex is suspected. This could occur via the η3-η1-η3 equilibrium of monomeric allylpalladium intermediates [16] having an ethylenic bond as a ligand (Figure 2).

Click to view original image

Figure 2 The η3-η1-η3 equilibrium.

Subsequently, Åkermark‘s team rediscovered the formation of the isomeric η3-allylpalladium complex mixture from geranyl and neryl chlorides [17,18], while Rovis and Johnson provided an overview of olefins influencing the outcome of various reactions [19].

2.2 Oxidation Inhibition

In 1995, we disclosed the oxidation of alcohols using catalytic amounts of both PdCl2 and Adogen 4643 in 1,2-dichloroethane (DCE) containing sodium carbonate [20]. The insoluble palladium dichloride reacts with ammonium salt to yield the soluble palladium salt [PdCl4]2- [21], which further oxidizes the alcohol. The resulting reduced Pd species gets inserted into a C-Cl bond of DCE. Subsequent elimination of ethylene regenerates the active catalyst [20,22]. Using the procedure for the lactonization of 1,4- and 1,5-diols, we surprisingly obtain the formation of lactol 9uexo from cis-endo-2,3-bis(hydroxymethyl)bicyclo[2.2.1]hept-5-ene (8u) although cis-endo-2,3 bis(hydroxymethyl)bicyclo[2.2.1]heptane (8s) provided lactone 10s (Figure 3) [23,24]. Furthermore, 9uexo was almost unchanged under the same experimental conditions without production of 10u, whereas the latter was effectively produced from 9uexo using pyridinium dichromate in CH2Cl2 (Figure 3) [25,26] or by the Swern oxidation method [27]. Moreover, our Pd procedure led to the effective oxidation of lactol 11 into the corresponding lactone [24].

Click to view original image

Figure 3 Oxidation of 8u, 8s, 9uexo, 11 and 13.

The above results clearly demonstrated that the lack of formation of 10u from 8u under Pd-conditions was attributable to the C=C bond. In order to explain this unusual role, we considered the plausible intermediates of the process (Figure 4; the absence of a juxtaposed u or s letter as suffix to compound numbers of Figure 4 and corresponding text means that these numbers correspond indifferently to either the unsaturated or the saturated substrate.). Hydroxyaldehyde HAd may be in equilibrium with lactols 9exo and 9endo and may react with [PdCl4]2- to give alkoxypalladium aldehyde PAd. The low reactivity of aldehyde 13 under the reaction conditions (Figure 3) is not in favor of the formation of hydroxyacid HAc from Had4. Furthermore, unsaturated HAcu is expected to spontaneously generate lactone 10u [29,30], which, in fact, was not produced from the Pd-catalyzed reaction of 8u. The pallado-intermediates, P9exo and P9endo, may be produced from 9exo and 9endo (path b) or Pad (path a). Subsequent b-H elimination would afford 10, but this only occurs for the formation of 10s.

Click to view original image

Figure 4 Oxidation of 8u and 8s; plausible intermediates.

The analysis of the literature led us to reject some hypotheses5 and to propose that (i) palladation of HAd (path a) is preferred over that of lactols (path b), and (ii) the intramolecular reaction of PAd occurs through the stereoselective approach of the alkoxypalladium moiety to one face of the aldehyde to afford P9endo. When the latter is obtained from 8s, the b-H elimination easily occurs to deliver 10s. In contrast, P9uendo obtained from 8u undergoes a ligand exchange leading to palladacycle PCu (Figure 5). The syn relationship between O-Pd and C-H bonds, which would allow the b-H elimination leading to the carbonyl unit [31,32], is prevented in PCu. That favors alkoxyde exchange with diol 8u to afford 9uendo. The latter evolves towards 9uexo which is a more stable isomer [33,34,35].

Click to view original image

Figure 5 Role of the C=C bond in the formation of lactol 9uexo.

The apparent absence of 9uexo evolution under the aforementioned Pd-catalyzed reaction conditions is a “no reaction” reaction [36,37], which involves HAdu, 9uendo, PCu, alcoholysis and equilibration regenerating the starting substrate.

3. Oxidation Versus Etherification

The above catalytic Pd procedure is efficient for the oxidation of 1-indanol (15) into 1-indanone (16) [20]. We obtained a similar result using the soluble palladium salt synthesized from PdCl2 and n-Bu4NCl instead of the PdCl2/Adogen 464 association (Figure 6, path a) [21,38]. Surprisingly, soluble (RCN)2PdCl2 produced di(1-indanyl) oxide (17) at a high yield, even in the absence of the base (Figure 6, path b) [38].

Click to view original image

Figure 6 Influence of the Pd environment on the reaction pathways of 1-indanol.

We rationalized the formation of 16 and 17 through two competitive pathways catalyzed by L2PdCl2 (L = Cl- or RCN), i.e., with [PdCl4]2- and (RCN)2PdCl2, respectively (Figure 7) [38]. In contrast to the anionic catalyst (L = Cl-), the neutral catalyst (L = RCN) is electrophilic [39,40,41,42]. The exchange of ligand between L2PdCl2 and 15 affords 7A. The evolution of 7A depends on the electrophilicity of L2PdCl2. Transition metals having Lewis acid properties mediate the formation of ethers from alcohols [43,44]. Consequently, 7A formed from the anionic catalyst evolves toward 16 via the ketonization pathway [20,22], while 7A formed from (RCN)2PdCl2 undergoes heterolytic cleavage of the C-OH bond leading to the ionic species 7B. The latter reacts with 15 to give ether 17, water and the starting catalyst.

Click to view original image

Figure 7 Pathways leading to either oxidation or etherification of 1-indanol.

4. Solvent-Mediated Pathways

4.1 Halide Exchange Versus Alkylation

As pointed out in the introduction of the present discourse, the irradiation of a bis(μ-chloro)bis(η3-allyl)dipalladium complex in deoxygenated MeCN leads to the allyl coupling. Thus, the I-carvone complex 18 provided 19 (Figure 8, path a) [3]. Then, we looked for different photoreactions [45]. Having observed the lack of photoreactivity of 18 in CH2Cl2 in the absence of additive, this solvent was firstly chosen for reactions in the presence of organic halides. Halogen-exchanged complexes 20 were thus isolated (Figure 8, path b). Changing CH2Cl2 for DMF6, the reaction with benzyl bromide led to a 1:1 mixture of allylic alkylation and allyl coupling products 21 and 19, respectively (Figure 8, path c). These results showed that the species able to temporarily coordinate to palladium, such as MeCN or DMF, are required to form the C-C bonds under these irradiation conditions. In fact, we obtained the results similar to those in DMF when the photolysis in CH2Cl2 was carried with PPh3 as an additive (Figure 8, path c). The analysis of these reactions by EPR (electron paramagnetic resonance) [51] and CINDP (chemically induced dynamic nuclear polarization) [52] spectroscopies demonstrated their radical character.

Click to view original image

Figure 8 Dependence of the photoreactivity of η3-allylpalladium complex 18 on the environment.

4.2 η1- Versus η3-Allylpalladium

Our synthesis of enantiopure vinylmorpholines by the Pd0-catalyzed diastereoselective disubstitution of (Z)-1,4-diacetoxy-2-butene (22) with chiral amino alcohols in THF [53] urged us to examine the isomerization of the substrate [54]. Golding’s team briefly reported that treatment of 22 with catalytic Pd(PPh3)4 in PhH at room temperature gave (E)-1,4-diacetoxy-2-butene (23) [55]. At 70-72°C in THF, we obtained a mixture of 23 and 1,2-diacetoxy-3-butene (24). The two compounds were also produced in DMF. Monitoring these reactions by 1H NMR resulted in unexpected observations. While 23 and 24 were produced in DMF at a constant 23/24 ratio, the latter varied with time in THF (Figure 9). After 15 min, the amount of 23 decreased to afford the 23/24 equilibrium, indicating that, in THF, 24 was mainly produced from 23 rather than from 22. Subsequent treatments of 23 and 24 with Pd(PPh3)4 in THF showed an equilibrium between them. According to these results, the isomerization of 22 occurs as depicted in Figure 10 [54].

Click to view original image

Figure 9 Isomerization of 22 (dark line) into 23 (red line) and 24 (blue line) using Pd(PPh3)4 (0.05 equiv.) at 70 72°C in DMF or THF.

Click to view original image

Figure 10 Formation of 23 and 24 according to monitoring analysis.

Allypalladium intermediates with the η3-η1-η3 mechanism were proposed for the Z/E-isomerization and the 1,3-transposition of allylic acetates [56]. The proposed reaction pathways of 22 was based on the demonstration given by Amatore and Jutand about the influence of solvent on the species formed from allyl acetate, Pd(dba)2 and PPh3: ‘‘in THF, the acetate ion sticks on the palladium(II) complex (ion pair)’’ while ‘‘in DMF (free ions), the acetate is located far from the cationic η-allylpalladium(II) center’’ [57,58]. The reaction of 22 with the catalyst leads to cationic η3-allylpalladium intermediate 11A that is in equilibrium with the η1-allyl palladium species 11B (Figure 11). The rotation around the AcOC-C(allyl)Pd bond gives 11C that may afford either 23 by nucleophilic addition of the acetate anion to the external terminus of the allyl group, or η3-allylpalladium complex 11D. The latter may also be formed from 23. 11C being a tight ion-pair in THF, the close proximity of the acetate anion with the allyl moiety favors the efficient addition leading to 23. Whereas in DMF, the separation of the two entities favors the formation of 11D. The latter evolves toward 23 and 24.

Click to view original image

Figure 11 Dependence on the solvent of isomerization intermediates.

Pd(PPh3)4-catalyzed isomerization of (Z)-1-(t-butyldimethylsilyloxy)-4-acetoxy-2-butene and (Z)-1-(t-butyldiphenylsilyloxy)-4-acetoxy-2-butene led to similar results [59]. Different intermediates have been proposed for the PdII-catalyzed isomerization of 22, 23 and 24, and the role of the environment of palladium due to THF or DMF on the reactivity has also been highlighted [60].

4.3 Selectivity

While only allyl alcohol 25 and allyl ether 26 were obtained in the presence of acetylacetonate (acacH) from the reaction of 1-acetoxy-1,3-diphenylpropene (27) in MeOH under basic conditions, the addition of H2O provided a 55:40 mixture of 26 and the cross-coupling product 28 (Figure 12, paths a and b, respectively) [61]. Thus, water may promote a Tsuji-Trost-type reaction under metal-free conditions. The selectivity in 28 was strongly increased (Figure 12, path c) [62] by catalytic amounts of both (MeCN)2PdCl2 and the highly hydrophilic ligand LH (Figure 13) that we previously used for Cu-catalyzed allylic acetoxylations in water [63]. Repeating the reaction in the absence of water dramatically decreased the yield of the Tsuji-Trost adduct with the production of the compounds obtained in MeOH under metal-free conditions (Figure 12, path d). Thus, water also promotes the Pd catalyzed addition of acacH to 27.

Click to view original image

Figure 12 Dependence of selectivity on the presence of water.

Click to view original image

Figure 13 A water-soluble ligand.

ESI-MS (electrospray ionization mass spectrometry) analysis of these reactions led us to assume the possibility of in situ formation of palladium acetylacetonate complex 29 and the absence of η3-allylpalladium intermediates (Figure 14) [62]. As a result, it was proposed that 29, which would be a more effective nucleophile than acacK and MeOK, reacts with the water-activated substrate. The efficient recycling of the catalyst [62] showed that a PdII complex is truly immobilized in water, and led to assume the production of water-coordinated palladium species such as 30 as intermediates of the catalytic cycle.

Click to view original image

Figure 14 Formation of a Tsuji-Trost product without η3-allylpalladium intermediate.

5. Conclusion

The above examples highlight the unexpected observations made in the course of our studies, on the effect of the palladium environment on the outcome of reactions. Of course, several critical roles of the palladium environment have also been documented in the literature. These influences on the reactivity have attracted tremendous attention toward palladium in organic chemistry. New reactions and mechanisms are often serendipitously discovered but nevertheless, in most cases, they are the outcomes of deep investigations and reflections rather than good fortune [5].

Acknowledgments

I am grateful to colleagues and students from the Universities of Barcelona, Girona, Grenoble, Lille, Lodz, Marseille, Oldenburg, Prague, Reims and York whose names are cited in the references, for their involvement in the above reactions. I thank CNRS for the freedom in the choice of my research activities.

Author Contribution

Jacques Muzart did the whole writing of the review.

Competing Interests

The author has declared that no competing interests exist.

References

  1. Trost BM. Organopalladium intermediates in organic synthesis. Tetrahedron. 1977; 33: 2615-2649. [CrossRef]
  2. Muzart J. Doctoral thesis: Préparation, réactivité photochimique d'α-époxycétones et de b-dicétones. Paris: Reims University; 1976.
  3. Muzart J, Pete JP. Preparation of 1,5-dienes by photolysis of η3-allylpalladium complexes. J Chem Soc Chem Commun. 1980: 257-258. [CrossRef]
  4. Muzart J, Pete J. Complexes η3-allylpalladium: Isomérisation et photolyse; synthèse du squalène. Bull Soc Chim Fr. 1984: 56-58.
  5. Rulev AY. Serendipity or the art of making discoveries. New J Chem. 2017; 41: 4262-4268. [CrossRef]
  6. Hojabri F. Some reactions of π‐allylic palladium complexes prepared from β‐pinene. J Appl Chem Biotechnol. 1973; 23: 205-207. [CrossRef]
  7. Hojabri F. Polymerisation of bicyclohepta‐(2,5)‐diene with palladium‐π‐complexes. J Appl Chem Biotechnol. 1973; 23: 601-605. [CrossRef]
  8. Muzart J, Pale P, Pete JP. Preparation of conjugated carbonyl compounds by photolysis of η3-allylpalladium complexes. J Chem Soc Chem Commun. 1981: 668-669. [CrossRef]
  9. Muzart J, Pale P, Pete J. Photooxydation régiosélective de complexes η3-allylpalladium: Accès à des composés carbonylés α,β-insaturés fonctionnalisés en γ. Tetrahedron Lett. 1983; 24: 4567-4568. [CrossRef]
  10. Muzart J, Pale P, Pète J, Riahi A. Induction par la lumière de l'oxydation des complexes η3-allylpalladium par l'oxygène moléculaire. Bull Soc Chim Fr. 1988: 731-739.
  11. Ukai T, Kawazura H, Ishii Y, Bonnet J, Ibers JA. Chemistry of dibenzylideneacetone-palladium(0) complexes: I. Novel tris(dibenzylideneacetone)dipalladium(solvent) complexes and their reactions with quinones. J Organomet Chem. 1974; 65: 253-266. [CrossRef]
  12. Ito T, Hasegawa S, Takahashi Y, Ishii Y. Chemistry of dibenzylideneacetone-palladium(0) complexes: II. Preparation and oxidation reactions of novel palladium π-olefinic and π-acetylenic complexes. J Organomet Chem. 1974; 73: 401-409. [CrossRef]
  13. Kurosawa H, Ogoshi S, Kawasaki Y, Murai S, Miyoshi M, Ikeda I. Novel dependency of stereochemistry upon metal, ligand, and solvent in oxidative addition of allylic chloride to palladium(0) and platinum(0) complexes. J Am Chem Soc. 1990; 112: 2813-2814. [CrossRef]
  14. Lukas J, Ramakers-Blom J, Hewitt T, De Boer J. Syn-and anti-(1-alkyl-π-allyl)palladium chlorides. J Organomet Chem. 1972; 46: 167-177. [CrossRef]
  15. Frost CG, Howarth J, Williams JM. Selectivity in palladium catalysed allylic substitution. Tetrahedron Asymmetry. 1992; 3: 1089-1122. [CrossRef]
  16. Breutel C, Pregosin PS, Salzmann R, Togni A. An unusual, selective η3-η1 allyl isomerization in a chiral allylic alkylation catalyst. J Am Chem Soc. 1994; 116: 4067-4068. [CrossRef]
  17. Åkermark B, Hansson S, Krakenberger B, Vitagliano A, Zetterberg K. Alkylation of (π-allyl)palladium systems. Mechanism and regiocontrol. Organometallics. 1984; 3: 679-682. [CrossRef]
  18. Åkermark B, Vitagliano A. Reactivity and syn-anti isomerization of (η3-geranyl)-and (η3-neryl)palladium complexes. Evidence for electronic control of the regiochemistry of nucleophilic addition. Organometallics. 1985; 4: 1275-1283. [CrossRef]
  19. Johnson JB, Rovis T. More than bystanders: The effect of olefins on transition-metal-catalyzed cross-coupling reactions. Angew Chem Int Ed Engl. 2008; 47: 840-871. [CrossRef]
  20. Aït-Mohand S, Hénin F, Muzart J. Palladium(II)-mediated oxidation of alcohols using 1,2-dichloroethane as Pd(0) reoxidant. Tetrahedron Lett. 1995; 36: 2473-2476. [CrossRef]
  21. Bouquillon S, du Moulinet d’Hardemare A, Averbuch-Pouchot MT, Hénin F, Muzart J. Synthesis and characterization of monomeric and dimeric palladium(II)–ammonium complexes: Their use for the catalytic oxidation of alcohols. Polyhedron. 1999; 18: 3511-3516. [CrossRef]
  22. Rothenberg G, Humbel S, Muzart J. Palladium-catalysed oxidation of alcohols to carbonyl compounds with 1,2-dichloroethane as the primary oxidant: A theoretical study. J Chem Soc Perkin Trans 2. 2001: 1998-2004.
  23. Aı̈t-Mohand S, Muzart J. Palladium-catalyzed oxidative cyclization of 1,4-and 1,5-diols in 1,2-dichloroethane. J Mol Catal A: Chem. 1998; 129: 135-139. [CrossRef]
  24. Aït-Mohand S, Hénin F, Muzart J. Palladium-catalyzed oxidations: Inhibition of a Pd−H elimination by coordination of a remote carbon−carbon double bond. Organometallics. 2001; 20: 1683-1686. [CrossRef]
  25. Aït-Mohand S. Doctoral thesis: Catalyse de réactions d'oxydation : Utilisation du percarbonate de sodium et régénération d'espèces palladiées actives par le 1,2-dichloroéthane: Reims University; 1997.
  26. Taniguchi T, Ogasawara K. Specific asymmetric mono-epoxidation of Meso 2,3-syn-bis-allylic alcohols having a bicyclo [2.2.1] heptane framework. Tetrahedron Lett. 1997; 38: 433-436. [CrossRef]
  27. Taniguchi T, Goto Y, Ogasawara K. Preparation of a promising cyclobutanone chiral building block: Its stereochemistry and utilization. Synlett. 1997: 707-709. [CrossRef]
  28. Aït-Mohand S, Levina A, Muzart J. Pyridinium dichromate-catalyzed oxidative cleavage of α-functionalized benzylic alcohols by sodium percarbonate under phase-transfer conditions. Synth Commun. 1995; 25: 2051-2059. [CrossRef]
  29. Jaeschke G, Seebach D. Highly enantioselective ring opening of cyclic meso-anhydrides to isopropyl hemiesters with Ti−TADDOLates: An alternative to hydrolytic enzymes?. J Org Chem. 1998; 63: 1190-1197. [CrossRef]
  30. March J. Advanced organic chemistry. 4th Ed. New York: John Wiley; 1992. p. 393
  31. Chung K, Banik SM, De Crisci AG, Pearson DM, Blake TR, Olsson JV, et al. Chemoselective Pd-catalyzed oxidation of polyols: Synthetic scope and mechanistic studies. J Am Chem Soc. 2013; 135: 7593-7602. [CrossRef]
  32. Li Y, Lin Z. Understanding the reaction mechanisms of Pd-catalysed oxidation of alcohols and domino oxidation–arylation reactions using phenyl chloride as an oxidant. Org Chem Front. 2014; 1: 1188-1196. [CrossRef]
  33. Corey E, Palani A. A method for the selective oxidation of 1,4-diols to lactols. Tetrahedron Lett. 1995; 36: 3485-3488. [CrossRef]
  34. Corey E, Palani A. A mechanistic model for the selective oxidation of 1,4-diols to γ-lactols by o-iodoxybenzoic acid. Tetrahedron Lett. 1995; 36: 7945-7948. [CrossRef]
  35. Lieb F, Niewöhner U, Wendisch D. 6‐(3‐Carbamoylbicyclo [2.2.1] hept‐2‐yl) hexansäuren, eine neue klasse von TxA2‐antagonisten. Liebigs Ann Chem. 1987: 607-615. [CrossRef]
  36. Berson JA, Willcott MR. Bredt rule interdictions of cyclopropane rearrangements. The vinylnortricyclenes. J Org Chem. 1965; 30: 3569-3572. [CrossRef]
  37. Baldwin JE, Dunmire DA. The “no reaction” reaction of 1-vinylnortricyclene to tricyclo [4.2.1.03,7] non-3-ene. J Org Chem. 2000; 65: 6791-6794. [CrossRef]
  38. Bouquillon S, Hénin F, Muzart J. Critical role of the coordination environment of palladium dichloride on the course of its reaction with secondary benzylic alcohols: Selective oxidation or etherification catalysts. Organometallics. 2000; 19: 1434-1437. [CrossRef]
  39. Sen A, Lai TW. Catalysis by solvated transition-metal cations. Novel catalytic transformations of alkenes by tetrakis(acetonitrile)palladium ditetrafluoroborate. Evidence for the formation of incipient carbonium ions as intermediates. J Am Chem Soc. 1981; 103: 4627-4629. [CrossRef]
  40. Sen A, Lai TW. Oligomerization and isomerization of olefins by η3-allyl complexes of palladium. The role of the allyl group. Organometallics. 1983; 2: 1059-1060. [CrossRef]
  41. Lipshutz BH, Pollart D, Monforte J, Kotsuki H. Pd(II)-catalyzed acetal/ketal hydrolysis/exchange reactions. Tetrahedron Lett. 1985; 26: 705-708. [CrossRef]
  42. Tenaglia A, Kammerer F. Palladium(II)-catalyzed dehydrative cyclization of cis-4-Alkylcycloalken-2-ols. Synthesis of tricyclic spiroketals in a one-pot sequence. Synlett. 1996: 576-578. [CrossRef]
  43. Aït‐Mohand S, Muzart J, Lunak S. Chlorides and acetylacetonates of transition metals as catalysts for the oxidation of 1-indanol by sodium percarbonate. Chem Ber. 1997; 130: 1655-1658. [CrossRef]
  44. Salehi P, Iranpoor N, Behbahani FK. Selective and efficient alcoholyses of allylic, secondary-and tertiary benzylic alcohols in the presence of iron(III). Tetrahedron. 1998; 54: 943-948. [CrossRef]
  45. De Poorter B, Muzart J, Pete JP. Photoreactivity of (η3-allyl)palladium complexes in the presence of organic halides. Organometallics. 1983; 2: 1494-1497. [CrossRef]
  46. Muzart J. N,N-dimethylformamide: Much more than a solvent. Tetrahedron. 2009; 65: 8313-8323. [CrossRef]
  47. Ding S, Jiao N. N,N‐dimethylformamide: A multipurpose building block. Angew Chem Int Ed Engl. 2012; 51: 9226-9237. [CrossRef]
  48. Batra A, Singh P, Singh KN. Cross dehydrogenative coupling (CDC) reactions of N,N‐disubstituted formamides, benzaldehydes and cycloalkanes. European J Org Chem. 2016: 4927-4947. [CrossRef]
  49. Le Bras J, Muzart J. Recent uses of N,N-dimethylformamide and N,N-dimethylacetamide as reagents. Molecules. 2018; 23: E1939.
  50. Le Bras J, Muzart J. N,N‐dimethylformamide and N,N‐dimethylacetamide as carbon, hydrogen, nitrogen, and/or oxygen sources. Solvents as reagents in organic synthesis: Reactions and applications. Weinheim: Wiley-VCH; 2017. p. 199-314. [CrossRef]
  51. Crozet MP, Muzart J, Pale P, Tordo P. Photolyse de complexes η3-allylpalladium: Etude par résonance paramagnétique électronique des nitroxydes allyliques formés en présence de nitrosodurène. J Organomet Chem. 1983; 244: 191-200. [CrossRef]
  52. Vermeersch G, Marko J, Muzart J. Photoreactivity of η3-allylpalladium complexes studied by CIDNP. J Chem Soc Perkin Trans 2. 1986: 383-389. [CrossRef]
  53. Thorey C, Wilken J, Hénin F, Martens J, Mehler T, Muzart J. Diastereoselective synthesis of vinylmorpholines by palladium-catalyzed tandem allylic substitutions using enantiopure aminoalcohols as bifunctional nucleophiles. Tetrahedron Lett. 1995; 36: 5527-5530. [CrossRef]
  54. Bouquillon S, Muzart J. Palladium(0)‐catalyzed isomerization of (Z)‐1,4‐diacetoxy‐2‐butene: Dependence of η1- or η3-allylpalladium as a key intermediate on the solvent polarity. European J Org Chem. 2001: 3301-3305. [CrossRef]
  55. Crilley MM, Golding BT, Pierpoint C. Palladium(II)-catalysed rearrangements of allylic acetates in the syntheses of methyl (10E,12Z)-9-hydroxyoctadeca-10,12-dienoate (α-dimorphecolate) and (2E,4Z)-deca-2,4-dienal. J Chem Soc Perkin Trans 1. 1988: 2061-2067. [CrossRef]
  56. Trost BM, Van Vranken DL. Asymmetric transition metal-catalyzed allylic alkylations. Chem Rev. 1996; 96: 395-422. [CrossRef]
  57. Amatore C, Jutand A, Meyer G, Mottier L. Evidence of the reversible formation of cationic π‐allylpalladium(II) complexes in the oxidative addition of allylic acetates to palladium(0) complexes. Chemistry. 1999; 5: 466-473. [CrossRef]
  58. Jutand A. The use of conductivity measurements for the characterization of cationic palladium(II) complexes and for the determination of kinetic and thermodynamic data in palladium-catalyzed reactions. Eur J Inorg Chem. 2003:2017-2040. [CrossRef]
  59. Zawisza AM, Muzart J. Palladium(0)-catalyzed isomerization of (Z)-1-functionalized-4-acetoxy-2-butenes: Solvent and substituent effects. J Organomet Chem. 2010; 695: 62-66. [CrossRef]
  60. Zawisza AM, Bouquillon S, Muzart J. Palladium(II)‐catalyzed isomerization of (Z)‐1,4‐diacetoxy‐2‐butene: Solvent effects. European J Org Chem. 2007: 3901-3904. [CrossRef]
  61. Chevrin C, Le Bras J, Hénin F, Muzart J. Water-mediated transition-metal-free tsuji–trost-type reaction. Tetrahedron Lett. 2003; 44: 8099-8102. [CrossRef]
  62. Chevrin C, Le Bras J, Hénin F, Muzart J, Pla-Quintana A, Roglans A, et al. Allylic substitution mediated by water and palladium: Unusual role of a palladium(II) catalyst and ESI-MS analysis. Organometallics. 2004; 23: 4796-4799. [CrossRef]
  63. Le Bras J, Muzart J. Water-soluble and reusable copper catalyst for the allylic benzoyloxylation of olefins. Tetrahedron Lett. 2002; 43: 431-433. [CrossRef]
Newsletter
Download PDF Download Citation
 87  372
Newsletter