Elsevier

Journal of Catalysis

Volume 417, January 2023, Pages 52-59
Journal of Catalysis

Three-component chemo-selective oxy-allylation of α-diazo carbonyl compounds: Access to α-ternary carboxylic esters

https://doi.org/10.1016/j.jcat.2022.11.025Get rights and content

Highlights

  • Three-component chemo-selective oxy-allylation of α-diazo esters, alcohols (or water), and allylic benzoates was described.

  • Trapping of active protic oxonium ylides with catalytic π-allyl palladium intermediates was proposed for alcohols.

  • Water was also suitable partner in this reaction involving a different allylic migratory insertion of palladium-carbenes.

  • Various α-ternary allylated carboxylic esters were synthesized, involving the formation of two new Csingle bondO and Csingle bondC bonds at the same carbon atom.

Abstract

A synergistic Rh(II)/Pd(0) dual-catalyzed strategy that enabled three-component oxy-allylation of α-diazo esters, alcohols, and allylic benzoates was described. Trapping of active protic oxonium ylides with catalytic π-allyl Pd(II) intermediates was proposed for this reaction. More strikingly, water was also a suitable partner in this reaction involving a different allylic migratory insertion of palladium-carbenes. These transformations provided straightforward access to various α-ternary allylated carboxylic esters using simple and readily available starting materials under redox-neutral conditions, in which two new Csingle bondO and Csingle bondC bonds were generated successively at the carbene center.

Introduction

Transition-metal-catalyzed allylic alkylations of α-diazo carbonyl compounds have been established as indispensable tools for accessing valuable molecules [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24]. A commonly exploited pathway to generate metal-carbenes A from α-diazo esters with allylic reagents, followed by allyl migratory insertion, gives rise to the alkyl-metal intermediate B [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]. In most cases, substituted dienes can be easily obtained by β-hydride elimination of B (Scheme 1a, path I) [2], [3], [4], [5], [6], [7], [8], [9]. For example, Wang and co-workers pioneered the Pd(0)-catalyzed olefination of α-diazo carbonyl compounds with allylic halides, which afforded the poly-substituted 1,3-dienes [2]. However, the intermediate B has been found reluctant to react with external nucleophiles via substitution to deliver α-ternary allylated esters (Scheme 1a, path II) [10], [11], [12]. Therefore, the development of novel and efficient catalytic strategies is of great significance and in high demand.

Multicomponent reactions, involving electrophilic trapping of onium ylides, can offer substantial advantages over traditional approaches to rapidly assemble complex molecules in an atom-economical and convergent manner under mild conditions [24], [25], [26], [27], [28], [29], [30], [31], [32], [33]. Remarkably, Hu [25], [26], [28], [29], [30], [31] and other research groups [32], [33] demonstrated a series of elegant studies about cooperative Rh(II)/Lewis acid (or phosphoric acid) dual-catalyzed nucleophilic additions of protic oxonium ylides C, generated in situ from Rh(II)-catalyzed reactions of α-diazo esters and alcohols, with electron-deficient double bonds (e.g., Cdouble bondO, Cdouble bondN, and Cdouble bondC), instead of [1], [2]-proton transfer [34]. In contrast, the Pd(0)-catalyzed allylic alkylation of protic oxonium ylides C is less explored, probably due to the redox non-compatibility of Rh(II) and Pd(0) catalysts and catalytic deactivations.

Dual transition-metal catalysis has emerged as a powerful strategy for the development of reactivity and selectivity [35], [36], [37], [38], [39]. As a continuation of our efforts in Rh(II)/Pd(0) dual catalysis [13], [14], [15], [16] with α-diazo carbonyl compounds as substrates [11], [12], [13], [15], [16], we envisioned that electrophilic π-allyl Pd(II) intermediates [40] could be appropriate interceptive-coupling partners of protic oxonium ylides C. Herein, we disclose a three-component Rh(II)/Pd(0) dual-catalyzed oxy-allylations of alcohols, α-diazo esters, and allylic benzoates to produce α-ternary allylated carboxylic esters under redox-neutral conditions, involving the simultaneous formation of two new bonds (Csingle bondO and Csingle bondC) at the same carbon atom (Scheme 1b). Although possible in principle, some competitive reactions such as Osingle bondH insertion [34], Csingle bondO insertion [11], and cyclopropanation [41] offer formidable challenges in chemo-selectivity control.

Section snippets

Results and discussions

To validate the feasibility of the above hypothesis, the redox-compatible Rh(II)/Pd(0) dual catalytic system [13], [14], [15], [16] established by our group was employed to investigate the three-component allylic alkylations of 4-methoxybenzyl alcohol (1a), methyl α-phenyldiazoacetate (2a), and allyl benzoate (3a) as model substrates. After numerous trials (Table 1), we determined that the combination of Rh2(OAc)4, [PdCl(allyl)]2, and Xantphos gave the best results, providing the desired

Application and mechanism

The practical applicability of this approach was demonstrated in Scheme 4. Firstly, we applied the Rh(II)/Pd(0) dual-catalyzed three-component reaction of 1a, 2a, and 3a to the gram scale under the standard conditions. The acyclic α-ternary allylated carboxylic esters 4a could be isolated in a slightly lower yield (1.76 g, 87 % yield). Furthermore, the Wacker oxidation of 4a by using the Grubbs-Stoltz protocol afforded the aldehyde-selective product 9 in high yield [44]. Additionally, in the

Conclusion

In summary, we have realized a highly chemo-selective three-component oxy-allylation of α-diazo esters, alcohols, and allylic benzoates by employing Rh(II)/Pd(0) dual catalysis. The reaction occured by trapping active protic oxonium ylides with catalytic π-allyl Pd(II) intermediates. More remarkably, when alcohols were replaced with inexpensive and environmentally benign water. this transformation also proceeded well involving a different allylic migratory insertion of palladium-carbenes.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This work was supported by the National Natural Science Foundation of China (No. 22171228) and the Youth Training Project of Northwest A&F University (No. 2452017034). We sincerely thank Dr. Shaukat Ali (Institute of Chemical Sciences, University of Peshawar) for polishing English.

References (47)

  • S. Feng, F. Mo, Y. Xia, Z. Liu, Z. Liu, Y. Zhang, J. Wang, Rhodium(I)-Catalyzed C-C Bond Activation of...
  • P.-S. Wang et al.

    Palladium(II)/Lewis Acid Synergistically Catalyzed Allylic C-H Olefination

    Org. Lett.

    (2014)
  • B.N. Thomas et al.

    Z-Selective iridium-catalyzed cross-coupling of allylic carbonates and α-diazo esters

    Chem. Sci.

    (2018)
  • B. Song et al.

    Pd-Catalyzed Decarboxylative Olefination: Stereoselective Synthesis of Polysub-stituted Butadienes and Macrocyclic P-Glycoprotein Inhibitors

    J. Am. Chem. Soc.

    (2020)
  • Z.-S. Chen et al.

    Palladium-Catalyzed Divergent Reactions of α-Diazocarbonyl Compounds with Allylic Esters: Construction of Quaternary Carbon Centers

    Angew. Chem., Int. Ed.

    (2012)
  • Z.-S. Chen et al.

    Cooperative Pd(0)/Rh(II) Dual Catalysis: Interceptive Capturing of π-Allyl Pd(II) Complexes with α-Imino Rh(II) Carbenoids

    ACS Catal.

    (2016)
  • Z.-S. Chen et al.

    Rh(II)/Pd(0) Dual Catalysis: Regiodivergent Transformations of Alkylic Oxonium Ylides

    ACS Catal.

    (2017)
  • Z. Xuan et al.

    Cooperative Rh(II)/Pd(0) Dual-Catalyzed gem-Difunctionalization of α-Diazo Carbonyl Compounds: Construction of Quaternary Carbon Centers

    Eur. J. Org. Chem

    (2022)
  • M.-M. Li et al.

    Sequential visible-light photoactivation and palladium catalysis enabling enantioselective [4+2] cycloadditions

    J. Am. Chem. Soc.

    (2017)
  • Y. Wei et al.

    Enantioselective trapping of Pd-containing 1,5-dipoles by photogenerated ketenes: access to 7-membered lactones bearing chiral quaternary stereocenters

    J. Am. Chem. Soc.

    (2019)
  • Q.-L. Zhang et al.

    Palladium-catalyzed asymmetric [8+2] dipolar cycloadditions of vinyl carbamates and photogenerated ketenes

    Angew. Chem. Int. Ed.

    (2020)
  • L. Huang et al.

    Asymmetric Rh(II)/Pd(0) Relay Catalysis: Synthesis of α-Quaternary Chiral β-Lactams through Enantioselective C-H Insertion/Diastereoselective Allylation of Diazoamides

    ACS Catal.

    (2018)
  • B. Lu et al.

    Dirhodium(II)/Xantphos-Catalyzed Relay Carbene Insertion and Allylic Alkylation Process: Reaction Development and Mechanistic Insights

    J. Am. Chem. Soc.

    (2021)
  • Cited by (0)

    View full text