Download PDF
Synlett 2023; 34(12): 1381-1384
DOI: 10.1055/s-0042-1752655
cluster
Special Issue Honoring Masahiro Murakami’s Contributions to Science

Nickel-Сatalyzed Carbon–Selenium Bond Formations under Mild Conditions

Serik Zhumagazy‡
,
Chen Zhu‡
,
Huifeng Yue∗
,
Magnus Rueping  ∗

This work was financially supported by the King Abdullah University of Science and Technology (KAUST), Saudi Arabia, Office of Sponsored Research (URF/1/4405).
› Further Information
 
 PDF Download Permissions and Reprints All articles of this category


Abstract

A nickel-catalyzed C–Se cross-coupling between aryl iodides and selenols is described. The newly developed catalytic methodology offers facile access to various unsymmetrical selenium-containing motifs. The reaction features excellent functional group tolerance, wide substrate scope, good efficiency, and operates under mild reaction conditions. Notably, this protocol could be readily scaled up to gram scale without the loss of yield.


#

Key words

nickel catalysis - C–Se bond formation - aryl halide - cross-coupling

Unsymmetrical aryl and alkyl selenides are a significant class of organic molecules due to their wide applications. These type of compounds have been successfully utilized in materials science,[1] polymer chemistry,[2] as well as catalysis.[3] Organoselenium compounds are particularly prevalent in pharmaceutical industry and they have been proven to possess antitumor,[4] anti-inflammatory,[5] and antimicrobial[6] activity. Over the past decades, substantial progress has been made for the incorporation of selenium into organic compounds and selenylation reactions based on transition-metal catalysis involving palladium[7] or copper[8] catalysts (Scheme [1a]) have been reported. Over the past decade, nickel catalysis has drawn great attention due to its low-cost and high efficiency.[9] Very recently, Xu, Yu, and co-workers realized the synthesis of various selenides by nickel-catalyzed intramolecular decarbonylative reaction of aryl selenoesters.[10] Also, Shao et al. reported a nickel-catalyzed cross-electrophile coupling of aryl iodides and benzeneselenosulfonates[11] (Scheme [1b]). These C–Se bond construction methods proceeded mainly under elevated temperature, in the presence of strong bases or stoichiometric amounts of metal reductant. Given the significance of selenium-containing moieties, the development of simple, mild, and efficient selenylation reactions is still of importance.

Zoom Image
Scheme 1 Previously reported selenylation methods and the novel Ni-catalyzed C–Se cross-coupling reaction

In light of increasing attention to environmentally friendly C–Se cross-coupling alternatives, Kundu comprehensively discussed recent advances on transition-metal free C–Se/Te bond-formation reactions, including unconventional methods such as microwave- and ultrasound-assisted synthesis and ball-milling strategies.[12] In particular, Laulhé[13] and Rueping[14] independently developed photoinduced C–Se cross-coupling reactions applying electron donor–acceptor (EDA) concept, accessing numerous diaryl selenides (Scheme [1c]). Although such transition-metal-free protocols represent a sustainable tool towards the synthesis of selenides, the limited substrate scope, and demand of pre-functionalized substrates (diazonium salts,[15] electrophilic aryl selenium halides,[16] or cyanides,[5] etc.) limit the practicality of these methodologies. However, if compared to most other methods transition-metal-catalyzed C–heteroatom bond-formation reactions are still advantageous due to their high efficiency, reliable catalytic reactivity, and good functional group tolerance.[17]

As a part of our continuing studies in the field of C–heteroatom bond construction,[18] we herein disclose a simple and robust nickel-catalyzed C–Se cross-coupling reaction from readily available aryl iodides (Scheme [1d]). This catalytic protocol offers efficient approach to access aryl–aryl and aryl–alkyl selenides under mild conditions with excellent functional group tolerance.

To test the feasibility of the nickel-catalyzed selenylation reaction, we commenced the optimization studies by choosing the reaction of 4-iodoanisole (1a) and phenylselenol (2a) as a model reaction (Table [1]). After extensive screening, the optimal reaction conditions were identified as follows: Ni(COD)2 as catalyst, L1 (4,4′-di-tert-butyl-2,2′-dipyridyl) as ligand, DBU as base in MeCN at 40 °C for 12 h. Initially, when the reaction was conducted at room temperature, 82% yield of the desired product was obtained (entry 1). To our delight, the reaction at slightly elevated temperature (40 °C) increased the yield of 3a to 92% (entry 2).

Table 1 Optimization of the Nickel-Catalyzed Selenylation Reaction of Aryl Iodidesa

Entry

Variables

Yield (%)b

 1

none

82

 2

40 °C

92

 3

NiCl2·dme

NR

 4

NiBr2·dtbbpy

NR

 5

DMA as solvent

29

 6

THF as solvent

NR

 7

DMF as solvent

NR

 8

toluene as solvent

NR

 9

L2 instead of L1

60

10

L3 instead of L1

67

11

L4 instead of L1

38

12

L5 instead of L1

NR

13

K3PO4 as base

80

14

Et3N as base

20

15

BTMG as base

15

16

w/o Ni

NR

17

w/o ligand

NR

18

w/o base

NR

a Reaction conditions: 1a (0.40 mmol), 2a (0.20 mmol), DBU (2 equiv) in MeCN (1 mL) at rt for 12 h.

b GC Yields using dodecane as internal standard.

The reaction failed to work when Ni(II) catalysts such as NiCl2·dme and NiBr2·dtbbpy were applied (entries 3 and 4), indicating that Ni(0) species is crucial for this C–Se cross-coupling transformation. Changing the solvent from MeCN to DMA considerably decreased the yield, and solvents such as DMF, THF, and toluene showed no product formation (entries 5–8). When other bidentate ligands were utilized instead of the dtbbpy ligand, the reaction gave lower yields (entries 9–11), whereas the terpyridine ligand failed to provide product (entry 12). The use of K3PO4 as base furnished 3a in 80% yield (entry 13). However, application of other organic bases such as Et3N and BTMG dramatically diminished the reaction performance (entries 14, 15). The control experiments demonstrated that nickel, ligand, and base are all essential for the success of this new nickel-catalyzed selenylation protocol (entries 16–18).

With the optimized reaction conditions in hand, we started the investigation of the reaction scope of this newly developed nickel-catalyzed C–Se cross-coupling protocol with different aryl iodides (Scheme [2]). Gratifyingly, a wide array of substrates bearing electron-donating (3a–g) groups showed good compatibility in this selenylation reaction. Remarkably, aryl iodides containing alkyl moieties (3h–j) provided the desired products in quantitative yields. Electron-deficient aryl iodides with functional groups such as ester (3k,l), nitrile (3m–o), and reactive aldehyde (3p) could be converted into the corresponding diarylselenide products smoothly. We were pleased to find that steric hindrance has small influence on the reaction efficiency (3f,o,r). Moreover, highly conjugated biphenyl aryl iodide and naphthyl iodide (3q,r) furnished the desired products in 97% and 80% yield, respectively. Notably, heterocyclic pyridine and thiophene substrates also underwent this selenylation reaction with moderate to good efficiency (3s–u,z). Importantly, this protocol can be successfully applied to various aryl/alkyl selenides as well (3t–ac). However, the aryl bromides and aryl chlorides failed to give the desired products.

Zoom Image
Scheme 2 Scope of the selenylation reaction. Reagents and conditions: 1 (0.4 mmol), 2 (0.2 mmol), Ni(COD)2 (10 mol%), dtbbpy (10 mol%), DBU (2 equiv) in MeCN (1 mL) at 40 °C for 12 h; yield after purification. a The corresponding selenolate was used without the addition of DBU. b Reaction performed in 0.1 mmol scale.

To illustrate the applicability of this novel C–Se cross-coupling reaction, we conducted the gram-scale experiment of 1a and 2a with standard conditions (Scheme [3]). The diaryl selenide 3a was achieved in 82% yield (1.30 g).

Zoom Image
Scheme 3 Gram-scale selenylation reaction

A plausible mechanism for the nickel-catalyzed C–Se cross-coupling reaction is proposed in Scheme [4]. The catalytic cycle starts from the rapid oxidative addition of aryl iodide with the in situ formed Ni(0) catalyst A to generate a Ni(II) species B. Subsequently, transmetalation of intermediate B with deprotonated selenol takes place to give a new Ni(II) intermediate C, followed by reductive elimination to deliver the desired diaryl selenide product along with the regeneration of Ni(0) complex A; thus closing the catalytic cycle.

Zoom Image
Scheme 4 Proposed mechanism of the Ni-catalyzed C–Se cross-coupling reaction

In summary, we report a nickel catalyzed C–Se bond construction reaction via the cross-coupling of aryl halides with aryl and alkyl selenides.[19] Different from previous reports on diaryl selenide synthesis, this new catalytic reaction features excellent tolerance towards different functional groups and general applicability. In addition, it exhibits high atom economy due to the minimal use of additives and proceeds under mild reaction conditions from readily available substrates.


#

Conflict of Interest

The authors declare no conflict of interest.

Supporting Information

    Supporting information for this article is available online at https://doi-org.accesdistant.sorbonne-universite.fr/10.1055/s-0042-1752655.
  • Supporting Information

Corresponding Authors

Magnus Rueping
King Abdullah University of Science and Technology (KAUST)
KAUST Catalysis Center (KCC), Thuwal 23955-6900
Saudi Arabia   

Huifeng Yue
King Abdullah University of Science and Technology (KAUST)
KAUST Catalysis Center (KCC), Thuwal 23955-6900
Saudi Arabia   

Publication History

Received: 22 January 2023

Accepted after revision: 27 February 2023

Article published online:
31 March 2023

© 2023. Thieme. All rights reserved

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany


   Permissions and Reprints All articles of this category
Zoom Image
Scheme 1 Previously reported selenylation methods and the novel Ni-catalyzed C–Se cross-coupling reaction
Zoom Image
Scheme 2 Scope of the selenylation reaction. Reagents and conditions: 1 (0.4 mmol), 2 (0.2 mmol), Ni(COD)2 (10 mol%), dtbbpy (10 mol%), DBU (2 equiv) in MeCN (1 mL) at 40 °C for 12 h; yield after purification. a The corresponding selenolate was used without the addition of DBU. b Reaction performed in 0.1 mmol scale.
Zoom Image
Scheme 3 Gram-scale selenylation reaction
Zoom Image
Scheme 4 Proposed mechanism of the Ni-catalyzed C–Se cross-coupling reaction