CC BY ND NC 4.0 · Synlett 2019; 30(04): 429-432
DOI: 10.1055/s-0037-1611663
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Copyright with the author

Air-Stable Secondary Phosphine Oxides for Nickel-Catalyzed Cross-Couplings of Aryl Ethers by C–O Activation

Debasish Ghorai
a  Institut für Organische und Biomolekulare Chemie, Georg-August-Universität, Tammannstraße 2, 37077 Göttingen, Germany   Email: Lutz.Ackermann@chemie.uni-goettingen.de
,
Joachim Loup
a  Institut für Organische und Biomolekulare Chemie, Georg-August-Universität, Tammannstraße 2, 37077 Göttingen, Germany   Email: Lutz.Ackermann@chemie.uni-goettingen.de
,
Giuseppe Zanoni
b  Department of Chemistry, University of Pavia, Viale Taramelli 10, 27100 Pavia, Italy
,
a  Institut für Organische und Biomolekulare Chemie, Georg-August-Universität, Tammannstraße 2, 37077 Göttingen, Germany   Email: Lutz.Ackermann@chemie.uni-goettingen.de
› Author Affiliations
Generous support by the European Research Council under the European Community’s Seventh Framework Program (FP7 2007-2013)/ERC Grant agreement no. 307535, and the Regione Lombardia – Cariplo Foundation is gratefully acknowledged.
Further Information

Publication History

Received: 02 December 2018

Accepted after revision: 06 January 2019

Publication Date:
15 January 2019 (eFirst)

 

Published as part of the 30 Years SYNLETT – Pearl Anniversary Issue

Abstract

Air- and moisture-stable secondary phosphine oxides (SPOs) enabled nickel-catalyzed Kumada–Corriu cross-couplings of various arylmethyl ethers at room temperature by challenging C–O activation.


#

Transition-metal-catalyzed cross-coupling reactions have emerged as a uniquely powerful tool for the assembly of substituted biaryl motifs.[1] Thus far, these cross-couplings have heavily relied on aryl halides as electrophilic coupling reagents. In contrast, easily accessible phenol-based electrophiles have recently undergone a renaissance as attractive alternatives.[2] On the basis of Wenkert’s early studies from 1979,[3] the considerable potential of phenol-derived substrates has only recently been fully recognized. Thus, versatile cross-couplings have been realized with challenging carbamates, carbonates, sulfamates, silyloxyarenes, esters and ethers, among others, prominently featuring nickel catalysis.[4] Generally, these nickel catalysts largely require electron-rich tertiary phosphines as stabilizing ligands to guarantee efficacy in the key C–O bond scission.[4] Unfortunately, these electron-rich tertiary phosphines are usually highly air-sensitive, with a documented half-life for the aerobic oxidation of tri-t-butyl-phosphine of a few minutes.[5]

The (heteroatom-substituted) secondary phosphine oxides (HA)SPOs represent uniquely powerful ancillary preligands for metal catalysis because of their unique features, including the air- and moisture-stable nature, among others.[6] Notably, air-stable SPOs undergo a self-assembly process in the presence of transition metals to generate a monoanionic bidentate chelate coordination environment (Scheme [1, a]).[6] While Ackermann and others have unraveled the considerable potential of SPO complexes towards a wealth of efficient cross-coupling reactions with various aryl halides,[7] the possibility of employing air-stable SPO preligands for more challenging C–O activations with aryl ethers has thus far proven elusive. Within our program on sustainable transition-metal-catalyzed transformations[8] and selective C–O activation,[9] we hence became attracted to probing the unprecedented use of air-stable SPOs preligands for cross-couplings with easily available aryl ethers, the result of which we report herein. Notable features of our findings include (i) air- and moisture-stable SPOs for efficient C–O activations, (ii) earth-abundant nickel catalysis, and (iii) exceedingly mild reaction conditions at room temperature (Scheme [1, b]).

Zoom Image
Scheme 1 (a) Self-assembly with SPOs, (b) nickel/SPO-catalyzed C–O activation

We initiated our studies by probing reaction conditions for the envisioned cross-coupling of ether 1a with Ni(acac)2 and Ph2P(O)H (L1) in toluene at a room temperature of 23 °C (Table [1], entry 1). Among a variety of preligands and solvents, the electron-rich HASPO L7 as well as (n-Bu)2P(O)H (L8) and THF gave optimal results, respectively (entries 2–13). NiCl2(DME) proved to be most effective (entries 14–17). It is noteworthy that under otherwise identical reaction conditions, the bidentate ligand dppp featured a significantly inferior performance (entry 18). A control experiment verified the essential role of the nickel catalyst (entry 19).

Table 1 Optimization of the Nickel/SPO-Catalyzed C–O Activation of Ether 1a a

Entry

Ni Catalyst

SPO

Solvent

Yield (%)

1

Ni(acac)2

L1

toluene

10

2

Ni(acac)2

L2

toluene

12

3

Ni(acac)2

L3

toluene

25

4

Ni(acac)2

L4

toluene

35

5

Ni(acac)2

L5

toluene

23

6

Ni(acac)2

L6

toluene

50

7

Ni(acac)2

L6

THF

64

8

Ni(acac)2

L1

THF

15

9

Ni(acac)2

L5

THF

21

10

Ni(acac)2

L3

THF

60

11

Ni(acac)2

L4

THF

48

12

Ni(acac)2

L7

THF

69

13

Ni(acac)2

L8

THF

83

14

Ni(OTf)2

L8

THF

53

15

NiBr2

L8

THF

n.r.

16

NiCl2(DME)

L8

THF

90

17

NiCl2(DME)

L8

THF

68b

18

NiCl2(DME)

dppp

THF

39c

19

L8

THF

n.r.

a Reaction conditions: 1a (0.50 mmol), p-TolMgBr (0.75 mmol), [Ni] (5.0 mol%), (HA)SPO (10 mol%), solvent (1.5 mL), 23 °C, 16 h; yield of isolated product given; n.r. = no reaction.

b SPO L8 (5.0 mol%).

c dppp (5.0 mol%).

Having the optimized reaction conditions for the nickel/SPO-catalyzed C–O activation in hand, we tested its versatility with a representative set of ethers 1 (Scheme [2]). Thus, a variety of naphthyl ethers 1 were identified as viable substrates for the Kumada–Corriu cross-coupling to deliver the desired products 2 with high catalytic efficacy. Notably, the nickel catalyst derived from the air-stable SPO L8 even proved amenable to the chemoselective synthesis of biaryl 2b and the sterically congested mesityl nucleophiles with comparable levels of activity (2d and 2i).

Zoom Image
Scheme 2 Scope of SPO/nickel-catalyzed C–O activation; a with NiCl2(DME) (10 mol%) and L8 (20 mol%)

Based on our previous literature reports,[6c] [d] [10] the working mode of the air-stable SPO-enabled C–O activation is suggested to initially involve the formation of complex 3 through self-assembly, along with the subsequent C–O activation by the key hetero-bimetallic intermediate 4 (Scheme [3]).

Zoom Image
Scheme 3 Plausible working mode of SPOs for C–O activation

In summary, we have reported on the first use of air-stable secondary phosphine oxides (SPOs) for challenging cross-couplings of aryl ethers by C–O activation.[11] Thus, in situ generated nickel catalysts enabled efficient Kumada–Corriu arylations of naphthyl ethers at room temperature, even when using sterically hindered aryl nucleophiles.


#

Supporting Information

  • References and Notes

  • 2 Kozhushkov SI, Potukuchi HK, Ackermann L. Catal. Sci. Technol. 2013; 3: 562
    • 3a Wenkert E, Michelotti EL, Swindell CS, Tingoli M. J. Org. Chem. 1984; 49: 4894
    • 3b Wenkert E, Michelotti EL, Swindell CS. J. Am. Chem. Soc. 1979; 101: 2246

      Representative reviews:
    • 4a Tobisu M, Chatani N. Acc. Chem. Res. 2015; 48: 1717
    • 4b Su B, Cao Z.-C, Shi Z.-J. Acc. Chem. Res. 2015; 48: 886
    • 4c Tollefson EJ, Hanna LE, Jarvo ER. Acc. Chem. Res. 2015; 48: 2344
    • 4d Tasker SZ, Standley EA, Jamison TF. Nature 2014; 509: 299
    • 4e Cornella J, Zarate C, Martin R. Chem. Soc. Rev. 2014; 43: 8081
    • 4f Li BJ, Yu DG, Sun CL, Shi ZJ. Chem. Eur. J. 2011; 17: 1728
    • 4g Rosen BM, Quasdorf KW, Wilson DA, Zhang N, Resmerita A.-M, Garg NK, Percec V. Chem. Rev. 2011; 111: 1346
    • 4h Yu D.-G, Li B.-J, Shi Z.-J. Acc. Chem. Res. 2010; 43: 1486

    • Selected examples:
    • 4i Wang T.-H, Ambre R, Wang Q, Lee W.-C, Wang P.-C, Liu Y, Zhao L, Ong T.-G. ACS Catal. 2018; 8: 11368
    • 4j Cao Z.-C, Luo Q.-Y, Shi Z.-J. Org. Lett. 2016; 18: 5978
    • 4k Zhang J, Xu J, Xu Y, Sun H, Shen Q, Zhang Y. Organometallics 2015; 34: 5792
    • 4l Iglesias MJ, Prieto A, Nicasio MC. Org. Lett. 2012; 14: 4318
    • 4m Xie L.-G, Wang Z.-X. Chem. Eur. J. 2011; 17: 4972
    • 4n Dankwardt JW. Angew. Chem. Int. Ed. 2004; 43: 2428

    • For general reviews on nickel catalyzed transformations, see:
    • 4o Castro LC. M, Chatani N. Chem. Lett. 2015; 44: 410
    • 4p Yamaguchi J, Muto K, Itami K. Eur. J. Org. Chem. 2013; 19
    • 4q Nakao Y. Chem. Rec. 2011; 11: 242, and references cited therein
  • 5 Netherton MR, Fu GC. Org. Lett. 2001; 3: 4295

    • Select reviews:
    • 6a Herault D, Nguyen DH, Nuel D, Buono G. Chem. Soc. Rev. 2015; 44: 2508
    • 6b Shaikh TM, Weng C.-M, Hong F.-E. Coord. Chem. Rev. 2012; 256: 771
    • 6c Ackermann L. Isr. J. Chem. 2010; 50: 652
    • 6d Ackermann L. Synthesis 2006; 1557
    • 6e Dubrovina NV, Börner A. Angew. Chem. Int. Ed. 2004; 43: 5883
    • 7a Ghorai D, Müller V, Keil H, Stalke D, Zanoni G, Tkachenko BA, Schreiner PR, Ackermann L. Adv. Synth. Catal. 2017; 359: 3137
    • 7b Hu C.-Y, Chen Y.-Q, Lin G.-Y, Huang M.-K, Chang Y.-C, Hong F.-E. Eur. J. Inorg. Chem. 2016; 3131
    • 7c Cano I, Tschan MJ. L, Martínez-Prieto LM, Philippot K, Chaudret B, van Leeuwen PW. N. M. Catal. Sci. Technol. 2016; 6: 3758
    • 7d Wellala NP, Guan H. Org. Biomol. Chem. 2015; 13: 10802
    • 7e Cano I, Huertos MA, Chapman AM, Buntkowsky G, Gutmann T, Groszewicz PB, van Leeuwen PW. N. M. J. Am. Chem. Soc. 2015; 137: 7718
    • 7f Ackermann L, Kapdi AR, Fenner S, Kornhaass C, Schulzke C. Chem. Eur. J. 2011; 17: 2965
    • 7g Ackermann L, Potukuchi HK, Kapdi AR, Schulzke C. Chem. Eur. J. 2010; 16: 3300
    • 7h Ackermann L, Vicente R, Hofmann N. Org. Lett. 2010; 11: 4274
    • 7i Achard T, Giordano L, Tenaglia A, Gimbert Y, Buono G. Organometallics 2010; 29: 3936
    • 7j Christiansen A, Selent D, Spannenberg A, Baumann W, Franke R, Börner A. Organometallics 2010; 29: 3139
    • 7k Christiansen A, Li C, Garland M, Selent D, Ludwig R, Spannenberg A, Baumann W, Franke R, Börner A. Eur. J. Org. Chem. 2010; 2733
    • 7l Ackermann L, Barfüßer S. Synlett 2009; 808
    • 7m Yang DX, Colletti SL, Wu K, Song M, Li GY, Shen HC. Org. Lett. 2009; 11: 381
    • 7n Billingsley KL, Buchwald SL. Angew. Chem., Int. Ed. Engl. 2008; 47: 4695
    • 7o Ackermann L, Born R, Spatz JH, Meyer D. Angew. Chem. Int. Ed. 2005; 44: 7216
    • 8a Gandeepan P, Müller T, Zell D, Cera G, Warratz S, Ackermann L. Chem. Rev. 2019; DOI: in press; doi: 10 1021/acs.chemrev.8b00507.
    • 8b Lorion MM, Maindan K, Kapdi AR, Ackermann L. Chem. Soc. Rev. 2017; 46: 7399
    • 8c Moselage M, Li J, Ackermann L. ACS Catal. 2016; 6: 498
    • 8d Liu W, Ackermann L. ACS Catal. 2016; 6: 3743
    • 9a Sauermann N, Loup J, Kootz D, Berkessel A, Ackermann L. Synthesis 2017; 49: 3476
    • 9b Song W, Ackermann L. Angew. Chem. Int. Ed. 2012; 51: 8251
    • 9c Ackermann L, Pospech J, Potukuchi HK. Org. Lett. 2012; 14: 2146
    • 9d Ackermann L, Althammer A, Born R. Angew. Chem. Int. Ed. 2006; 45: 2619
    • 9e Moselage M, Sauermann N, Richter S. C, Ackermann L. Angew. Chem. Int. Ed. 2015; 54: 6352
  • 10 Ackermann L. Synlett 2007; 507
  • 11 Representative Experimental Procedure and Characterization DataA mixture of 2-methoxynaphthalene (1a) (79 mg, 0.5 mmol), [NiCl2(DME)] (6.0 mg, 0.025 mmol, 5.0 mol%), and L8 (8.0 mg, 0.05 mmol, 10.0 mol%) was stirred in THF (1.5 mL) for 2 min at ambient temperature under N2. Then, p-TolMgBr (1.0 m in THF, 0.75 mL, 0.75 mmol) was added, and the resulting solution was stirred for 16 h at ambient temperature. To the reaction was added aqueous HCl (1 m, 5 mL) and then EtOAc (5 mL), and the separated aqueous phase was extracted with EtOAc (2 × 5 mL). The combined organic layers were dried with anhydrous Na2SO4 and concentrated in vacuo. The remaining residue was purified by column chromatography on silica gel (n-hexane) to yield 2a (98 mg, 90%) as a colorless solid. Mp 93–95 °C. IR (ATR): 3054, 3024, 1501, 1351, 893, 856, 811, 748 cm−1. 1H NMR (300 MHz, CDCl3): δ = 8.14 (d, J = 1.4 Hz, 1 H), 8.03–7.93 (m, 3 H), 7.85 (dd, J = 8.5, 1.9 Hz, 1 H), 7.74 (d, J = 8.1 Hz, 2 H), 7.64–7.54 (m, 2 H), 7.40 (dd, J = 8.5, 0.6 Hz, 2 H), 2.53 (s, 3 H). 13C NMR (75 MHz, CDCl3): δ = 138.5 (Cq), 138.3 (Cq), 137.2 (Cq), 133.8 (Cq), 132.5 (Cq), 129.6 (CH), 128.4 (CH), 128.2 (CH), 127.7 (CH), 127.3 (CH), 126.3 (CH), 125.8 (CH), 125.6 (CH), 125.5 (CH), 21.2 (CH3). MS (EI): m/z (relative intensity) = 218 [M]+ (100), 217 (41), 202 (35). HRMS (EI): m/z [M]+ calcd for [C17H14]+: 218.1096; found: 218.1094.

  • References and Notes

  • 2 Kozhushkov SI, Potukuchi HK, Ackermann L. Catal. Sci. Technol. 2013; 3: 562
    • 3a Wenkert E, Michelotti EL, Swindell CS, Tingoli M. J. Org. Chem. 1984; 49: 4894
    • 3b Wenkert E, Michelotti EL, Swindell CS. J. Am. Chem. Soc. 1979; 101: 2246

      Representative reviews:
    • 4a Tobisu M, Chatani N. Acc. Chem. Res. 2015; 48: 1717
    • 4b Su B, Cao Z.-C, Shi Z.-J. Acc. Chem. Res. 2015; 48: 886
    • 4c Tollefson EJ, Hanna LE, Jarvo ER. Acc. Chem. Res. 2015; 48: 2344
    • 4d Tasker SZ, Standley EA, Jamison TF. Nature 2014; 509: 299
    • 4e Cornella J, Zarate C, Martin R. Chem. Soc. Rev. 2014; 43: 8081
    • 4f Li BJ, Yu DG, Sun CL, Shi ZJ. Chem. Eur. J. 2011; 17: 1728
    • 4g Rosen BM, Quasdorf KW, Wilson DA, Zhang N, Resmerita A.-M, Garg NK, Percec V. Chem. Rev. 2011; 111: 1346
    • 4h Yu D.-G, Li B.-J, Shi Z.-J. Acc. Chem. Res. 2010; 43: 1486

    • Selected examples:
    • 4i Wang T.-H, Ambre R, Wang Q, Lee W.-C, Wang P.-C, Liu Y, Zhao L, Ong T.-G. ACS Catal. 2018; 8: 11368
    • 4j Cao Z.-C, Luo Q.-Y, Shi Z.-J. Org. Lett. 2016; 18: 5978
    • 4k Zhang J, Xu J, Xu Y, Sun H, Shen Q, Zhang Y. Organometallics 2015; 34: 5792
    • 4l Iglesias MJ, Prieto A, Nicasio MC. Org. Lett. 2012; 14: 4318
    • 4m Xie L.-G, Wang Z.-X. Chem. Eur. J. 2011; 17: 4972
    • 4n Dankwardt JW. Angew. Chem. Int. Ed. 2004; 43: 2428

    • For general reviews on nickel catalyzed transformations, see:
    • 4o Castro LC. M, Chatani N. Chem. Lett. 2015; 44: 410
    • 4p Yamaguchi J, Muto K, Itami K. Eur. J. Org. Chem. 2013; 19
    • 4q Nakao Y. Chem. Rec. 2011; 11: 242, and references cited therein
  • 5 Netherton MR, Fu GC. Org. Lett. 2001; 3: 4295

    • Select reviews:
    • 6a Herault D, Nguyen DH, Nuel D, Buono G. Chem. Soc. Rev. 2015; 44: 2508
    • 6b Shaikh TM, Weng C.-M, Hong F.-E. Coord. Chem. Rev. 2012; 256: 771
    • 6c Ackermann L. Isr. J. Chem. 2010; 50: 652
    • 6d Ackermann L. Synthesis 2006; 1557
    • 6e Dubrovina NV, Börner A. Angew. Chem. Int. Ed. 2004; 43: 5883
    • 7a Ghorai D, Müller V, Keil H, Stalke D, Zanoni G, Tkachenko BA, Schreiner PR, Ackermann L. Adv. Synth. Catal. 2017; 359: 3137
    • 7b Hu C.-Y, Chen Y.-Q, Lin G.-Y, Huang M.-K, Chang Y.-C, Hong F.-E. Eur. J. Inorg. Chem. 2016; 3131
    • 7c Cano I, Tschan MJ. L, Martínez-Prieto LM, Philippot K, Chaudret B, van Leeuwen PW. N. M. Catal. Sci. Technol. 2016; 6: 3758
    • 7d Wellala NP, Guan H. Org. Biomol. Chem. 2015; 13: 10802
    • 7e Cano I, Huertos MA, Chapman AM, Buntkowsky G, Gutmann T, Groszewicz PB, van Leeuwen PW. N. M. J. Am. Chem. Soc. 2015; 137: 7718
    • 7f Ackermann L, Kapdi AR, Fenner S, Kornhaass C, Schulzke C. Chem. Eur. J. 2011; 17: 2965
    • 7g Ackermann L, Potukuchi HK, Kapdi AR, Schulzke C. Chem. Eur. J. 2010; 16: 3300
    • 7h Ackermann L, Vicente R, Hofmann N. Org. Lett. 2010; 11: 4274
    • 7i Achard T, Giordano L, Tenaglia A, Gimbert Y, Buono G. Organometallics 2010; 29: 3936
    • 7j Christiansen A, Selent D, Spannenberg A, Baumann W, Franke R, Börner A. Organometallics 2010; 29: 3139
    • 7k Christiansen A, Li C, Garland M, Selent D, Ludwig R, Spannenberg A, Baumann W, Franke R, Börner A. Eur. J. Org. Chem. 2010; 2733
    • 7l Ackermann L, Barfüßer S. Synlett 2009; 808
    • 7m Yang DX, Colletti SL, Wu K, Song M, Li GY, Shen HC. Org. Lett. 2009; 11: 381
    • 7n Billingsley KL, Buchwald SL. Angew. Chem., Int. Ed. Engl. 2008; 47: 4695
    • 7o Ackermann L, Born R, Spatz JH, Meyer D. Angew. Chem. Int. Ed. 2005; 44: 7216
    • 8a Gandeepan P, Müller T, Zell D, Cera G, Warratz S, Ackermann L. Chem. Rev. 2019; DOI: in press; doi: 10 1021/acs.chemrev.8b00507.
    • 8b Lorion MM, Maindan K, Kapdi AR, Ackermann L. Chem. Soc. Rev. 2017; 46: 7399
    • 8c Moselage M, Li J, Ackermann L. ACS Catal. 2016; 6: 498
    • 8d Liu W, Ackermann L. ACS Catal. 2016; 6: 3743
    • 9a Sauermann N, Loup J, Kootz D, Berkessel A, Ackermann L. Synthesis 2017; 49: 3476
    • 9b Song W, Ackermann L. Angew. Chem. Int. Ed. 2012; 51: 8251
    • 9c Ackermann L, Pospech J, Potukuchi HK. Org. Lett. 2012; 14: 2146
    • 9d Ackermann L, Althammer A, Born R. Angew. Chem. Int. Ed. 2006; 45: 2619
    • 9e Moselage M, Sauermann N, Richter S. C, Ackermann L. Angew. Chem. Int. Ed. 2015; 54: 6352
  • 10 Ackermann L. Synlett 2007; 507
  • 11 Representative Experimental Procedure and Characterization DataA mixture of 2-methoxynaphthalene (1a) (79 mg, 0.5 mmol), [NiCl2(DME)] (6.0 mg, 0.025 mmol, 5.0 mol%), and L8 (8.0 mg, 0.05 mmol, 10.0 mol%) was stirred in THF (1.5 mL) for 2 min at ambient temperature under N2. Then, p-TolMgBr (1.0 m in THF, 0.75 mL, 0.75 mmol) was added, and the resulting solution was stirred for 16 h at ambient temperature. To the reaction was added aqueous HCl (1 m, 5 mL) and then EtOAc (5 mL), and the separated aqueous phase was extracted with EtOAc (2 × 5 mL). The combined organic layers were dried with anhydrous Na2SO4 and concentrated in vacuo. The remaining residue was purified by column chromatography on silica gel (n-hexane) to yield 2a (98 mg, 90%) as a colorless solid. Mp 93–95 °C. IR (ATR): 3054, 3024, 1501, 1351, 893, 856, 811, 748 cm−1. 1H NMR (300 MHz, CDCl3): δ = 8.14 (d, J = 1.4 Hz, 1 H), 8.03–7.93 (m, 3 H), 7.85 (dd, J = 8.5, 1.9 Hz, 1 H), 7.74 (d, J = 8.1 Hz, 2 H), 7.64–7.54 (m, 2 H), 7.40 (dd, J = 8.5, 0.6 Hz, 2 H), 2.53 (s, 3 H). 13C NMR (75 MHz, CDCl3): δ = 138.5 (Cq), 138.3 (Cq), 137.2 (Cq), 133.8 (Cq), 132.5 (Cq), 129.6 (CH), 128.4 (CH), 128.2 (CH), 127.7 (CH), 127.3 (CH), 126.3 (CH), 125.8 (CH), 125.6 (CH), 125.5 (CH), 21.2 (CH3). MS (EI): m/z (relative intensity) = 218 [M]+ (100), 217 (41), 202 (35). HRMS (EI): m/z [M]+ calcd for [C17H14]+: 218.1096; found: 218.1094.

 
Zoom Image
Scheme 1 (a) Self-assembly with SPOs, (b) nickel/SPO-catalyzed C–O activation
Zoom Image
Scheme 2 Scope of SPO/nickel-catalyzed C–O activation; a with NiCl2(DME) (10 mol%) and L8 (20 mol%)
Zoom Image
Scheme 3 Plausible working mode of SPOs for C–O activation