Synlett 2017; 28(18): 2435-2438
DOI: 10.1055/s-0036-1590903
cluster
© Georg Thieme Verlag Stuttgart · New York

Design and Synthesis of Enantiopure Tetrakis(pentafluorophenyl) Borate Analogues for Asymmetric Counteranion Directed Catalysis

Chandra Kanta De, Raja Mitra, Benjamin List*
  • Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany   Email: list@mpi-muelheim.mpg.de
Funding from the Max-Planck-Society and the European Research Council (Advanced Grant CHAOS) is gratefully acknowledged.
Further Information

Publication History

Received: 13 June 2017

Accepted after revision: 16 August 2017

Publication Date:
30 August 2017 (eFirst)

Published as part of the Cluster Silicon in Synthesis and Catalysis

Abstract

The design and five-step synthesis of chiral tetrakis(pentafluo­rophenyl) borate analogues from commercially available enantiopure BINOL is described. The chiral anions have been tested in a catalytic asymmetric Mukaiyama aldol reaction.

 
  • References and Notes

    • 1a Mahlau M. List B. Angew. Chem. Int. Ed. 2013; 52: 518

    • Also see:
    • 1b Lacour J. Hebbe-Viton V. Chem. Soc. Rev. 2003; 32: 373
    • 1c Phipps RJ. Hamilton GL. Toste FD. Nat. Chem. 2012; 4: 603
    • 1d Brack K. Jacobsen EN. Angew. Chem. Int. Ed. 2013; 52: 534

    • For early studies:
    • 1e Llewellyn DB. Adamson D. Arndtsen BA. Org. Lett. 2000; 2: 4165
    • 1f Carter C. Fletcher S. Nelson A. Tetrahedron: Asymmetry 2003; 14: 1995
    • 2a Akiyama T. Mori K. Chem. Rev. 2015; 115: 9277
    • 2b Parmar D. Sugiono E. Raja S. Rueping M. Chem. Rev. 2014; 114: 9047
    • 2c Asymmetric Organocatalysis Workbench Edition . List B. Maruoka K. Thieme; Stuttgart; 2012
    • 2d Terada M. Synthesis 2010; 1929
    • 2e Kampen D. Reisinger CM. List B. Top. Curr. Chem. 2010; 291: 395
    • 2f Akiyama T. Chem. Rev. 2007; 107: 5744

    • Also see:
    • 2g Mao Z. Mo F. Lin X. Synlett 2016; 546
    • 2h Tay J.-H. Nagorny P. Synlett 2016; 551
    • 2i Lai Z. Sun J. Synlett 2016; 555
    • 2j Lebée C. Blanchard F. Masson G. Synlett 2016; 559
    • 2k Qin L. Wang P. Zhang Y. Ren Z. Zhang X. Da C.-S. Synlett 2016; 571
    • 2l Jiang F. Zhang Y.-C. Yang X. Zhu Q.-N. Shi F. Synlett 2016; 575
    • 2m Kanomata K. Terada M. Synlett 2016; 581
    • 2n Zhou Y. Liu X.-W. Gu Q. You S.-L. Synlett 2016; 586
    • 2o Monaco MR. Properzi R. List B. Synlett 2016; 591
    • 2p Hatano M. Ishihara H. Goto Y. Ishihara K. Synlett 2016; 564
    • 2q Guo Y. Gao Z. Meng X. Huang G. Zhong H. Yu H. Ding X. Tang H. Zou C. Synlett 2017; DOI: DOI: 10.1055/s-0036-1589504.
    • 3a Rueping M. Nachtsheim BJ. Ieawsuwan W. Atodiresei I. Angew. Chem. Int. Ed. 2011; 50: 6706
    • 3b Akiyama T. Mori K. Chem. Rev. 2015; 115: 9277
    • 3c James T. van Gemmeren M. List B. Chem. Rev. 2015; 115: 9388
    • 3d Coric I. List B. Nature 2012; 483: 315
    • 3e Gatzenmeier T. van Gemmeren M. Xie Y. Höfler D. Leutzsch M. List B. Science 2016; 351: 949
    • 3f Kaib PS. J. Schreyer L. Lee S. Properzi R. List B. Angew. Chem. Int. Ed. 2016; 55: 13200

    • Also see:
    • 3g Kaib PS. J. List B. Synlett 2016; 27: 156
    • 3h Lee S. Kaib PS. J. List B. Synlett 2017; 28: 1478
    • 4a Großekappenberg H. Reißmann M. Schmidtmann M. Müller T. Organometallics 2015; 34: 4952
    • 4b Massey AG. Park AJ. J. Organomet. Chem. 1964; 2: 245
    • 4c Hiroshi K. Takaaki S. Hidetoshi I. Masaji Y. Chem. Lett. 1981; 10: 579
    • 4d Strauss SH. Chem. Rev. 1993; 93: 927
    • 4e Krossing I. Raabe I. Angew. Chem. Int. Ed. 2004; 43: 2066
    • 4f Bochmann M. Coord. Chem. Rev. 2009; 253: 2000
    • 4g Pollak D. Goddard R. Pörschke K.-R. J. Am. Chem. Soc. 2016; 138: 9444
    • 5a Barbarich TJ. Handy ST. Miller SM. Anderson OP. Grieco PA. Strauss SH. Organometallics 1996; 15: 3776
    • 5b Moss S. King BT. de Meijere A. Kozhushkov SI. Eaton PE. Michl J. Org. Lett. 2001; 3: 2375
    • 5c Anderson LL. Arnold J. Bergman RG. J. Am. Chem. Soc. 2005; 127: 14542
    • 5d Chen M.-C. Roberts JA. S. Seyam AM. Li L. Zuccaccia C. Stahl NG. Marks TJ. Organometallics 2006; 25: 2833
    • 5e Roberts JA. S. Chen M.-C. Seyam AM. Li L. Zuccaccia C. Stahl NG. Marks TJ. J. Am. Chem. Soc. 2007; 129: 12713
  • 6 Uozumi Y. Suzuki N. Ogiwara A. Hayashi T. Tetrahedron 1994; 50: 4293
  • 7 García-García P. Lay F. García-García P. Rabalakos C. List B. Angew. Chem. Int. Ed. 2009; 48: 4363
  • 8 During the preparation of this manuscript, similar work appeared: Pommerening P. Mohr J. Friebel J. Oestreich M. Eur. J. Org. Chem. 2017; 2312
  • 9 Synthesis of the Zn-reagent: A flame-dried 50 mL Schlenk flask was charged with 1,2,3,5-tetrafluorobenzene (4.0 mmol, 1.0 equiv) and a magnetic stirring bar. To this Schlenk flask, anhydrous THF (20 mL) was added under an argon atmosphere. The mixture was stirred at r.t. for 5 min and then cooled to –78 °C. After 30 min at –78 °C, n-BuLi (2.5 M in hexane, 1.65 mL, 4.1 mmol, 1.02 equiv) was slowly added through the cold side-wall of the flask under an argon atmosphere (Note: direct addition of n-BuLi to the cold mixture could lead to an explosive reaction). The reaction mixture was stirred at –78 °C for 1 h and freshly dried ZnBr2 (1.0 M in THF, 4.2 mL, 4.2 mmol, 1.05 equiv) was slowly added to the reaction mixture and stirring was continued for 20 min. The dry-ice bath was removed and the reaction mixture was allowed to warm to r.t. After 20 min at r.t., ca. 15 mL of THF was removed under reduced pressure (Schlenk technique). This Zn-reagent was directly used for the next step.
  • 10 General Procedure for Negishi Cross-Coupling: A flame-dried 25 mL Schlenk flask was charged with compound (S)-1 (1.0 mmol, 1.0 equiv) and a magnetic stirring bar. To this flask, the freshly prepared Zn-reagent (4.0 mmol, 4.0 equiv) was transferred under an argon atmosphere. The mixture was degassed (three times) and Pd(PPh3)4 (10 mol%, 0.1 mmol, 0.1 equiv) was added. The reaction mixture was heated to 100 °C for 24 h, then cooled to r.t. and treated with saturated aq. NH4Cl. The crude reaction mixture was extracted with CH2Cl2 (3 × 10 mL), dried over Na2SO4, and concentrated under reduced pressure. Purification was performed by SiO2 column chromatography using 10% CH2Cl2/i-hexanes. (S)-2a: Prepared according to the general procedure as a colorless solid in 72% yield. 1H NMR (500 MHz, CD2Cl2): δ = 8.11 (d, J = 8.5 Hz, 1 H), 8.03 (d, J = 8.3 Hz, 1 H), 7.85 (d, J = 8.2 Hz, 2 H), 7.60–7.54 (m, 1 H), 7.52 (d, J = 8.5 Hz, 1 H), 7.50–7.45 (m, 1 H), 7.44–7.38 (m, 2 H), 7.36–7.29 (m, 1 H), 7.29–7.21 (m, 3 H), 6.88–6.77 (m, 1 H). (S)-2b: Prepared according to the general procedure as a colorless solid in 81% yield. Compound (S)-2b exists as a 1:1 mixture of rotamers. 1H NMR (500 MHz, CD2Cl2): δ = 8.09 (d, J = 8.5 Hz, 2 H), 8.02 (d, J = 8.2, Hz, 2 H), 7.88–7.80 (m, 4 H), 7.60–7.53 (m, 2 H), 7.53–7.37 (m, 8 H), 7.34–7.28 (m, 2 H), 7.28–7.18 (m, 6 H), 6.67–6.58 (m, 1 H), 6.52–6.39 (m, 1 H).
  • 11 General Procedure for Synthesis of 4: A flame-dried 25 mL Schlenk flask was charged with compound (S)-2a (1.0 mmol, 1.0 equiv) and a magnetic stirring bar. To this flask, anhydrous Et2O (5 mL) was added under an argon atmosphere. The mixture was stirred at r.t. for 5 min to dissolve the substrate and was then cooled to –78 °C. After 30 min at –78 °C, n-BuLi (2.5 M in hexane, 0.42 mL, 1.05 mmol, 1.05 equiv) was slowly added through the cold side-wall of the flask. The reaction mixture was stirred at –78 °C for 4 h. After 4 h, BCl3 (1.0 M in heptane, 0.2 mL, 0.2 mmol, 0.2 equiv) was slowly added to the reaction mixture and warmed to r.t. over 4 h and the stirring was continued for overnight. Then the mixture was cooled and reaction was subsequently quenched with saturated NaCl (aq.). The crude reaction mixture was extracted with CH2Cl2 (3 × 10 mL), dried over Na2SO4, and concentrated under reduced pressure. Purification was performed by SiO2 column chromatography using 10% MeOH/CH2Cl2. The purified product was dissolved in CH2Cl2 and 10 mL saturated NaCl (aq.) solution was added and the reaction mixture was vigorously stirred for 20 min at r.t. It was then extracted with CH2Cl2 (3 × 10 mL), dried over Na2SO4, and concentrated under reduced pressure. 4a: Prepared according to the general procedure as a white solid in 52% yield. 11B NMR (160 MHz, CD2Cl2): δ = –17.12. HRMS (ESI): m/z calcd. for C104H52BF16 [M]: 1615.39205; found 1615.39121. 4b: Prepared according to the general procedure as a white solid in 41% yield. 11B NMR (160 MHz, CD2Cl2): δ = –17.22. HRMS (ESI): m/z calcd. for C104H52BF16 [M]: 1615.39205; found 1615.39121.
  • 12 General Procedure for Mukaiyama Aldol Reaction: An oven-dried 2 mL GC vial was charged with catalyst 4 (4.1 mg, 0.0025 mmol, 0.1 equiv), aldehyde 5 (3.9 mg, 0.025 mmol, 1.0 equiv) and a magnetic stirring bar. To this vial, solvent (0.25 mL) was added and the mixture was stirred at r.t. for 5 min. Then the mixture was cooled to the reaction temperature. Silyl ketene acetal 6 (6.4 μL, 0.031 mmol, 1.25 equiv) was added followed by TMSCl (0.15–0.5 equiv) under an argon atmosphere. After consumption of aldehyde, the reaction was quenched with saturated NaHCO3 (aq.) solution and the crude mixture was directly purified without further work-up on a SiO2 preparative TLC using 5–20% EtOAc/i-hexanes (v/v) as eluent.