Download PDF
Synlett 2002(12): 2049-2053
DOI: 10.1055/s-2002-35603
LETTER
© Georg Thieme Verlag Stuttgart · New York

Polymer-Supported 2,2′-Bis(oxazolin-2-yl)-1,1′-binaphthyls (Boxax): Immobilized Chiral Ligands for Asymmetric Wacker-Type Cyclizations

Heiko Hocke, Yasuhiro Uozumi*
Institute for Molecular Science, Nishi-Gonaka 38, Myodaiji, Okazaki 444-8585, Japan
e-Mail: uo@ims.ac.jp;
Further Information

Publication History

Received 26 August 2002
Publication Date:
20 November 2002 (online)

    Permissions and Reprints All articles of this category

Abstract

Homochiral 2,2′-bis(oxazolin-2-yl)-1,1′-binaphthyl (boxax) ligands were anchored on various polymer supports including PS-PEG, PS, PEGA, and MeO-PEG via selective monofunctionalization at the 6-position of the binaphthyl backbone. Palladium(II) complexes of the supported boxax ligands catalyzed Wacker-type cyclization of 2-(2,3-dimethyl-2-butenyl)phenol to give 2-methyl-2-isopropenyl-2,3-dihydrobenzofuran with up to 96% ee.

Key words

boxax - immobilized chiral catalysts - asymmetric catalysis - Wacker-type cyclization

    References

  • For reviews, see:
  • 1a Bailey DC. Langer SH. Chem. Rev.  1981,  81:  109 
    Article in Thieme ConnectGoogle Scholar
  • 1b Shuttleworth SJ. Allin SM. Sharma PK. Synthesis  1997,  1217 
    Article in Thieme ConnectGoogle Scholar
  • 1c Burgess K. Porte AM. In Advances in Catalytic Processes   Doyle MP. JAI Press; Greenwich: 1997.  2:  p.69 
    Article in Thieme ConnectGoogle Scholar
  • 1d Shuttleworth SJ. Allin SM. Wilson RD. Nasturica D. Synthesis  2000,  1035 
    Article in Thieme ConnectGoogle Scholar
  • 1e Dörwald FZ. Organic Synthesis on Solid Phase   Wiley-VCH; Weinheim: 2000. 
    Article in Thieme ConnectGoogle Scholar
  • For studies on polymer-supported palladium catalysts reported by the author’s group, see:
  • 2a π-Allylic substitution: Uozumi Y. Danjo H. Hayashi T. Tetrahedron Lett.  1997,  38:  3557 
    CrossrefPubMedGoogle Scholar
  • 2b Asymmetric allylic substitution: Uozumi Y. Danjo H. Hayashi T. Tetrahedron Lett.  1998,  39:  8303 
    CrossrefPubMedGoogle Scholar
  • 2c π-Allylic substitution: Danjo H. Tanaka D. Hayashi T. Uozumi Y. Tetrahedron  1999,  55:  14341 
    CrossrefPubMedGoogle Scholar
  • 2d Cross-coupling: Uozumi Y. Danjo H. Hayashi T. J. Org. Chem.  1999,  64:  3384 
    CrossrefPubMedGoogle Scholar
  • 2e Carbonylation reaction: Uozumi Y. Watanabe T. J. Org. Chem.  1999,  64:  6921 
    CrossrefPubMedGoogle Scholar
  • 2f Asymmetric allylic substitution: Uozumi Y. Shibatomi K. J. Am. Chem. Soc.  2001,  123:  2919 
    CrossrefPubMedGoogle Scholar
  • 2g Cross-coupling: Uozumi Y. Nakai Y. Org. Lett.  2002,  4:  2997 
    CrossrefPubMedGoogle Scholar
  • 2h

    Sonogashira reaction: Uozumi, Y.; Kobayashi, Y. Heterocycles 2002, in press
    CrossrefPubMedGoogle Scholar
  • 3 Chiral Catalyst Immobilization and Recycling   De Vos DE. Vankelecom IFJ. Jacobs PA. Wiley-VCH; Weinheim: 2000. and references cited therein
    Google Scholar
  • 4 Uozumi Y. Kyota H. Kishi E. Kitayama K. Hayashi T. Tetrahedron: Asymmetry  1996,  7:  1603 
    CrossrefGoogle Scholar
  • 5a Uozumi Y. Kato K. Hayashi T. J. Am. Chem. Soc.  1997,  119:  5063 
    Google Scholar
  • 5b Uozumi Y. Kato K. Hayashi T. J. Org. Chem.  1998,  63:  5071 
    Google Scholar
  • 5c Uozumi Y. Kyota H. Hayashi T. J. Org. Chem.  1999,  64:  1621 
    Google Scholar
  • 6 For a recent review of solid-phase reactions using palladium catalysts, see: Uozumi Y. Hayashi T. Solid-Phase Palladium Catalysis for High-throughput Organic Synthesis, In Handbook of Combinatorial Chemistry   Nicolaou KC. Hanko R. Hartwig W. Wiley-VCH; Weinheim: 2002.  p.531-584  
    Google Scholar
  • For recent examples of the immobilization of binaphthyl-based chiral catalysts, see:
  • 7a Nozaki K. Itoi Y. Shibahara F. Shirakawa E. Ohta T. Takaya H. Hiyama T. J. Am. Chem. Soc.  1998,  120:  4051 
    CrossrefGoogle Scholar
  • 7b Nozaki K. Itoi Y. Shibahara F. Shirakawa E. Ohta T. Takaya H. Hiyama T. Bull. Chem. Soc. Jpn.  1999,  72:  1911 
    CrossrefGoogle Scholar
  • 7c Bayston DJ. Fraser JL. Ashton MR. Baxter AD. Polywka MEC. Moses E. J. Org. Chem.  1998,  63:  3137 
    CrossrefGoogle Scholar
  • 7d Kobayashi S. Kusakabe K. Ishitani H. Org. Lett.  2000,  2:  1225 
    CrossrefGoogle Scholar
  • 7e Fujii A. Sodeoka M. Tetrahedron Lett.  1999,  40:  8011 
    CrossrefGoogle Scholar
  • 7f Matsunaga S. Ohshima T. Shibasaki M. Tetrahedron Lett.  2000,  41:  8473 
    CrossrefGoogle Scholar
  • 7g Nogami H. Matsunaga S. Kanai M. Shibasaki M. Tetrahedron Lett.  2001,  42:  279 
    CrossrefGoogle Scholar
  • 7h Takamura M. Funabashi K. Kanai M. Shibasaki M. J. Am. Chem. Soc.  2001,  123:  6801 ; see also ref.
    CrossrefGoogle Scholar
  • 8a Kawashima M, and Kakayama M. inventors; Japan Patent J P  200044504.  ; assigned to Kankyo Kagaku Center K.K., Japan.
    Crossref
  • 8b De Vanis J.-BR. Tetrahedron Lett.  2001,  42:  6507 
    CrossrefGoogle Scholar
  • 9 During preparation of this manuscript, controlled mono-bromination of 1,1′-bi-2-naphthol via the monopivalate 9 was reported, see: Cai D. Larsen RD. Reider PJ. Tetrahedron Lett.  2002,  43:  4055 
    CrossrefGoogle Scholar
  • 11a Hotta H. Suzuki T. Miyano S. Inoue Y. J. Mol. Cat.  1989,  54:  L5 
    CrossrefGoogle Scholar
  • 11b Ohta T. Ito M. Inagaki K. Takaya H. Tetrahedron Lett.  1993,  34:  1615 
    CrossrefGoogle Scholar
  • 16 For a copolymerisate of acrylamidopropyl[2-amino-propyl]polyethylene glycol and N,N-dimethylacrylamide crosslinked with bis(2-acrylamidopropyl)poly(ethylene glycol) (PEGA), see: Meldal M. Tetrahedron Lett.  1992,  33:  3077 
    CrossrefGoogle Scholar
  • For reviews of PEG-supported reagents, see:
  • 18a Sieber F. Wentworth P. Janda KD. J. Comb. Chem.  1999,  1:  540 
    CrossrefGoogle Scholar
  • 18b Wentworth P. Janda KD. Chem. Commun.  1999,  1917 
    CrossrefGoogle Scholar
  • 18c Toy PH. Janda KD. Acc. Chem. Res.  2000,  33:  546 
    CrossrefGoogle Scholar
  • 19a

    Immobilization of Boxax Ligands: A typical procedure is given for the preparation of the PS-PEG resin-supported ligand 4. Boxax methyl ester 18 and LiOH·H2O (1.05 equiv to methyl ester) was stirred in a mixture of THF/H2O at 25 °C for 24 h. After removal of the solvent in vacuo a white precipitate 19 was obtained. A mixture of 19 (1.1 equiv to an amino residue of resin), HOBt (1.0 equiv) and EDCI (2.5 equiv) and PS-PEG amino resin in DMF was shaken at 25 °C for 12 h. To a reaction mixture was added EDCI (5 equiv) and the mixture was continuously shaken for an additional 24 h during which the progress of the reaction was monitored by a Kaiser test. [19b] The reaction mixture was filtered and the resin beads were rinsed with DMF, MeOH and DCM to give a polymer resin supported boxax ligand. A negative Kaiser test and 13C-MASNMR studies indicated the complete consumption of the terminal amino residue of the starting resin and the exclusive formation of the desired PS-PEG supported boxax ligands. The loading value of the polymer-supported boxax ligands 4a-d were estimated to be 0.35 mmol/g based on the initial loading value of the amino residue. 13C-MASNMR data of 4a-d: 4a: δ = 17.92, 18.25, 31.35, 32.36, 37.33, 39.01, 69.64, 72.08, 124.86, 125.39, 131.29, 132.62, 133.79, 134.04, 134.12, 137.33, 137.63, 139.31, 163.31, 171.63. 4b: δ = 31.26, 37.12, 38.94, 74.10, 131.23, 132.58, 133.97, 134.27, 137.46, 137.81, 139.70, 142.05, 164.68, 171.68. 4c: δ = 25.21, 31.34, 33.27, 37.43, 39.00, 67.74, 75.75, 124.66, 125.18, 131.39, 132.69, 133.95, 134.18, 137.74, 137.81, 138.02, 139.28, 162.75, 171.68. 4d: δ = 27.67, 31.30, 37.29, 39.00, 66.53, 78.96, 125.40, 131.17, 132.50, 133.60, 133.88, 136.54, 136.82, 139.35, 163.06, 171.59.
    CrossrefPubMed
  • 19b Kaiser E. Colescott RL. Bossinger CD. Cook PI. Anal. Biochem.  1970,  34:  595 
    CrossrefPubMedGoogle Scholar
  • For recent examples of PEG-supported binaphthyl-based chiral catalysts, see:
  • 21a Guerreiro P. Ratovelomanana-Vidal V. Genet J.-P. Dellis P. Tetrahedron Lett.  2001,  42:  3423 
    Google Scholar
  • 21b Fan Q.-H. Deng G.-J. Lin C.-C. Chan ASC. Tetrahedron: Asymmetry  2001,  12:  1241 
    Google Scholar
  • 21c Yang X.-W. Sheng J.-H. Da C S. Wang H.-S. Su W. Wang R. Chan ASC. J. Org. Chem.  2000,  65:  295 
    Google Scholar
  • 21d Fan Q.-H. Deng G.-J. Chen X.-M. Xie W.-C. Jiang D.-Z. Liu D.-S. Chan ASC. J. Mol. Cat. A.  2000,  159:  37 ; see also ref. 2b
    Google Scholar
  • For recent examples of PEG-supported chiral oxazoline ligands, see:
  • 22a Annunziata R. Benaglia M. Cinquini M. Cozzi F. Pitillo M. J. Org. Chem.  2001,  66:  3160 
    CrossrefGoogle Scholar
  • 22b Glos M. Reiser O. Org. Lett.  2000,  2:  2045 
    CrossrefGoogle Scholar
10

The enantiomeric purity of (S)-12 and (S)-14 were determined to be both >98% by HPLC analysis using chiral stationary phase column (Daicel Chiracel OD-H, eluent:
n-hexane-isopropanol = 10:1).

12

Compounds 17a-c were obtained as single diastereomers.

13

Specific rotation data of 18a-d: 18a: [α]D 25 -97.75 (c 0.75, THF). 18b: [α]D 25 -16.93 (c 0.48, THF). 18c: [α]D 25 -54.95 (c 0.58, THF). 18d: [α]D 25 -7.28 (c 0.49, THF).

14

ArgoGel amino resin (1% DVB cross-linked) purchased from Argonaut Technologies Inc. was used.

15

Aminomethylated polystyrene (1% DVB cross-linked) was purchased from Novabiochem.

17

MeO-PEG5000 amino resin was purchased from Fluka.

20

General Procedure for the Asymmetric Wacker-Type Cyclization of 1: A mixture of immobilized catalyst (0.02 mmol Pd), 2-(2,3-dimethyl-2-butenyl)-phenol(1) (0.2 mmol, 35.2 mg), benzoquinone (0.8 mmol, 86.4 mg) and MeOH (1 mL) was agitated at 60 °C with shaking for 20 h. After being cooled to r.t., the resin was filtered off and washed twice with MeOH (1 mL). The solvent was removed in vacuo and the residue was purified by column chromatography using silica gel and n-hexane-EtOAc (95:5) giving (S)-2-iso-propenyl-2-methyl-2,3-dihydrobenzofuran(2) as colorless oil. The ee was determined by GC (chiral stationary phase capillary column Cyclodex CB).