Synthesis 2016; 48(23): 4072-4080
DOI: 10.1055/s-0035-1562482
paper
© Georg Thieme Verlag Stuttgart · New York

A General and Robust Method for the Preparation of (E)- and (Z)-Stereodefined Fully Substituted Enol Tosylates: Promising Cross-Coupling Partners

Yuichiro Ashida
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
,
Yuka Sato
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
,
Atsushi Honda
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
,
Hidefumi Nakatsuji*
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
,
Yoo Tanabe*
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
› Author Affiliations
Further Information

Publication History

Received: 10 May 2016

Accepted after revision: 04 July 2016

Publication Date:
15 August 2016 (eFirst)

Abstract

A robust method for preparing (E)- and (Z)-stereodefined fully substituted enol tosylates is described. α-Substituted β-keto esters undergo (E)-selective enol tosylations using TsCl–Me2N(CH2)6NMe2 as the reagent (method A, 13 examples; 63–96%) and (Z)-selective enol tosylations using TsCl–TMEDA–LiCl as the reagent (method B, 13 examples; 62–99%). A plausible mechanism for the (E)- and (Z)-enol tosylation selectivity is proposed. A 1H NMR monitoring experiment revealed that TsCl coupled with TMEDA formed a simple N-sulfonylammonium intermediate.

Supporting Information

 
  • References

    • 2a Baxter JM, Steinhuebel D, Palucki M, Davies IW. Org. Lett. 2005; 7: 215
    • 2b Steinhuebel D, Baxter JM, Palucki M, Davies IW. J. Org. Chem. 2005; 70: 10124
    • 2c Klapars A, Campos KR, Chen CY, Volante RP. Org. Lett. 2005; 7: 1185
    • 2d Molinaro C, Scott JP, Shevlin M, Wise C, Menard A, Gibb A, Junker EM, Lieberman D. J. Am. Chem. Soc. 2015; 137: 999

      For selected examples, see:
    • 3a Tanabe Y, Yamamoto H, Yoshida Y, Miyawaki T, Utsumi N. Bull. Chem. Soc. Jpn. 1995; 68: 297
    • 3b Yoshida Y, Sakakura Y, Aso N, Okada S, Tanabe Y. Tetrahedron 1999; 55: 2183
    • 3c Yoshida Y, Shimonishi K, Sakakura Y, Okada S, Aso N, Tanabe Y. Synthesis 1999; 1633
    • 3d Morita J, Nakatsuji H, Misaki T, Tanabe Y. Green Chem. 2005; 7: 711

      For selected examples, see:
    • 4a Tanabe Y, Murakami M, Kitaichi K, Yoshida Y. Tetrahedron Lett. 1994; 35: 8409
    • 4b Tanabe Y, Okumura H, Maeda A, Murakami M. Tetrahedron Lett. 1994; 35: 8413
    • 4c Iida A, Horii A, Misaki T, Tanabe Y. Synthesis 2005; 2677
    • 4d Tanabe Y, Misaki T, Kurihara M, Iida A. Chem. Commun. 2002; 1628
    • 4e Iida A, Okazaki H, Misaki T, Sunagawa M, Sasaki A, Tanabe Y. J. Org. Chem. 2006; 71: 5380
    • 4f Iida A, Hashimoto C, Misaki T, Katsumoto Y, Ozaki Y, Tanabe Y. J. Org. Chem. 2007; 72: 4970
    • 4g Okabayashi T, Iida A, Takai K, Nawate Y, Misaki T, Tanabe Y. J. Org. Chem. 2007; 72: 8142
    • 4h Takai K, Nawate Y, Okabayashi T, Nakatsuji H, Iida A, Tanabe Y. Tetrahedron 2009; 65: 5596
    • 5a Nakatsuji H, Ueno K, Misaki T, Tanabe Y. Org. Lett. 2008; 10: 2131
    • 5b Nakatsuji H, Nishikado H, Ueno K, Tanabe Y. Org. Lett. 2009; 11: 4258
    • 5c Nishikado H, Nakatsuji H, Ueno K, Nagase R, Tanabe Y. Synlett 2010; 2078
    • 5d Ashida Y, Sato Y, Suzuki T, Ueno K, Kai K, Nakatsuji H, Tanabe Y. Chem. Eur. J. 2015; 21: 5934
    • 6a Manabe A, Ohfune Y, Shinada T. Synlett 2012; 23: 1213
    • 6b Totsuka Y, Ueda S, Kuzuyama T, Shinada T. Bull. Chem. Soc. Jpn. 2015; 88: 575
    • 6c Li H, Mazet C. J. Am. Chem. Soc. 2015; 137: 10720
    • 6d Yanagita Y, Suto T, Matsuo N, Kurosu Y, Sato T, Chida N. Org. Lett. 2015; 17: 1946
  • 7 Christensen M, Nolting A, Shevlin M, Weisel M, Maligres PE, Lee J, Orr RK, Plummer CW, Tudge MT, Campeau LC, Ruck RT. J. Org. Chem. 2016; 81: 824
  • 8 Nakatsuji H, Ashida Y, Hori H, Sato Y, Honda A, Taira M, Tanabe Y. Org. Biomol. Chem. 2015; 13: 8205
  • 9 The use of LiCl instead of LiOH was also applied by Shinada’s group; see refs. 6a and 6b.
  • 10 The 50 gram-scale preparation of 1a was performed by the self Ti-Claisen condensation using methyl hexanoate with TiCl4 and Et3N at 0–5 °C for 1 h (93% yield); see the Supporting Information and ref. 8.
  • 11 TMEDA: ca. $80/500 g; Me2N(CH2)3NMe2: ca. $110/500 g; Me2N(CH2)6NMe2: ca. $90/500 g. Reagent base.
  • 12 After finishing this work, EtOAc and toluene were available for reactive not fully, trisubstituted substrates.
  • 13 This issue is addressed in ref. 2a. To solve the problem, presumably, the Merck group consistently uses reactive but highly expensive Ts2O instead of TsCl.
  • 14 This monitoring study resembles the case of TsCl–NMI (see refs. 5a and 5d) and (PhO)2POCl–NMI (see ref. 8) intermediates.
  • 15 A related monitoring experiment using p-MeC6H4COCl with TMEDA was carried out in our hands; noticeable changes of 1H NMR spectra were not observed under the identical conditions. The interactive action of TsCl, therefore, may be stronger than that of benzoyl chlorides.

    • Oriyama’s group reported pioneering work on chiral-diamine-catalyzed desymmetric benzoylations of meso-diols with PhCOCl and speculation regarding the mechanism. Contrary to the present result, they proposed the corresponding N,N′-chelate-type intermediate; see
    • 16a Sano T, Oriyama T. J. Synth. Org. Chem. Jpn. 1999; 57: 598
    • 16b Oriyama T, Imai K, Sano T, Hosoya T. Tetrahedron Lett. 1998; 57: 598
    • 16c Sano T, Miyata H, Oriyama T. Enantiomer 2000; 5: 119
    • 16d Terakado D, Oriyama T. Org. Synth. 2006; 83: 70