CC BY ND NC 4.0 · Synlett 2019; 30(04): 393-396
DOI: 10.1055/s-0037-1611640
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Gold-Catalyzed Cyclization/Intermolecular Methylene Transfer ­Sequence of O-Propargylic Oximes Derived from Glyoxylates

Shinya Gima
a  Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku Sendai, 980-8578, Japan
,
Keigo Shiga
a  Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku Sendai, 980-8578, Japan
,
a  Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku Sendai, 980-8578, Japan
,
b  Research and Analytical Center for Giant Molecules, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku Sendai, 980-8578, Japan   Email: itaru-n@tohoku.ac.jp
› Author Affiliations
This work was supported by JSPS KAKENHI Grant Number JP16H00996 in Precisely Designed Catalysts with Customized Scaffolding.
Further Information

Publication History

Received: 25 September 2018

Accepted after revision: 18 November 2018

Publication Date:
06 December 2018 (eFirst)

 

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

Abstract

We successfully extended our gold-catalyzed skeletal rearrangement reaction of O-propargylic oximes through C=N bond cleavage to include substrates having an ester group on the oxime moiety, affording the corresponding 2-isoxazolines having an alkoxycarbonylmethylene group at the 4-position in good to high yields. Our mechanistic studies indicated that the transfer of the alkoxycarbonylmethylene group proceeded in an intermolecular manner, confirming that the reaction proceeds through cyclization followed by intermolecular transfer of the alkoxycarbonylmethylene group.

Supporting Information

 
  • References and Notes


    • For selected reviews on gold catalysis, see:
    • 1a Li Y, Li W, Zhang J. Chem. Eur. J. 2017; 23: 467
    • 1b Harris RJ, Widenhoefer RA. Chem. Soc. Rev. 2016; 45: 4533
    • 1c Yang W, Hashmi AS. K. Chem. Soc. Rev. 2014; 43: 2941
    • 1d Obradors C, Echavarren AM. Chem. Commun. 2014; 50: 16
    • 1e Hashmi AS. K. Angew. Chem. Int. Ed. 2010; 49: 5232
    • 1f Adcock HV, Davies PW. Synthesis 2012; 44: 3401
    • 1g Bhunia S, Liu R.-S. Pure Appl. Chem. 2012; 84: 1749
    • 1h Lu B.-L, Dai L, Shi M. Chem. Soc. Rev. 2012; 41: 3318
    • 1i Kirsch SF. Synthesis 2008; 3183
    • 1j Skouta R, Li C.-J. Tetrahedron 2008; 64: 4917
    • 1k Hashmi AS. K. Chem. Rev. 2007; 107: 3180

      For pioneering works, see:
    • 2a Trost BM, Tanoury GJ. J. Am. Chem. Soc. 1988; 110: 1636
    • 2b Chatani N, Morimoto T, Muto T, Murai S. J. Am. Chem. Soc. 1994; 116: 6049

    • For reviews, see:
    • 2c Wang Q, Shi M. Synlett 2017; 28: 2230
    • 2d Dorel R, Echavarren AM. J. Org. Chem. 2015; 80: 7321
    • 2e Michelet V. Top. Curr. Chem. 2015; 357: 95

      For pioneering works, see:
    • 3a Rautenstrauch V. J. Org. Chem. 1984; 49: 950
    • 3b Mainetti E, Mouriès V, Fensterbank L, Malacria M, Marco-Contelles J. Angew. Chem. Int. Ed. 2002; 41: 2132

    • For reviews, see:
    • 3c Boyle JW, Zhao Y, Chan PW. H. Synthesis 2018; 50: 1402
    • 3d Fensterbank L, Malacria M. Acc. Chem. Res. 2014; 47: 953
    • 3e Mauleon P, Toste FD. In Modern Gold Catalyzed Synthesis . Chap. 4, Hashmi SK, Toste FD. Wiley-VCH; Weinheim: 2012: 75
    • 4a Nakamura I, Gima S, Kudo Y, Terada M. Angew. Chem. Int. Ed. 2015; 54: 7154
    • 4b Gima S, Nakamura I, Terada M. Eur. J. Org. Chem. 2017; 4375
  • 5 Identifiable byproducts were not obtained from the reaction of (Z)-1a. It is therefore unclear at the present stage why the reaction of (Z)-1a resulted in a low chemical yield.
  • 6 Ethyl (2Z)-(3,5-Diphenylisoxazol-4(5H)-ylidene)acetate [(Z)-2a]; Typical ProcedureOxime (E)-1a (61.5 mg, 0.2 mmol) in CH2Cl2 (0.4 mL) was added to (4-F3CC6H4)3PAuNTf2 (18.9 mg, 0.02 mmol) in a V-vial under argon, and the mixture was stirred at 30 °C for 2 h. The mixture was then passed through a short pad of silica gel, eluting with CH2Cl2 (50 mL). The solvents were evaporated in vacuo, and the crude product was purified by flash column chromatography [silica gel, hexane–EtOAc (8:1)] to give a colorless liquid; yield: 50 mg (81%, Z/E = 90:10). IR (neat): 3063, 3033, 2981, 2939, 2903, 1709, 1641, 1494, 1455, 1444, 1367, 1331, 1310, 1299, 1269, 1199, 1130, 1096, 1077, 1035, 1007, 912, 899, 873 cm–1. 1H NMR (400 MHz, CDCl3): δ = 7.67–7.62 (m, 2 H), 7.55–7.50 (m, 3 H), 7.39–7.31 (m, 5 H), 6.76 (d, J = 3.2 Hz, 1 H), 6.32 (d, J = 3.2 Hz, 1 H), 4.06 (q, J = 7.3 Hz, 2 H), 1.14 (t, J = 7.3 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 165.22, 157.47, 155.10, 137.69, 130.36, 129.07, 128.70, 128.63, 128.33, 127.58, 127.39, 115.57, 88.03, 60.83, 14.01. HRMS (ESI): m/z [M + Na]+ calcd for C19H17NNaO3: 330.1101; found: 330.1100.
  • 7 A substrate having a trichloromethyl group was not converted into the desired product under the optimal reaction conditions; 60% of the starting material was recovered. Preparations from substrates having a cyano or keto group instead of an ester group failed.
  • 8 The reaction of 1i at 50 °C afforded the desired product 2i in 12% yield.
    • 9a Dunn PJ, Graham AB, Grigg R, Higginson P, Sridharan V, Thornton-Pett M. Chem. Commun. 2001; 1968
    • 9b Broggini G, Bruché L, Zecchi G, Pilati T. J. Chem. Soc., Perkin Trans. 1 1990; 533