Synlett 2014; 25(19): 2738-2742
DOI: 10.1055/s-0034-1379219
© Georg Thieme Verlag Stuttgart · New York

Nitrate-Enhanced NHC-NiH Catalyzed Tail-to-Tail Vinyl Ether Dimerization

Lisi He
a  Department of Chemistry, Shenzhen Research Institute, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong   Email:
Chun-Yu Ho*
a  Department of Chemistry, Shenzhen Research Institute, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong   Email:
b  Department of Chemistry, South University of Science and Technology of China (SUSTC), Shenzhen 518055, P. R. of China   Email:
› Author Affiliations
Further Information

Publication History

Received: 23 July 2014

Accepted after revision: 07 September 2014

Publication Date:
07 October 2014 (online)


The first tail-to-tail vinyl ether dimerization has been developed by using a newly identified synergistic effect between the NHC-NiH catalyst and organonitrate additive (PhNO2 or t-BuNO2). The additive enhanced the desired C–C bond-forming reactivity by a proposed competitive coordination with the alkoxyl group of the hydrometallated vinyl ether species to the Ni center. This combination addressed complications related to β-alkoxy (β-OR) elimination and polymerization, and gave unexpected dimerization regioselectivity.

Supporting Information

  • References and Notes

    • For reviews, see:
    • 2a Goethals EJ, Du Prez F. Prog. Polym. Sci. 2007; 32: 220
    • 2b Aoshima S, Kanaoka S. Chem. Rev. 2009; 109: 5245
    • 3a Kojima K, Sawamoto M, Higashimura T. Macromolecules 1989; 22: 1552
    • 3b Andersson H, Gedde UW, Hult A. Macromolecules 1996; 29: 1649
    • 3c Lee J.-Y, Kim M.-J, Jin M.-K, Ahn M.-R. Bull. Korean Chem. Soc. 1999; 20: 1355
    • 4a Goethals EJ, Reyntjens W, Zhang X, Verdonck B, Loontjens T. Macromol. Symp. 2000; 157: 93
    • 4b Bernaerts KV, Du Prez FE. Polymer 2005; 46: 8469
    • 4c Radchenko AV, Kostjuk SV, Ganachaud F. Polym. Chem. 2013; 4: 1883
    • 5a Kim JJ, Alper H. Chem. Commun. 2005; 3059
    • 5b Gopal D, Rajagopalan K. Tetrahedron Lett. 1987; 28: 5327
    • 5c Wei X, Lorenz JC, Kapadia S, Saha A, Haddad N, Busacca CA, Senanayake CH. J. Org. Chem. 2007; 72: 4250
    • 5d Shigemitsu Y, Katsuhara Y, Odaira Y. Tetrahedron Lett. 1971; 2887
    • 5e Esquivias J, Gómez Arrayás R, Carretero JC. J. Am. Chem. Soc. 2007; 129: 1480
    • 6a Terada Y, Arisawa M, Nishida A. Angew. Chem. Int. Ed. 2004; 43: 4063
    • 6b Klet RC, Labinger JA, Bercaw JE. Organometallics 2012; 31: 6652
    • 6c Liu S, Berry N, Thomson N, Pettman A, Hyder Z, Mo J, Xiao J. J. Org. Chem. 2006; 71: 7467
    • 7a Aoyama H, Tokunaga M, Hiraiwa S, Shirogane Y, Obora Y, Tsuji Y. Org. Lett. 2004; 6: 509
    • 7b Aoyama H, Tokunaga M, Kiyosu J, Iwasawa T, Obora Y, Tsuji Y. J. Am. Chem. Soc. 2005; 127: 10474
    • 9a Watanabe WH, Conlon LE. J. Am. Chem. Soc. 1957; 79: 2828
    • 9b McKeon JE, Fitton P, Griswold AA. Tetrahedron 1972; 28: 227
    • 9c Handerson S, Schraf M. Org. Lett. 2002; 4: 407
    • 9d Bosch M, Schraf M. J. Org. Chem. 2003; 68: 5225
    • 9e Okimoto Y, Sakaguchi S, Ishii Y. J. Am. Chem. Soc. 2002; 124: 1590
    • 9f Nakagawa H, Okimoto Y, Sakaguchi S, Ishii Y. Tetrahedron Lett. 2003; 44: 103
    • 9g Nakamura A, Tokunaga M. Tetrahedron Lett. 2008; 49: 3729

      For early-transition-metal-catalyzed dimerization reactions, see:
    • 10a Christoffers J, Bergman RG. J. Am. Chem. Soc. 1996; 118: 4715
    • 10b Janiak C. Coord. Chem. Rev. 2006; 250: 66

      For recent reviews on hydrovinylation by others and by us, see:
    • 11a RajanBabu TV. Chem. Rev. 2003; 103: 1845
    • 11b Hilt G, Weske DF. Chem. Soc. Rev. 2009; 38: 3082
    • 11c RajanBabu TV. Synlett 2009; 853
    • 11d Ho C.-Y, He L, Chan C.-W. Synlett 2011; 1649
    • 11e Ceder RM, Grabulosa A, Muller G, Rocamora M. Catal. Sci. Technol. 2013; 3: 1446

      We could not isolate the hydride catalyst generated in situ for characterization. Nevertheless, treatment of [(allyl)(IPr)NiCl] with AgOTf provided similar catalytic activity with the tentatively assigned hydride catalyst in the following publications:
    • 12a Ho C.-Y, He L. Angew. Chem. Int. Ed. 2010; 49: 9182
    • 12b Ho C.-Y, He L. Chem. Commun. 2012; 48: 1481
    • 12c Ho C.-Y, He L. J. Org. Chem. 2014; DOI: 10.1021/jo5008477

      For other recent representative examples, see:
    • 13a Page JP, RajanBabu TV. J. Am. Chem. Soc. 2012; 134: 6556
    • 13b Park J.-W, Park SJ, Jun C.-H. Org. Lett. 2012; 14: 1468
    • 13c Kato T, Matsuoka S, Suzuki M. J. Org. Chem. 2014; 79: 4484

      For Pd-catalyzed polymerization of vinyl ethers, see:
    • 14a Luo S, Jordan RF. J. Am. Chem. Soc. 2006; 128: 12072
    • 14b Chen C, Luo S, Jordan RF. J. Am. Chem. Soc. 2010; 132: 5273
    • 14c Chen C, Luo S, Jordan RF. J. Am. Chem. Soc. 2008; 130: 12892
  • 15 See ref. 11c; polymerization obtained with the use of [Ph3P(allyl)Ni(OTf)].
  • 16 For the dimerization of vinyl ethers to α,γ-unsaturated acetals, see: Chen C, Jordan RF. J. Am. Chem. Soc. 2010; 132: 10254
  • 17 [NHC–NiH(OTf)] Catalyst Generation: In a glove box, Ni(cod)2 (0.05 mmol) and IPr, SIPr, or IMes (0.05 mmol) were added to an oven-dried test tube equipped with a stir bar. After sealing with a septum, the tube was brought out of the glove box and connected to an N2 line. The mixture was dissolved in dried degassed toluene (2 mL, or indicated amount) and stirred at r.t. for 1 h. 1-Octene (0.2 mmol), Et3N (0.3 mmol), p-anisaldehyde (0.05 mmol), and TESOTf (0.1 mmol) were then added sequentially and the mixture was stirred at r.t. for 45 min. Catalytic Tail-to-Tail Vinyl Ether Dimerization by [IPr-NiH(OTf)] and PhNO2; General Procedure: Catalyst (0.05 mmol) was generated according to the above general procedure except that only 0.5 mL toluene was used. PhNO2 (1.5 mL) was then added to the above directly before adding vinyl ether (1.0 mmol for 5 mol% reactions or 2.0 mmol for 2.5 mol% reactions). After stirring at r.t. for 24 h, a spatula of Na2CO3 (s) was added and the mixture was diluted with hexane (4 mL), and stirred in open air for 30 min. The mixture was then filtered through a short plug of silica gel and rinsed with diethyl ether (75 mL). The solvent was removed under vacuum and the reside was purified by silica gel column chromatography (hexane–CH2Cl2 5:1, 4:1, 3:1, 2:1, then 1:1, all with 1% Et3N buffer) to give the dimers as colorless oils. When the vinyl ether dimers had boiling points similar to that of PhNO2, the pure vinyl ether dimers for characterization were obtained by using t-BuNO2 as additive.
  • 18 The polymerization was also detected by 1H NMR spectroscopic analysis and found to be comparable1–4 with those previously reported.

    • According to Jones, the relative donor strength based on competitive displacement studies is: CH3NO2 < C6H5NO2 < Et2O < DMF, see:
    • 19a Jones DE. H, Wood JL. J. Chem. Soc. A 1971; 3132
    • 19b Jones DE. H, Wood JL. J. Chem. Soc. A 1971; 3135
  • 20 For an example of using RNO2 in polymerization, see: Huckfeldt JT. G, Risse W. Macromol. Chem. Phys. 1998; 199: 861
  • 21 This might be due to catalyst deactivation or decomposition in the presence of those nitroalkanes. It was suggested by a control experiment: After adding 0.5 mL MeNO2 to the cross-hydroalkenylation system reported in ref. 12a, no substrate conversion was observed.