Synlett 2017; 28(18): 2483-2488
DOI: 10.1055/s-0036-1589080
letter
© Georg Thieme Verlag Stuttgart · New York

Chiral Phosphinyl Enamines and Their Asymmetric Reduction through Group-Assisted Purification Chemistry Leading to Enantiopure β-Amino Esters/Amides

Shuo Qiaoa, Jianbin Wua, b, Junming Moa, Preston T. Spigenera, Brian Nlong Zhaoc, Bo Jiang*a, d, Guigen Li*a, b
  • aDepartment of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA   Email: guigen.li@ttu.edu
  • bInstitute of Chemistry and Biomedical Sciences (ICBMS), Nanjing University, Nanjing 210093, P. R. of China
  • cShanghai High School International Division, No. 989, Baise Road, Shanghai 200231, P. R. of China
  • dSchool of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, P. R. China   Email: jiangchem@jsnu.edu.cn
We would like to acknowledge financial support from the National Natural Science Foundation of China (No. 21332005, 21672100) and the Robert Welch Foundation (D-1306).
Further Information

Publication History

Received: 11 May 2017

Accepted after revision: 26 June 2017

Publication Date:
04 August 2017 (eFirst)

Abstract

A series of new chiral N-phosphinyl β-enamino esters and amides were successfully prepared with excellent Z-stereoselectivity (Z/E > 99:1 in nearly all cases). Group-assisted purification chemistry proved to be an efficient method for the asymmetric reduction of the resulting β-enamino esters/amides to give enantiopure β-amino esters/amides. The asymmetric reduction can be controlled efficiently by using a combination of sodium cyanoborohydride and acetic acid.

Supporting Information

 
  • References and Notes

    • 1a An G. Seifert C. Li G. Org. Biomol. Chem. 2015; 13: 1600
    • 1b Zhang HW. Bing Y. Yang Z. Lu H. Li G. J. Org. Chem. 2016; 81: 7654
    • 1c Seifert C. Pindi S. Li G. J. Org. Chem. 2015; 80: 447
  • 2 Wu J. An G. Lin S. Xie J. Zhou W. Sun H. Pan Y. Li G. Chem. Commun. 2014; 50: 1259
  • 3 Kaur P. Pindi S. Wever W. Rajale T. Li G. J. Org. Chem. 2010; 75: 5144
  • 4 Pindi S. Kaur P. Shakya G. Li G. Chem. Biol. Drug Des. 2011; 77: 20
    • 5a Yang B. Ji X. Xue Y. Zhang H. Shen M. Jiang B. Li G. Org. Biomol. Chem. 2016; 14: 6024
    • 5b Yang B. Shen M. Ji X. Xu Z. Sun H. Jiang B. Li G. J. Org. Chem. 2016; 81: 2488
  • 6 Kattamuri PV. Ai T. Pindi S. Sun Y. Gu P. Shi M. Li G. J. Org. Chem. 2011; 76: 2792
    • 7a Wang H. Liu X. Feng X. Huang Z. Shi D. Green Chem. 2013; 15: 3307
    • 7b Chennapuram M. Emmadi NR. Bingi C. Nanubolu JB. Atmakur K. Green Chem. 2014; 16: 3237
    • 8a Abdel-Magid AF. Cohen JH. Maryanoff CA. Curr. Med. Chem. 1999; 6: 955
    • 8b Li G. Kim SH. Wei H.-X. Tetrahedron Lett. 2000; 41: 8699
    • 8c Chen DJ. Timmons C. Chao C. Li G. Eur. J. Org. Chem. 2004; 3097
    • 8d Chen DJ. Timmons C. Wei H.-X. Li G. J. Org. Chem. 2003; 68: 5742
    • 9a Davies SG. Dordor-Hedgecoch IM. Jones RH. Prout K. Tetrahedron 1986; 42: 5123
    • 9b Liebeskind LS. Welker ME. Fengl RW. J. Am. Chem. Soc. 1986; 108: 6328
  • 10 Hecht SM. Acc. Chem. Res. 1986; 19: 383
  • 11 Seebach D. Matthews JL. Chem. Commun. 1997; 2015
  • 12 Amézquita-Valencia M. Cabrera A. J. Organomet. Chem. 2014; 768: 145
    • 13a Hsiao Y. Rivera NR. Rosner T. Krska SW. Njolito E. Wang F. Sun Y. Armstrong III JD. Grabowski EJ. J. Tillyer RD. Spindler F. Malan C. J. Am. Chem. Soc. 2004; 126: 9918
    • 13b Zhang YJ. Park JH. Lee S.-g. Tetrahedron: Asymmetry 2004; 15: 2209
    • 13c Dai Q. Yang W. Zhang X. Org. Lett. 2005; 7: 5343
    • 13d Blot J. Bardou A. Bellec C. Fargeau-Bellassoued M.-C. Célérier JP. Lhommet G. Gardette D. Gramain J.-C. Tetrahedron Lett. 1997; 38: 8511
    • 14a Enders D. Wahl H. Bettray W. Angew. Chem. Int. Ed. Engl. 1995; 34: 455
    • 14b Zhou Y.-G. Tang W. Wang W.-B. Li W. Zhang X. J. Am. Chem. Soc. 2002; 124: 4952
    • 15a You J. Drexler H.-J. Zhang S. Fischer C. Heller D. Angew. Chem. Int. Ed. 2003; 42: 913
    • 15b Tang W. Wu S. Zhang X. J. Am. Chem. Soc. 2003; 125: 9570
    • 15c Zhu G. Chen Z. Zhang X. J. Org. Chem. 1999; 64: 6907
    • 15d Peña D. Minnaard AJ. de Vries JG. Feringa BL. J. Am. Chem. Soc. 2002; 124: 14552
    • 15e Wu J. Chen X. Guo R. Yeung C. Chan AS. C. J. Org. Chem. 2003; 68: 2490
  • 16 Han JL. Ai T. Li G. Synthesis 2008; 2519
  • 17 Xiong Y. Mei H. Wu L. Han J. Pan Y. Li G. Beilstein J. Org. Chem. 2014; 10: 653
    • 18a Inbar Feske M. Buitrago Santanilla A. Leighton JL. Org. Lett. 2010; 12: 688
    • 18b Pool B. Balalaie S. Kunze A. Schilling G. Bischof P. Gleiter R. Eur. J. Org. Chem. 2004; 2812
  • 19 Bartoli G. Cimarelli C. Marcantoni E. Palmieri G. Petrini M. J. Org. Chem. 1994; 59: 5328
  • 20 CCDC 1448298 contains the supplementary crystallographic data for compound 3e. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/getstructures.
  • 21 Xie J.-b. Luo J. Winn TR. Cordes DB. Li G. Beilstein J. Org. Chem. 2014; 10: 746
  • 22 Koszelewski D. Lavandera I. Clay D. Guebitz GM. Rozzell D. Kroutil W. Angew. Chem. Int. Ed. 2008; 47: 9337
  • 23 Phosphinyl Enamines 2; General Procedure A mixture of phosphinamide P3 (200 mg, 0.74 mmol) , β-keto ester 1 (2.21mmol), 4 Å MS (50 mg), and TsOH (5.0 mg) in toluene (3.0 ml) was heated in a sealed vial for 10 h at 100 °C until the limiting reactant was consumed (TLC). The mixture was then filtered, diluted with EtOAc (5 mL), washed with sat. aq NaHCO3 and brine, and evaporated to dryness. The residue was purified by flash chromatography [silica gel, EtOAc–hexane (1:3)]. The eluting solvents were combined and evaporated under vacuum to afford the phosphinyl enamide as a yellow oil. All new compounds were characterized by spectroscopy (31P, 1H, and 13C NMR). Ethyl (2Z)-3-{[(2S,5S)-1-Oxido-2,5-diphenylphospholan-1-yl]amino}but-2-enoate (2c) Yellow oil; yield: 277 mg (98%). 1H NMR (400 MHz, CDCl3): δ = 9.78 (d, J = 16.2 Hz, 1 H), 7.37–7.25 (m, 10 H), 4.59 (s, 1 H), 4.14 (q, J = 5.7 Hz, 2 H), 3.68–3.58 (m, 1 H), 3.18–3.12 (m, 1 H), 2.51–2.32 (m, 2 H), 2.16–2.08 (m, 2 H), 1.42–1.39 (m, 3 H), 1.27 (t, J = 5 Hz, 3 H). 31P NMR (162 MHz, CDCl3): δ = 51.8. Ethyl (3S)-3-{[(2S,5S)-1-Oxido-2,5-diphenylphospholan-1-yl]amino}butanoate White solid; yield: 88 mg (76%); mp 186–198 °C , [α]25 D –55.2 (c 0.36, CH2Cl2); 1H NMR (400 MHz, CDCl3): δ = 7.44–7.08 (m, 10 H), 4.01–3.92 (m, 2 H), 3.52–3.50 (m, 1 H), 3.37–3.29 (m, 1 H), 3.06–2.95 (m, 1 H), 2.65 (t, J = 11 Hz, 1 H), 2.36–2.28 (m, 2 H), 2.55–2.42 (m, 2 H), 2.14–2.39 (m, 1 H), 2.08–2.02 (m, 1 H), 1.20 (t, J = 6.0 Hz, 3 H), 0.70 (t, J = 3.0 Hz, 3 H). 31P NMR (162 MHz, CDCl3): δ = 53.4; HRMS (TOF-ES+): m/z [M + H]+ calcd for C22H29NO3P: 386.1880; found: 386.1879.