Zn(ClO₄)₂·6H₂O as a Powerful Catalyst for the Conversion of β-Ketoesters into β-Enamino Esters

Abstract

Zn(ClO₄)₂·6H₂O proved to be a very powerful catalyst for the condensation of primary and secondary amines with β-ketoesters to give N-substituted β-enaminoesters.

amino acid derivatives - zinc perchlorate - condensation - amines - keto esters

References

1a Tomioka K. Ando K. Takemasa Y. Koga K. J. Am. Chem. Soc.  1984,  106:  2718 

1b Georg GI. Guan X. Kant J. Tetrahedron Lett.  1988,  29:  403 

1c Felice E. Fioravanti S. Pellacani L. Tardella PA. Tetrahedron Lett.  1999,  40:  4413 

2a Lubell WD. Kitamura M. Noyori R. Tetrahedron: Asymmetry  1991,  2:  543 

2b Bartoli G. Cimarelli C. Marcantoni E. Palmieri G. Petrini M. J. Org. Chem.  1994,  59:  5328 

2c Palmieri G. Cimarelli C. J. Org. Chem.  1996,  61:  5557 

2d Potin D. Dumas F. d’Angelo J. J. Am. Chem. Soc.  1990,  112:  3483 

2e Cimarelli C. Palmieri G. Volpini E. Synth. Commun.  2001,  31:  2943 

3a Paulvannan K. Stille JR. J. Org. Chem.  1994,  59:  1613 

3b Barta NS. Brode A. Stille JR. J. Am. Chem. Soc.  1994,  116:  6201 

3c Cook GR. Beholz LG. Stille JR. J. Org.Chem.  1994,  59:  3575 

3d Hong CY. Kishi Y. J. Am. Chem. Soc.  1992,  114:  7001 

3e Blot J. Bardou A. Bellec C. Fargeau-Bellassoued M.-C. Célérier JP. Lhommet G. Gardette D. Gramain J.-C. Tetrahedron Lett.  1997,  38:  8511 

3f Michael JP. de Koning CB. Gravestock D. Hosken GD. Howard AS. Jungmann CM. Krause RWM. Parsons AS. Pelly SC. Stanbury TV. Pure Appl. Chem.  1999,  71:  979 

3g Hernandez A. Marcos M. Rapoport H. J. Org. Chem.  1995,  60:  2683 

3h David O. Blot J. Bellec C. Fargeau-Bellassoued M.-C. Haviari G. Célérier JP. Lhommet G. Gramain J.-C. Gardette D. J. Org. Chem.  1999,  64:  3122 

3i Michael JP. Parsons AS. Tetrahedron  1999,  55:  10915 

4 Beholz LG. Benovsky P. Ward DL. Barta NS. Stille JR. J. Org. Chem.  1997,  62:  1033 

5a Elassar A.-ZA. El-Khair AA. Tetrahedron  2003,  59:  8463 

5b Agami C. Dechoux L. Hebbe S. Tetrahedron Lett.  2002,  43:  2521 

5c Stefani HA. de Avila E. Synth. Commun.  2002,  32:  2041 

5d Ferraz HMC. Pereira FLC. Leite FS. Nunes MRS. Payret-Arrua ME. Tetrahedron  1999,  55:  10915 

5e Trautwein AW. Jung G. Tetrahedron Lett.  1998,  39:  8263 

5f Erian AW. J. Prakt. Chem.  1999,  341:  147 

5g Daley V. d’Angelo J. Cavé C. Mahuteau J. Chiaroni A. Riche C. Tetrahedron Lett.  1999,  40:  1657 

5h d’Angelo J. Cavé C. Desmaele D. Gassama A. Thominiaux C. Riche C. Heterocycles  1998,  47:  725 

6a Hannick SM. Kishi Y. J. Org. Chem.  1983,  48:  3833 

6b Lee AS.-Y. Cheng R.-Y. Tetrahedron Lett.  1997,  38:  443 

6c Bird TGC. Olivier A. Bioorg. Med. Chem. Lett.  1996,  6:  515 

7a Fukuyama T. Yung YM. Tetrahedron Lett.  1981,  22:  3760 

7b Jiang N. Qu Z. Wang J. Org. Lett.  2001,  3:  2989 

8a Uneyama K. Morimoto O. Yamashita F. Tetrahedron Lett.  1989,  30:  4821 

8b Fustero S. Pina B. Simón-Fuentes A. Tetrahedron Lett.  1997,  38:  6771 

8c Fustero S. Pina B. Salavert E. Navarro A. Ramirez de Arellano MC. Simón-Fuentes A. J. Org. Chem.  2002,  67:  4667 

8d Fustero S. Pina B. García de la Torre M. Navarro A. Ramirez de Arellano MC. Simón A. Org. Lett.  1999,  1:  977 

9a Bartoli G. Cimarelli C. Dalpozzo R. Palmieri G. Tetrahedron  1995,  51:  8613 

9b Katritzky AR. Fang Y. Donkor A. Xu J. Synthesis  2000,  2029 

10 Fustero S. García del la Torre M. Jofrè V. Pérez Carlon R. Navarro A. Simón Fuentes A. J. Org. Chem.  1998,  63:  8825 

11a Ferraz HMC. Oliveira EO. Payret-Arrua ME. Brandt CA. J. Org. Chem.  1995,  60:  7357 

11b Kloek JA. Leschinsky KL. J. Org. Chem.  1978,  43:  1460 

11c Soloshonok VA. Kukhar V. Tetrahedron  1996,  52:  6953 

11d Leflemme N. Dallemagne P. Rault S. Synthesis  2002,  1740 

11e Calvet S. David O. Vanucci-Bacqué Fargeau-Bellassoued M.-C. Lhommet G. Tetrahedron  2003,  59:  6333 

12 Bartoli G. Bosco M. Marcantoni E. Massaccesi M. Rinaldi S. Sambri L. Tetrahedron Lett.  2002,  34:  6331 

13 Bartoli G. Bosco M. Dalpozzo R. Marcantoni E. Massaccesi M. Rinaldi S. Sambri L. Synlett  2003,  39 

14a Schumacher JC. Perchlorates - their Properties, Manufacture and Uses   ACS Monograph Series, Reinhold; New York: 1960. 

14b Long J. Chem. Health Saf.  2002,  9:  12 

15 Bartoli G. Bosco M. Dalpozzo R. Marcantoni E. Massaccesi M. Sambri L. Eur. J. Org. Chem.  2003,  6:  4611 

16

These conditions are sufficient to reactivate the catalyst, without any decomposition process. Zn(ClO₄)₂·6H₂O in fact decomposes under vacuum at temperatures higher than 140 °C.

17

Representative Experimental Procedure: Synthesis of tert-butyl-3-anilino-2-butenoate (1a). To a round-bottom flask Zn(ClO₄)₂·6H₂O (24 mg, 0.063 mmol), MgSO₄ (46 mg, 0.38 mmol), t-butyl acetoacetate (0.21 mL, 1.26 mmol), CH₂Cl₂ (0.5 mL) and aniline (0.17 mL, 1.90 mmol) were added. The reaction mixture was stirred at r.t. for 21 h. After addition of 5 mL of CH₂Cl₂, the catalyst was filtered off and the solution was concentrated at reduced pressure. The crude product was purified by filtration on a short silica gel column pre-treated with Et₃N. The filtered catalyst was reactivated by heating in a oven at 60 °C overnight and reused. Compounds 5a, 5b and 5e are commercial products. 1f, [21] 1h, [21] 1o, [22] 5c [23] and 5d [19] are known compounds. Spectroscopic data for selected examples follow.
t -Butyl ( Z )-3-anilino-2-butenoate ( 1a): ¹H NMR (300 MHz, CDCl₃): δ = 1.50 (s, 9 H, 3 × CH₃), 1.97 (s, 3 H, CH₃), 4.60 (bs, 1 H, CH), 7.05-7.20 (m, 3 H, Ph), 7.25-7.35 (m, 2 H, Ph), 10.40 (bs, 1 H, NH). ¹³C NMR (75 MHz, CDCl₃):
δ = 20.2 (CH₃), 28.6 (CH₃), 78.5 (C), 87.8 (CH), 124.2 (CH), 124.6 (CH), 128.9 (CH), 139.5 (C), 158.0 (C), 170.3 (C). IR (nujol): ν_NH = 3272 cm^-1. MS (EI): m/z (%) = 233(6) [M⁺], 17 7(16), 118 (41), 77 (30), 59 (100).
Ethyl ( Z )-2-(butylamino)-1-cyclopentene-1-carboxylate ( 1g): ¹H NMR (300 MHz, CDCl₃): δ = 0.93 (t, 3 H, CH₃, J _HH = 7.2 Hz), 1.27 (t, 3 H, CH₃, J _HH = 7.2 Hz), 1.35-1.40 (m, 2 H, CH₂), 1.45-1.60 (m, 2 H, CH₂), 1.80-1.90 (m, 2 H, CH₂), 2.45-2.60 (m, 4 H, 2 × CH₂), 3.15-3.25 (m, 2 H, CH₂), 4.13 (q, 2 H, CH₂, J _HH = 7.2 Hz), 7.40 (bs, 1 H, NH). ¹³C NMR (75 MHz, CDCl₃) δ = 13.6 (CH₃), 14.7 (CH₃), 19.8 (CH₂), 20.8 (CH₂), 28.9 (CH₂), 31.9 (CH₂), 32.9 (CH₂), 44.2 (CH₂), 58.2 (CH₂), 91.9 (C), 164.8 (C), 168.4 (C). IR (neat): ν_NH = 3320 cm^-1. MS (EI): m/z (%) = 211 (43) [M⁺], 182 (9), 166 (28), 122 (100).

18 Chakraborti AK. Sharma L. Gulhane R. . Tetrahedron  2003,  59:  7661 

19a Filyakova VI. Karpenko NS. Kuznetsova OA. Pashkevich KI. Russ. J. Org. Chem.  1998,  34:  381 

19b

We confirmed the structure of 5d with NOE NMR experiments.

20 Katsuyama I. Ogawa S. Yamaguchi Y. Funabiki K. Matsui M. Muramatsu H. Shibata K. Synthesis  1997,  1321 

21 Naringrekar VH. Stella VJ. J. Pharm. Sci.  1990,  79:  138 

22 Fretz H. Gaugler M. Schneider J. Helv. Chim. Acta  2000,  83:  1145 

23 Sugita T. Eida M. Ito H. Komatsu N. Abe K. Suamapp M. J. Org. Chem.  1987,  52:  3789