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Synlett 2010(10): 1485-1488  
DOI: 10.1055/s-0029-1220069
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

HClO4-SiO2 as a Novel and Recyclable Catalyst for the Phospha-Michael Addition of Phosphorous Nucleophiles to α,β-Unsaturated Malonates

Sara Sobhani*, Soodabeh Rezazadeh
Department of Chemistry, College of Sciences, Birjand University, Birjand 414, Iran
Fax: +98(561)2502009; e-Mail: ssobhani@birjand.ac.ir; e-Mail: sobhanisara@yahoo.com;
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Publication History

Received 19 December 2009
Publication Date:
25 May 2010 (online)

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Abstract

An efficient synthesis of β-phosphono malonates via phospha-Michael addition of phosphorous nucleophiles to α,β-unsaturated malonates in the presence of HClO4-SiO2 as a new and ­recyclable catalyst is described.

Key words

silica-supported perchloric acid - phospha-Michael addition - β-phosphono malonates

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General Procedure for the Synthesis of β-Phosphono Malonates (2a-t): HClO4-SiO2 (0.03 mmol, 0.057 g, 0.52 mmol/g) was added to a mixture of α,β-unsaturated malonates 1a-t (1 mmol) and P(OEt)3 (1 mmol). The mixture was stirred and monitored by TLC. After completion of the reaction, the reaction mixture was diluted with EtOAc and filtered. Evaporation of the solvent under reduced pressure gave the crude products. The pure products, 2a-t, were obtained by chromatography on silica, eluting with n-hexane-EtOAc (1:1).

(1-Phenyl-2,2-dicyanoethyl) Phosphonic Acid Diethyl Ester (2a)
¹H NMR (CDCl3): δ = 1.11 (t, 3 H, ³ J HH = 6.8 Hz), 1.33 (t, 3 H, ³ J HH = 7.0 Hz), 3.65 (dd, 1 H, ³ J HH = 8.0, ² J HP = 21.0 Hz), 3.91-4.21 (m, 4 H), 4.55 (t, 1 H, ³ J HH = 8.3 Hz), 7.43 (s, 5 H). ¹³C NMR (CDCl3): δ = 16.1 (d, ³ J CP = 5.6 Hz), 16.2 (d, ³ J CP = 5.6 Hz), 25.5, 44.6 (d, ¹ J CP = 144.0 Hz), 63.4 (d, ² J CP = 7.5 Hz), 64.4 (d, ² J CP = 7.0 Hz), 111.1 (d, ³ J CP = 12.5 Hz), 111.3 (d, ³ J CP = 10.0 Hz), 129.2, 129.3, 129.4, 129.8. ³¹P NMR (CDCl3): δ = 20.04. MS (70 eV): m/z = 292 [M+], 155 [M+ - P(O)(OEt)2].
[1-(2-Chlorophenyl)-2,2-dicyanoethyl] Phosphonic Acid Diethyl Ester (2b)
¹H NMR (CDCl3): δ = 1.11 (t, 3 H, ³ J HH = 7.0 Hz), 1.36 (t, 3 H, ³ J HH = 7.0 Hz), 3.75-4.30 (m, 4 H), 4.46 (dd, 1 H, ³ J HH = 8.2, ² J HP = 21.2 Hz), 4.61 (t, 1 H, ³ J HH = 8.5 Hz), 7.35 (d, 2 H, ³ J HH = 4.0 Hz), 7.47 (s, 1 H), 7.75 (d, 1 H, ³ J HH = 5.3 Hz). ¹³C NMR (CDCl3): δ = 16.0 (d, ³ J CP = 6.3 Hz), 16.2 (d, ³ J CP = 5.6 Hz), 24.9, 39.4 (d, ¹ J CP = 144.6 Hz), 63.6 (d, ² J CP = 7.5 Hz), 64.4 (d, ² J CP = 6.9 Hz), 110.9 (d, ³ J CP = 5.6 Hz), 111.1, 127.8, 128.6, 129.6, 130.6, 135.1. ³¹P NMR (CDCl3): δ = 19.47. MS (70 eV): m/z = 326 [M+], 328 [M+ + 2], 189 [M+ - P(O)(OEt)2], 191 [(M+ + 2) - P(O)(OEt)2].
[1-(4-Chlorophenyl)-2,2-dicyanoethyl] Phosphonic Acid Diethyl Ester (2d)
¹H NMR (CDCl3): δ = 1.16 (t, 3 H, ³ J HH = 7.0 Hz), 1.33 (t, 3 H, ³ J HH = 7.0 Hz), 3.62 (dd, 1 H, ³ J HH = 7.5 Hz, ² J HP = 21.5 Hz), 3.82-4.19 (m, 4 H), 4.55 (t, 1 H, ³ J HH = 7.7 Hz), 7.42 (s, 4 H). ¹³C NMR (CDCl3): δ = 16.1 (d, ³ J CP = 5.0 Hz), 16.2 (d, ³ J CP = 5.6 Hz), 25.5, 43.9 (d, ¹ J CP = 144.7 Hz), 63.5 (d, ² J CP = 7.0 Hz), 64.4 (d, ² J CP = 7.0 Hz), 111.0 (d, ³ J CP = 11.9 Hz), 111.2 (d, ³ J CP = 11.3 Hz), 128.8, 129.6, 130.7, 135.7. ³¹P NMR (CDCl3): δ = 19.42. MS (70 eV): m/z = 326 [M+], 328 [M+ + 2], 189 [M+ - P(O)(OEt)2], 191 [(M+ + 2) - P(O)(OEt)2].
[1-(Naphthalen-2-yl)-2,2-dicyanoethyl] Phosphonic Acid Diethyl Ester (2j)
¹H NMR (CDCl3): δ = 1.08 (t, 3 H, ³ J HH = 7.0 Hz), 1.36 (t, 3 H, ³ J HH = 7.0 Hz), 3.65-4.22 (m, 5 H), 4.66 (t, 1 H, ³ J HH = 8.5 Hz), 7.52-7.58 (m, 3 H), 7.87-7.96 (m, 4 H). ¹³C NMR (CDCl3): δ = 16.1 (d, ³ J CP = 5.6 Hz), 16.2 (d, ³ J CP = 6.2 Hz), 25.7, 44.8 (d, ¹ J CP = 144.0 Hz), 63.4 (d, ² J CP = 7.5 Hz), 64.4 (d, ² J CP = 7.0 Hz), 111.2 (d, ³ J CP = 13.2 Hz), 111.3 (d, ³ J CP = 8.2 Hz), 125.9, 126,9, 127.2, 127.6, 127.7, 127.8, 128.2, 129.2, 129.4, 133.3. ³¹P NMR (CDCl3): δ = 19.95.
[1-(Furan-2-yl)-2,2-dicyanoethyl] Phosphonic Acid Diethyl Ester (2k)
¹H NMR (CDCl3): δ = 1.24-1.37 (m, 6 H), 3.87 (dd, 1 H, ³ J HH = 6.5 Hz, ² J HP = 22.7 Hz), 3.98-4.23 (m, 4 H), 4.51 (t, 1 H, ³ J HH = 8.7 Hz), 6.44 (s, 1 H), 6.62 (s, 1 H), 7.49 (s, 1 H).
¹³C NMR (CDCl3): δ = 16.1, 16.2, 24.3, 39.1 (d, ¹ J CP = 147.1 Hz), 63.9 (d, ² J CP = 6.9 Hz), 64.2 (d, ² J CP = 6.9 Hz), 110.9 (d, ³ J CP = 9.4 Hz), 111.1 (d, ³ J CP = 11.9 Hz), 111.3, 111.7, 143.2, 144.0. ³¹P NMR (CDCl3): δ = 19.88. MS (70 eV): m/z = 282 [M+], 145 [M+ -P(O)(OEt)2].
[1-(Pyridin-3-yl)-2,2-dicyanoethyl] Phosphonic Acid Diethyl Ester (2m)
¹H NMR (CDCl3): δ = 1.18 (t, 3 H, ³ J HH = 6.8 Hz), 1.33 (t, 3 H, ³ J HH = 7.0 Hz), 3.65 (dd, 1 H, ³ J HH = 6.8 Hz, ² J HP = 21.6 Hz), 3.92-4.21 (m, 4 H), 4.63 (t, 1 H, ³ J HH = 8.5 Hz), 7.39 (t, 1 H, ³ J HH = 6.5 Hz), 7.95 (d, 1 H, ³ J HH = 6.5 Hz), 8.67 (s, 2 H). ¹³C NMR (CDCl3): δ = 16.1 (d, ³ J CP = 5.0 Hz), 16.2 (d, ³ J CP = 5.0 Hz), 25.3, 42.1 (d, ¹ J CP = 144.6 Hz), 63.8 (d, ² J CP = 7.0 Hz), 64.5 (d, ² J CP = 7.0 Hz), 110.8 (d, ³ J CP = 10.7 Hz), 111.0 (d, ³ J CP = 11.9 Hz), 124.0, 126,7, 136.5, 150.5, 150.8. ³¹P NMR (CDCl3): δ = 19.03. MS (70 eV): m/z = 293 [M+], 156 [M+ - P(O)(OEt)2].