Synlett 2009(6): 917-920  
DOI: 10.1055/s-0028-1087960
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Indium Trichloride Catalyzed One-Pot Synthesis of New (2-Amino-3-cyano-4H-chromen-4-yl) Phosphonic Acid Diethyl Ester

Parthasarathy Jayashree, Gnanamani Shanthi, Paramasivan T. Perumal*
Organic Chemistry Division, Central Leather Research Institute, Adyar, Chennai 600020, India
Fax: +91(44)24911589; e-Mail: ptperumal@gmail.com;
Further Information

Publication History

Received 12 December 2008
Publication Date:
16 March 2009 (online)

Abstract

A one-pot synthesis of new (2-amino-3-cyano-4H-chromen-4-yl) phosphonic acid diethyl ester was achieved in good yields by indium trichloride catalyzed three-component reaction of salicylaldehyde and malononitrile with triethyl phosphite.

13

(2-Amino-3-cyano-4 H -chromen-4-yl) Phosphonic Acid Diethyl Ester (4a, Table 1, Entry 1); Typical Procedure
To a stirred mixture of salicylaldehyde (1 mmol) and malononitrile (1 mmol) in EtOH, triethyl phosphite, and InCl3 (20 mol%) was added. The reaction mixture was stirred at r.t. for the appropriate time (Table  [¹] ). After complete conversion as indicated by TLC, the mixture was poured into ice and extracted with EtOAc. The organic extracts were washed with brine solution, dried over Na2SO4, and concentrated under vacuum to yield pure product 4a.

14

(2-Amino-3-cyano-4 H -chromen-4-yl) Phosphonic Acid Diethyl Ester (4a, Table 1, Entry 1)
White solid; mp 140-142 ˚C. IR (KBr): νmax = 3349, 3167, 2189, 1648, 1422, 1233, 1030 cm. ¹H NMR (500 MHz, DMSO-d 6): δ = 1.09 (t, 3 H, J = 6.9 Hz), 1.14 (t, 3 H, J = 6.85 Hz), 3.87 (m, 4 H), 4.04 (d, 1 H, ² J PH = 17.6 Hz), 6.97 (d, 1 H, J = 8.4 Hz), 7.10 (t, 1 H, J = 6.85 Hz), 7.14 (br s, 2 H, NH2, D2O exchangeable), 7.22 (m, 2 H). ¹³C NMR (75 MHz, DMSO-d 6): δ = 16.1, 16.2, 34.5 (d, ¹ J CP = 144.0 Hz), 47.3 (d, ² J CP = 7.5 Hz), 62.1 (d, ² J CP = 7.5 Hz), 62.2 (d, ² J CP = 6.75 Hz), 115.9, 117.7, 120.1, 124.2, 128.8, 129.4, 149.9, 162.6. ³¹P NMR (202.5 MHz, DMSO-d 6): δ = 23.17. MS: m/z = 308 [M+]. Anal. Calcd (%) for C14H17N2O4P: C, 54.55; H, 5.56; N, 9.09. Found: C, 54.50; H, 5.52; N, 9.03.
(2-Amino-6-bromo-3-cyano-4 H -chromene-4-yl) Phosphonic Acid Diethyl Ester (4f, Table 1, Entry 6)
White solid; mp 180-182 ˚C. IR (KBr): νmax = 3353, 3156, 2190, 1655, 1417, 1241, 1040 cm. ¹H NMR (300 MHz, DMSO-d 6): δ = 1.13 (m, 6 H), 3.91 (m, 4 H), 4.17 (d, 1 H, ² J PH = 18.0 Hz), 6.99 (d, 1 H, J = 8.7 Hz), 7.26 (br s, 2 H, NH2, D2O exchangeable), 7.44 (m, 2 H). ¹³C NMR (75 MHz, DMSO-d 6): δ = 16.1, 16.2, 34.1 (d, ¹ J CP = 144.0 Hz), 47.0 (d, ² J CP = 7.5 Hz), 62.2 (d, ² J CP = 7.5 Hz), 62.4 (d, ² J CP = 7.5 Hz), 115.6, 118.1, 119.8, 120.4, 131.4, 131.8, 149.2, 162.3. ³¹P NMR (202.5 MHz, DMSO-d 6): δ = 22.64. MS: m/z = 387 [M+], 389 [M + 2]. Anal. Calcd (%) for C14H16BrN2O4P: C, 43.43; H, 4.17; N, 7.24. Found: C, 43.38; H, 4.11; N, 7.20.