Diethyl squarate → [2-[(2-Ethoxy-3,4-dioxo-1-cyclobuten-1-yl)amino]ethyl]phosphonic acid diethyl ester

HRID 2255467Notes

Reaction equation

HRID 2255467 reaction equation
C(O[C:4]1[C:5](=[O:12])[C:6](=[O:11])[C:7]=1[O:8][CH2:9][CH3:10])C.[CH2:13]([O:15][P:16]([CH2:21][CH2:22][NH2:23])(=[O:20])[O:17][CH2:18][CH3:19])[CH3:14]>C(O)C>[CH2:18]([O:17][P:16]([CH2:21][CH2:22][NH:23][C:4]1[C:5](=[O:12])[C:6](=[O:11])[C:7]=1[O:8][CH2:9][CH3:10])(=[O:20])[O:15][CH2:13][CH3:14])[CH3:19]

Participants

4

Reactant 2

HCID 123228Diethyl squarateHCID 2733596Diethyl (2-aminoethyl)phosphonate

Product 1

HCID 10063672[2-[(2-Ethoxy-3,4-dioxo-1-cyclobuten-1-yl)amino]ethyl]phosphonic acid diethyl ester

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent2×

Procedure

To a solution of 3,4-diethoxy-3-cyclobutene-1,2-dione (4.00 g, 23.5 mmol) in ethanol (100 mL) was added 2-aminoethylphosphonic acid diethyl ester (5.43 g, 30.0 mmol) in ethanol (100 mL) over a 1 hour period. After leaving overnight the reaction mixture was preadsorbed onto silica gel and purified by flash chromatography (5.5 cm diameter, gradient elution with 2.5-10% isopropanol in dichloromethane) to yield [2-[(2-ethoxy-3,4-dioxo-1-cyclobuten-1-yl)amino]ethyl]phosphonic acid diethyl ester as an oil which solidifies on standing (3.98 g, 55%, mp 66°-68° C.); IR (KBr, cm-1): 3400, 3180, 1800, 1700, 1600; MS (+FAB): 306 (MH+, 100), 278 (14), 137 (14), 109 (35); 1H NMR (CDCl3, 400 MHz): δ6.58, 6.46 (br s, NH), 4.75 (br m, 2H), 4.21-4.07 (m, 4H), 4.00, 3.75 (br m, 2H), 2.08 (d of t, J=17.5 and 6.5 Hz, 2H), 1.46 (br m, 3H), 1.35 (t, J=7 Hz, 6H).

Workup

  1. customAfter leaving overnight the reaction mixture
  2. custompurified by flash chromatography (5.5 cm diameter, gradient elution with 2.5-10% isopropanol in dichloromethane)

Sources & evidence

ORD record
ord-c72bea0434ea40a89b9237ae94583a50
Source dataset
uspto-grants-1993_08
Patent number
US05240946

Reaction notes

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