Reaction #9830

Reaction equation

Ethyl acetate

2,3-Dihydro-benzo[1,4]dioxin-5-ylamine

2-chloroethanol

Hunigs base

→

crude product

Yield 80.0%

2-[(2,3-Dihydro-benzo[1,4]dioxin-5-yl)-(2-hydroxy-ethyl)-amino]-ethanol

Yield 80.0%

Conditions

Workup

1. 1
   Washthe solution is washed with diluted brine (1×250 mL)
2. 2
   Washis back-washed with ethyl acetate (2×100 mL)
3. 3
   Extractionextracted with 2N HCl (3×150 mL)
4. 4
   Extractionextracted with ethyl acetate (3×100 mL)
5. 5
   DryingThe organic phase is dried with MgSO4
6. 6
   Concentrationconcentrated
7. 7
   Otherto remove residual chloroethanol

Procedure

2,3-Dihydro-benzo[1,4]dioxin-5-ylamine (31.1 g, 0.2 mol) is mixed with 2-chloroethanol (210 mL, 3.1 mol) and Hunigs base (105 mL, 0.6 mol). The resulting dark solution is heated to 120° C. and stirred at this temperature with continuous monitoring by HPLC. After 12.5 h, the reaction is stopped. Ethyl acetate (300 mL) is added and the solution is washed with diluted brine (1×250 mL) followed by brine (2×75 mL). All aqueous layers are combined, the pH adjusted to 7 with K2CO3, and solution is back-washed with ethyl acetate (2×100 mL). All organic layers are then combined and extracted with 2N HCl (3×150 mL). The resulting aqueous solution is neutralized with solid K2CO3 to pH 7 and extracted with ethyl acetate (3×100 mL). The organic phase is dried with MgSO4, concentrated and chased with toluene (2×50 mL) to remove residual chloroethanol. 39.6 g (80%) of crude product is obtained as a dark oil of 94 area % (LC-MS) purity. 1H NMR (CDCl3) δ 6.88–6.70 (m, 3H), 4.34–4.22 (m, 4H), 3.54 (t, J=7.5 Hz, 4H), 3.18 (t, J=7.5 Hz, 4H).

Source