ethyl 2-(cyclopentylamino)acetate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: CBZ-L-Valine (15.1 g, 0.06 mol) was dissolved in CH2Cl2 (250 mL) and the following reagents were added in equal molar amounts in the stated order; 4-Dimethylaminopyridine (DMAP), ethyl-N-(cyclopentyl)glycinate and WSCDI. The reaction mixture was allowed to stir at room temperature over night. Evaporation of the solvent yielded a viscous semisolid which was treated with ethyl acetate and then diluted with HCl (4:1) and separated. The organic extract was washed with 1N HCl followed by 5% aqueous Na2CO3 and saturated aqueous NaCl-solution. After drying over MgSO4, filtration and evaporation under reduced pressure yielded an oil (25.1 g) which was purified over silica gel using CH2Cl2 as eluent. The product was collected (6.6 g) as a semisolid. (Rf=0.3, silica gel, CH2Cl2 :CH3OH; 97:3). the following reagents were added in equal molar amounts in the stated order Evaporation of the solvent yielded a viscous semisolid which separated The organic extract was washed with 1N HCl After drying over MgSO4, filtration and evaporation under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Cyclopentylamine (85.2 g, 1.0 mol) and triethylamine (101.2 g, 1.0 mol) were dissolved in tetrahydrofuran (750 mL) and cooled to 0°-5° C. by means of an ice-water bath. Ethyl bromoacetate (167 g, 1.0 mol) was added dropwise at 0°-5° C. to the solution. After addition the mixture was allowed to warm up to room temperature and then stirred over night at ambient temperature. The precipitated white triethylamine hydrochloride was filtered off and the filtrate concentrated to an oil which was purified over silica gel using hexane/ethyl acetate (8.2) as the eluent. The collected product was dissolved in ether and cooled by means of an ice water bath. Dry hydrogen chloride was bubbled into the solution whereby the HCL salt of the product precipitated. Filtration yielded 138 g of product as a white solid melting at 174°-176° C. cooled to 0°-5° C. by means of an ice-water bath After addition the mixture The precipitated white triethylamine hydrochloride was filtered off the filtrate concentrated to an oil which was purified over silica gel The collected product was dissolved in ether cooled by means of an ice water bath Dry hydrogen chloride was bubbled into the solution whereby the HCL salt of the product precipitated Filtration