1,4-Bis(1,1-dimethylethyl) 1,4-piperazinedicarboxylate

General procedure: A round-bottom flask (10 mL), which contains EtOH(5 mL), was charged with a solution of diboc (1–2 mmol), nano-FeFor the N-boc protection of amines, to solution of diboc (1 mmol) in ethanol (5 ml) was added {K*18-crown-6]Br3}n (0.001 mmol). The solution was stirred at room temperature for 1 min. The amine (1 mmol) was then added and solution as stirred at room temperature for an appropriate time (table 1). After completion of the reaction, the solvent was removed by water bath distillation. To the residue was added ethyl acetate (5 ml) and the mixture was filtered (the catalyst is insoluble in n-hexane and ethyl acetate). The solid was washed with ethyl acetate ()10 ml*2) amd combined filtrates were reduced to dryness to yield the pure products.General procedure: To a mixture of amine (1.0 mmol) and (Boc)To a cold methylene chloride solution (10 ml) of piperazine (30.23 mmol, 2.60 g) was added methylene chloride solution (10 ml) of BOC anhydride (1.50 mmol) and the mixture was stirred at 0°C for 1 hour. After the reaction is complete, water is added and the aqueous K2CO3 solution is added to make the reaction mixture basic. All of the reaction mixture was extracted with methylene chloride and the product was isolated by column chromatography.General procedure: A round-bottom flask (10 mL), which contains EtOH(5 mL), was charged with a solution of diboc (1–2 mmol), nano-FeFor the N-boc protection of amines, to solution of diboc (1 mmol) in ethanol (5 ml) was added {K*18-crown-6]Br3}n (0.001 mmol). The solution was stirred at room temperature for 1 min. The amine (1 mmol) was then added and solution as stirred at room temperature for an appropriate time (table 1). After completion of the reaction, the solvent was removed by water bath distillation. To the residue was added ethyl acetate (5 ml) and the mixture was filtered (the catalyst is insoluble in n-hexane and ethyl acetate). The solid was washed with ethyl acetate ()10 ml*2) amd combined filtrates were reduced to dryness to yield the pure products.General procedure: To a mixture of amine (1.0 mmol) and (Boc)To a cold methylene chloride solution (10 ml) of piperazine (30.23 mmol, 2.60 g) was added methylene chloride solution (10 ml) of BOC anhydride (1.50 mmol) and the mixture was stirred at 0°C for 1 hour. After the reaction is complete, water is added and the aqueous K2CO3 solution is added to make the reaction mixture basic. All of the reaction mixture was extracted with methylene chloride and the product was isolated by column chromatography.General procedure: A series of example carbamates CA were produced by a first methodusing polyamines and di-tert-butyl dicarbonate as starting materials to yield carbamates CA. All reactions were performed in THE at 25 00 with triethylamine as catalyst and using an equimolar amount of di-tert-butyl dicarbonate with respect to amino groups. In all cases, the corresponding carbamates could be obtained with between 90 and 99percent yield andcharacterized by 1H-NMR and 130-NMR and ET-IR spectroscopy. The chemical names of the polyamines used and the corresponding carbamates CA obtained are given in Table 1. The reactants (including the amines) were all purchased from Sigma Aldrich, Switzerland, except for the amines used for CA4 and CA5, which were purchased from Huntsman Corp., USA.To a cold methylene chloride solution (10 ml) of piperazine (30.23 mmol, 2.60 g) was added methylene chloride solution (10 ml) of BOC anhydride (1.50 mmol) and the mixture was stirred at 0°C for 1 hour. After the reaction is complete, water is added and the aqueous K2CO3 solution is added to make the reaction mixture basic. All of the reaction mixture was extracted with methylene chloride and the product was isolated by column chromatography.To a cold methylene chloride solution (10 ml) of piperazine (30.23 mmol, 2.60 g) was added methylene chloride solution (10 ml) of BOC anhydride (1.50 mmol) and the mixture was stirred at 0 ° C for 1 hour. After the reaction was terminated, water was added and the aqueous K2CO3 solution was added to make the reaction mixture basic. All of the reaction mixture was extracted with methylene chloride and the product was isolated by column chromatography.General procedure: A round-bottom flask (10 mL), which contains EtOH(5 mL), was charged with a solution of diboc (1'2 mmol), nano-Fe3O4 (3 molpercent, 0.007 g) and the amine (1 mmol). The mixture was stirred at room temperature for the appropriate time (Table 3). After completion of the reaction, the catalyst was collected by a magnet and separated from the solution of product and the remaining starting materials.After drying and evaporation of the solvent, the resulting solid was recrystallized from n-hexane or ethyl acetate(5 mL) to give the pure product. The recovered catalyst was washed with EtOH, dried and reused for the next run. The catalyst was recovered and reused for six times without any significant changes in the yield and the reaction time.For the N-boc protection of amines, to solution of diboc (1 mmol) in ethanol (5 ml) was added {K*18-crown-6]Br3}n (0.001 mmol). The solution was stirred at room temperature for 1 min. The amine (1 mmol) was then added and solution as stirred at room temperature for an appropriate time (table 1). After completion of the reaction, the solvent was removed by water bath distillation. To the residue was added ethyl acetate (5 ml) and the mixture was filtered (the catalyst is insoluble in n-hexane and ethyl acetate). The solid was washed with ethyl acetate ()10 ml*2) amd combined filtrates were reduced to dryness to yield the pure products.General procedure: To a mixture of amine (1.0 mmol) and (Boc)2O (1.2 mmol), copper nano particles (0.1 mmol) was added with vigorous stirring at room temperature or 70 oC for the appropriate time (Scheme 2 and Table 2) until disappearance of the precursor amine was observed in the TLC. After completion, the reaction mixture was diluted with dry ether (5 mL) and catalyst was separated by filtration and the residue was washed with ether. The combined filtrate was evaporated to dryness and dried under vacuum. The N-Boc product is essentially pure on TLC but for getting analytical data the sample was passed through silica-gel (100-200 mesh) column using 10-30percent ethyl acetate in hexane as eluent. The physical data (m.p., FTIR, NMR) of the known compounds were found to be identical with those reported in the literature.

Molecular Weight:286.37
XLogP3:1.8
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:4
Exact Mass:286.18925731
Monoisotopic Mass:286.18925731
Topological Polar Surface Area:59.1
Heavy Atom Count:20
Complexity:324
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes