tert-butyl 3-benzylpiperazine-1-carboxylate

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

Procedure: Following the procedure of steps 2 and 4 of Example 1, 5-bromo-2,3-dihydro-indole-1-carboxylic acid tert-butyl ester (0.48 g, 1.6 mmol) was coupled with 3-benzyl-piperazine-1-carboxylic acid tert-butyl ester to give 5-(2-benzyl-4-tert-butoxycarbonyl-piperazin-1-yl)-2,3-dihydro-indole-1-carboxylic acid tert-butyl ester, which was then deprotected by reaction with TFA to afford 5-(2-benzyl-piperazin-1-yl)-2,3-dihydro-1H-indole (0.16 g) as a yellow foam; 1H NMR (300, MHz, CDCl3) δ 7.24-7.10 (m, 3H), 7.17-1.01 (m, 2H), 6.96 (d, J=2.2 Hz, 1H), 6.82 (dd, J=8.2, 2.2 Hz, 1H), 3.61-3.46 (m, 3H), 3.20-2.69 (m, 7H), 2.84-2.72 (m, 2H), 2.56 (dd, J=10.5, 13.6 Hz, 1H); MS (M+H)=294.

Conditions: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a mixture of Pd(OAc)2 (0.054 g, 0.2 mmol), NaOtBu (0.64 g, 6.6 mmol) in xylene (7.0 mL) in a screw-capped tube was added tBu3P (0.049 g, 0.2 mmol). After 10 minutes a solution of 5-bromo-1-(tert-butyl-dimethyl-silanyl)-1H-indole (1.30 g, 4.4 mmol) in xylene (7.0 mL) and a solution of 3-benzyl-piperazine-1-carboxylic acid tert-butyl ester (1.34 g, 4.8 mmol) in xylene (8.0 mL) were added. The mixture was heated to 80° C. for 30 minutes, then cooled to room temperature. The reaction mixture was taken up in ethyl acetate, filtered through a pad of celite, and concentrated under reduced pressure. Purification via flash chromatography (gradient: 2% to 20% EtOAc in hexane) afforded 3-Benzyl-4-[1-(tert-butyl-dimethyl-silanyl)-1H-indol-5-yl]-piperazine-1-carboxylic acid tert-butyl ester (1.65 g, 74%) as a pale yellow solid; MS (M+H)=506. cooled to room temperature filtered through a pad of celite concentrated under reduced pressure Purification via flash chromatography (gradient: 2% to 20% EtOAc in hexane)

Conditions: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a mixture of Pd(OAc)2 (0.054 g, 0.2 mmol), NaOtBu (0.64 g, 6.6 mmol) in xylene (7.0 mL) in a screw-capped tube was added tBu3P (0.049 g, 0.2 mmol). After 10 minutes a solution of 5-bromo-1-(tert-butyl-dimethyl-silanyl)-1H-indole (1.30 g, 4.4 mmol) in xylene (7.0 mL) and a solution of 3-benzyl-piperazine-1-carboxylic acid tert-butyl ester (1.34 g, 4.8 mmol) in xylene (8.0 mL) were added. The mixture was heated to 80° C. for 30 minutes, then cooled to room temperature. The reaction mixture was taken up in ethyl acetate, filtered through a pad of celite, and concentrated under reduced pressure. Purification via flash chromatography (gradient: 2% to 20% EtOAc in hexane) afforded 3-Benzyl-4-[1-(tert-butyl-dimethyl-silanyl)-1H-indol-5-yl]-piperazine-1-carboxylic acid tert-butyl ester (1.65 g, 74%) as a pale yellow solid; MS (M+H)=506. cooled to room temperature filtered through a pad of celite concentrated under reduced pressure Purification via flash chromatography (gradient: 2% to 20% EtOAc in hexane)

Conditions: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a mixture of Pd(OAc)2 (0.054 g, 0.2 mmol), NaOtBu (0.64 g, 6.6 mmol) in xylene (7.0 mL) in a screw-capped tube was added tBu3P (0.049 g, 0.2 mmol). After 10 minutes a solution of 5-bromo-1-(tert-butyl-dimethyl-silanyl)-1H-indole (1.30 g, 4.4 mmol) in xylene (7.0 mL) and a solution of 3-benzyl-piperazine-1-carboxylic acid tert-butyl ester (1.34 g, 4.8 mmol) in xylene (8.0 mL) were added. The mixture was heated to 80° C. for 30 minutes, then cooled to room temperature. The reaction mixture was taken up in ethyl acetate, filtered through a pad of celite, and concentrated under reduced pressure. Purification via flash chromatography (gradient: 2% to 20% EtOAc in hexane) afforded 3-Benzyl-4-[1-(tert-butyl-dimethyl-silanyl)-1H-indol-5-yl]-piperazine-1-carboxylic acid tert-butyl ester (1.65 g, 74%) as a pale yellow solid; MS (M+H)=506. cooled to room temperature filtered through a pad of celite concentrated under reduced pressure Purification via flash chromatography (gradient: 2% to 20% EtOAc in hexane)