tert-butyl N-[(3-hydroxycyclobutyl)methyl]carbamate

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

Procedure: Analogously to Example 1 b, but using ethyl acetate/hexane mixtures (1:3 and 1:1) in the flash chromatography, starting from 15.24 g (0.0757 mol) of 3-(N-BOC-aminomethyl)-cyclobutanol, 12.35 g (0.0757 mol) of N-hydroxyphthalimide, 19.85 g (0.0757 mol) of triphenylphosphine and 13.3 ml (0.0795 mol) of diethyl azodicarboxylate (93%), the title compound, which melts at 161°-162° C. after recrystallization from ethyl acetate, is obtained. Evaporation of the mother liquor and recrystallization of the residue from ethyl acetate/hexane gives a further batch of the title compound, m.p. 145°-150° C. the title compound, which melts at 161°-162° C. after recrystallization from ethyl acetate is obtained Evaporation of the mother liquor and recrystallization of the residue from ethyl acetate/hexane

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

Procedure: To an ice-cooled solution of (3-Hydroxy-cyclobutylmethyl)-carbamic acid tert-butyl ester (6.98 g, 34.7 mmol), 4-nitrobenzoic acid (11.59 g, 69.4 mmol) and triphenylphosphine (18.19 g, 69.4 mmol) in THF (1 L) was added a solution of DIAD (14.76 g, 69.4 mmol) in THF (10 mL). After removal of the ice bath, the mixture was stirred at RT for 15 h. The mixture was concentrated to dryness and the oily residue was purified normal phase column chromatography (elution with DCM) yielding the title intermediate as a yellow solid (9.89 g, 22.58 mmol, 65%), HPLC: FtRet=1.354; LC-MS: m/z 368.3 [M+NH4]+. After removal of the ice bath The mixture was concentrated to dryness the oily residue was purified normal phase column chromatography (elution with DCM)

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

Procedure: To an ice-cooled solution of (3-Hydroxy-cyclobutylmethyl)-carbamic acid tert-butyl ester (6.98 g, 34.7 mmol), 4-nitrobenzoic acid (11.59 g, 69.4 mmol) and triphenylphosphine (18.19 g, 69.4 mmol) in THF (1 L) was added a solution of DIAD (14.76 g, 69.4 mmol) in THF (10 mL). After removal of the ice bath, the mixture was stirred at RT for 15 h. The mixture was concentrated to dryness and the oily residue was purified normal phase column chromatography (elution with DCM) yielding the title intermediate as a yellow solid (9.89 g, 22.58 mmol, 65%), HPLC: FtRet=1.354; LC-MS: m/z 368.3 [M+NH4]+. After removal of the ice bath The mixture was concentrated to dryness the oily residue was purified normal phase column chromatography (elution with DCM)

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

Procedure: Analogously to Example 1 b, but using ethyl acetate/hexane mixtures (1:3 and 1:1) in the flash chromatography, starting from 15.24 g (0.0757 mol) of 3-(N-BOC-aminomethyl)-cyclobutanol, 12.35 g (0.0757 mol) of N-hydroxyphthalimide, 19.85 g (0.0757 mol) of triphenylphosphine and 13.3 ml (0.0795 mol) of diethyl azodicarboxylate (93%), the title compound, which melts at 161°-162° C. after recrystallization from ethyl acetate, is obtained. Evaporation of the mother liquor and recrystallization of the residue from ethyl acetate/hexane gives a further batch of the title compound, m.p. 145°-150° C. the title compound, which melts at 161°-162° C. after recrystallization from ethyl acetate is obtained Evaporation of the mother liquor and recrystallization of the residue from ethyl acetate/hexane