benzyl N-(2-oxoazetidin-3-yl)carbamate

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: A solution of 118 mg (0.5 mmole) of N-hydroxy-3-(Cbz-amino)-2-azetidinone, prepared as described by Example 3, in 10 ml of tetrahydrofuran and 10 ml of water at pH 7 was added to a flask equipped with a magnetic stirrer, a buret, and a pH electrode. The solution was maintained under nitrogen and was treated with a solution of 0.8 ml of 20% titanium trichloride by dropwise addition from a syringe. The pH of the reaction mixture was maintained at 7.0 during the addition of the TiCl3 by the addition of 3.0N sodium hydroxide through the buret as needed. After the addition was complete the reaction mixture was stirred at room temperature for 2 hours. The pH of the reaction mixture was adjusted to 8.0, transferred to a separatory funnel and extracted with three 25 ml portions of ethyl acetate. The combined ethyl acetate was washed with 10 ml of brine, dried over magnesium sulfate, filtered and evaporated to dryness. The residue was recrystallized from ethyl acetate-hexanes to give 69 mg (60%) of 3-(Cbz-amino)-2-azetidinone as a white solid melting at about 160° C. to about 161° C. equipped with a magnetic stirrer The solution was maintained under nitrogen After the addition transferred to a separatory funnel extracted with three 25 ml portions of ethyl acetate The combined ethyl acetate was washed with 10 ml of brine dried over magnesium sulfate filtered evaporated to dryness The residue was recrystallized from ethyl acetate-hexanes

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

Procedure: A solution of 118 mg (0.5 mmole) of N-hydroxy-3-(Cbz-amino)-2-azetidinone, prepared as described by Example 3, in 10 ml of tetrahydrofuran and 10 ml of water at pH 7 was added to a flask equipped with a magnetic stirrer, a buret, and a pH electrode. The solution was maintained under nitrogen and was treated with a solution of 0.8 ml of 20% titanium trichloride by dropwise addition from a syringe. The pH of the reaction mixture was maintained at 7.0 during the addition of the TiCl3 by the addition of 3.0N sodium hydroxide through the buret as needed. After the addition was complete the reaction mixture was stirred at room temperature for 2 hours. The pH of the reaction mixture was adjusted to 8.0, transferred to a separatory funnel and extracted with three 25 ml portions of ethyl acetate. The combined ethyl acetate was washed with 10 ml of brine, dried over magnesium sulfate, filtered and evaporated to dryness. The residue was recrystallized from ethyl acetate-hexanes to give 69 mg (60%) of 3-(Cbz-amino)-2-azetidinone as a white solid melting at about 160° C. to about 161° C. equipped with a magnetic stirrer The solution was maintained under nitrogen After the addition transferred to a separatory funnel extracted with three 25 ml portions of ethyl acetate The combined ethyl acetate was washed with 10 ml of brine dried over magnesium sulfate filtered evaporated to dryness The residue was recrystallized from ethyl acetate-hexanes

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: 1-Methoxalyl-3-benzyloxycarbonylamino-2-azetidinone (240 mg.) was dissolved in methanol (10 ml.), and sodium methylate (6 mg.) was added to said solution, and then the mixture was heated under reflux for 45 minutes. The methanol was distilled off from the reaction mixture, and the residue was washed with ether to give crude 3-benzyloxycarbonylamino-2-azetidinone (126 mg.). Furthermore, this product was recrystallized from acetone to give the purified compound (50 mg.). And, the purified same compound (54 mg.) was recovered from the mother liquor. Total yield was 104 mg. Mp 164° to 165° C. the mixture was heated under reflux for 45 minutes The methanol was distilled off from the reaction mixture the residue was washed with ether

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

Procedure: 1-Methoxalyl-3-benzyloxycarbonylamino-2-azetidinone (240 mg.) was dissolved in methanol (10 ml.), and sodium methylate (6 mg.) was added to said solution, and then the mixture was heated under reflux for 45 minutes. The methanol was distilled off from the reaction mixture, and the residue was washed with ether to give crude 3-benzyloxycarbonylamino-2-azetidinone (126 mg.). Furthermore, this product was recrystallized from acetone to give the purified compound (50 mg.). And, the purified same compound (54 mg.) was recovered from the mother liquor. Total yield was 104 mg. Mp 164° to 165° C. the mixture was heated under reflux for 45 minutes The methanol was distilled off from the reaction mixture the residue was washed with ether

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

Procedure: 1-Methoxalyl-3-benzyloxycarbonylamino-2-azetidinone (240 mg.) was dissolved in methanol (10 ml.), and sodium methylate (6 mg.) was added to said solution, and then the mixture was heated under reflux for 45 minutes. The methanol was distilled off from the reaction mixture, and the residue was washed with ether to give crude 3-benzyloxycarbonylamino-2-azetidinone (126 mg.). Furthermore, this product was recrystallized from acetone to give the purified compound (50 mg.). And, the purified same compound (54 mg.) was recovered from the mother liquor. Total yield was 104 mg. Mp 164° to 165° C. the mixture was heated under reflux for 45 minutes The methanol was distilled off from the reaction mixture the residue was washed with ether

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

Procedure: To a solution of 3-benzyloxycarbonylamino-2-azetidinone (5.0 g) in dry tetrahydrofuran (125 ml), cooled to -78° C., was added sec-butyl lithium (18.5 ml) and the mixture was stirred for 5 minutes. Ethyl chlorophenylphosphonate (4.71 g) was added and the mixture was stirred for 1 hour at -78° C. followed by the addition of 125 ml of saturated sodium chloride solution. The mixture was then extracted twice with 125 ml portions of ethyl acetate and the extracts were combined, dried over anhydrous sodium sulfate and the solvent removed in vacuo yielding the crude product as a foam. The crude product was purified by chromatography on silica gel (750 g), eluting with dichloromethane:ethyl acetate (1:1) followed by ethyl acetate. The ethyl acetate fractions were stripped and the residue triturated with ether to yield 4.94 g of product. the mixture was stirred for 1 hour at -78° C. The mixture was then extracted twice with 125 ml portions of ethyl acetate dried over anhydrous sodium sulfate the solvent removed in vacuo yielding the crude product as a foam The crude product was purified by chromatography on silica gel (750 g) eluting with dichloromethane:ethyl acetate (1:1) the residue triturated with ether