1-O-tert-butyl 2-O-ethyl 4-oxopiperidine-1,2-dicarboxylate

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

Procedure: To a suspension of 0.75 g (0.019 mol, 60% by weight in oil) of sodium hydride (washed three times with hexanes) in 40 ml of THF was added 3.34 g (0.019 mol) of diethylcyanomethylphosphonate. After stirring the reaction mixture for thirty minutes at room temperature, a solution of 4.26 g (0.016 mol) of ethyl 4-oxo-N-t-butoxycarbonyl-2-piperidinecarboxylate in 10 ml of THF was added. The mixture was stirred for 30 minutes at room temperature and 90 minutes at the reflux temperature of the reaction mixture, then cooled to room temperature and quenched with water. The organic layer was separated and the aqueous layer extracted twice with diethyl ether. The organic extracts were combined, dried over anhydrous magnesium sulfate, filtered and concentrated under vacuum. High pressure liquid chromatography of the residue afforded 3.58 g of ethyl 4-cyanomethylidene-N-t-butoxycarbonyl-2-piperidinecarboxylate. The mixture was stirred for 30 minutes at room temperature and 90 minutes at the reflux temperature of the reaction mixture cooled to room temperature quenched with water The organic layer was separated the aqueous layer extracted twice with diethyl ether dried over anhydrous magnesium sulfate filtered concentrated under vacuum

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

Procedure: To a 1 l. 138 round bottom flask was added 33.6 g (0.16 mol) of pyridinium chlorochromate, 35 g of powdered 4A molecular sieves and 200 ml of methylene chloride. After stirring the mixture at room temperature for sixty minutes, a solution of 21.3 g (0.078 mol) of ethyl cis-4-hydroxy-N-t-butoxycarbonyl-2-piperidinecarboxylate in 50 ml of methylene chloride was added. After stirring the mixture for sixty minutes at room temperature, 700 ml of diethyl ether was added. The mixture was filtered through three-fourths inch of Celite and three-fourths inch of silica gel (230-400 mesh) in a 650 ml medium porosity sintered glass funnel. The solids were washed with 1 1. of diethyl ether and the filtrate was concentrated under vacuum. To the residue was added 200 ml of diethyl ether and the mixture filtered through three-eighths inch of Celite and three-eighths inch of silica gel (230-400 mesh) in a 150 ml medium porosity sintered glass funnel. The solids were washed with 500 ml of diethyl ether and the filtrate was concentrated under vacuum. The residue was purified by high pressure liquid chromatography to provide 14.6 g of ethyl 4-oxo-N-t-butoxycarbonyl-2-piperidinecarboxylate as a colorless oil. After stirring the mixture for sixty minutes at room temperature The mixture was filtered through three-fourths inch of Celite and three-fourths inch of silica gel (230-400 mesh) in a 650 ml medium porosity sintered glass funnel The solids were washed with 1 1 of diethyl ether and the filtrate was concentrated under vacuum To the residue was added 200 ml of diethyl ether the mixture filtered through three-eighths inch of Celite and three-eighths inch of silica gel (230-400 mesh) in a 150 ml medium porosity sintered glass funnel The solids were washed with 500 ml of diethyl ether the filtrate was concentrated under vacuum The residue was purified by high pressure liquid chromatography

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

Procedure: To a 1 l. 138 round bottom flask was added 33.6 g (0.16 mol) of pyridinium chlorochromate, 35 g of powdered 4A molecular sieves and 200 ml of methylene chloride. After stirring the mixture at room temperature for sixty minutes, a solution of 21.3 g (0.078 mol) of ethyl cis-4-hydroxy-N-t-butoxycarbonyl-2-piperidinecarboxylate in 50 ml of methylene chloride was added. After stirring the mixture for sixty minutes at room temperature, 700 ml of diethyl ether was added. The mixture was filtered through three-fourths inch of Celite and three-fourths inch of silica gel (230-400 mesh) in a 650 ml medium porosity sintered glass funnel. The solids were washed with 1 1. of diethyl ether and the filtrate was concentrated under vacuum. To the residue was added 200 ml of diethyl ether and the mixture filtered through three-eighths inch of Celite and three-eighths inch of silica gel (230-400 mesh) in a 150 ml medium porosity sintered glass funnel. The solids were washed with 500 ml of diethyl ether and the filtrate was concentrated under vacuum. The residue was purified by high pressure liquid chromatography to provide 14.6 g of ethyl 4-oxo-N-t-butoxycarbonyl-2-piperidinecarboxylate as a colorless oil. After stirring the mixture for sixty minutes at room temperature The mixture was filtered through three-fourths inch of Celite and three-fourths inch of silica gel (230-400 mesh) in a 650 ml medium porosity sintered glass funnel The solids were washed with 1 1 of diethyl ether and the filtrate was concentrated under vacuum To the residue was added 200 ml of diethyl ether the mixture filtered through three-eighths inch of Celite and three-eighths inch of silica gel (230-400 mesh) in a 150 ml medium porosity sintered glass funnel The solids were washed with 500 ml of diethyl ether the filtrate was concentrated under vacuum The residue was purified by high pressure liquid chromatography

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

Procedure: To a suspension of 0.75 g (0.019 mol, 60% by weight in oil) of sodium hydride (washed three times with hexanes) in 40 ml of THF was added 3.34 g (0.019 mol) of diethylcyanomethylphosphonate. After stirring the reaction mixture for thirty minutes at room temperature, a solution of 4.26 g (0.016 mol) of ethyl 4-oxo-N-t-butoxycarbonyl-2-piperidinecarboxylate in 10 ml of THF was added. The mixture was stirred for 30 minutes at room temperature and 90 minutes at the reflux temperature of the reaction mixture, then cooled to room temperature and quenched with water. The organic layer was separated and the aqueous layer extracted twice with diethyl ether. The organic extracts were combined, dried over anhydrous magnesium sulfate, filtered and concentrated under vacuum. High pressure liquid chromatography of the residue afforded 3.58 g of ethyl 4-cyanomethylidene-N-t-butoxycarbonyl-2-piperidinecarboxylate. The mixture was stirred for 30 minutes at room temperature and 90 minutes at the reflux temperature of the reaction mixture cooled to room temperature quenched with water The organic layer was separated the aqueous layer extracted twice with diethyl ether dried over anhydrous magnesium sulfate filtered concentrated under vacuum

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

Procedure: To a 1 l. 138 round bottom flask was added 33.6 g (0.16 mol) of pyridinium chlorochromate, 35 g of powdered 4A molecular sieves and 200 ml of methylene chloride. After stirring the mixture at room temperature for sixty minutes, a solution of 21.3 g (0.078 mol) of ethyl cis-4-hydroxy-N-t-butoxycarbonyl-2-piperidinecarboxylate in 50 ml of methylene chloride was added. After stirring the mixture for sixty minutes at room temperature, 700 ml of diethyl ether was added. The mixture was filtered through three-fourths inch of Celite and three-fourths inch of silica gel (230-400 mesh) in a 650 ml medium porosity sintered glass funnel. The solids were washed with 1 1. of diethyl ether and the filtrate was concentrated under vacuum. To the residue was added 200 ml of diethyl ether and the mixture filtered through three-eighths inch of Celite and three-eighths inch of silica gel (230-400 mesh) in a 150 ml medium porosity sintered glass funnel. The solids were washed with 500 ml of diethyl ether and the filtrate was concentrated under vacuum. The residue was purified by high pressure liquid chromatography to provide 14.6 g of ethyl 4-oxo-N-t-butoxycarbonyl-2-piperidinecarboxylate as a colorless oil. After stirring the mixture for sixty minutes at room temperature The mixture was filtered through three-fourths inch of Celite and three-fourths inch of silica gel (230-400 mesh) in a 650 ml medium porosity sintered glass funnel The solids were washed with 1 1 of diethyl ether and the filtrate was concentrated under vacuum To the residue was added 200 ml of diethyl ether the mixture filtered through three-eighths inch of Celite and three-eighths inch of silica gel (230-400 mesh) in a 150 ml medium porosity sintered glass funnel The solids were washed with 500 ml of diethyl ether the filtrate was concentrated under vacuum The residue was purified by high pressure liquid chromatography