tert-butyl 4-(2-hydroxyethylidene)piperidine-1-carboxylate

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: To a solution of 15.292 g (67.277 mM) of tert-butyl 4-(2-hydroxyethylidene)piperidine-1-carboxylate and 24.5 g (74.0 mM) of carbon tetrabromide in 150 ml of acetonitrile was added 19.4 g (74.0 mM) of triphenylphosphine at −78° C. Then, at room temperature, the mixture was stirred for 2 hours. This reaction mixture was distilled under reduced pressure to remove the solvent. To the residue was added diethyl ether, followed by stirring, and the resulting precipitate was filtered off and washed with diethyl ether. The filtrate and washes were pooled and the solvent was distilled under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=30/1 to 9/1) to provide the title compound. This reaction mixture was distilled under reduced pressure to remove the solvent To the residue was added diethyl ether by stirring the resulting precipitate was filtered off washed with diethyl ether the solvent was distilled under reduced pressure The residue was purified by silica gel column chromatography (hexane/ethyl acetate=30/1 to 9/1)

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 19.901 g (73.888 mM) of tert-butyl 4-(ethoxycarbonylmethylene)piperidine-1-carboxylate in 100 ml of toluene was added 123 ml (185 mM) of 1.5 M diisobutylaluminum hydride-toluene at −78° C. and the mixture was stirred at −78° C. for 1 hour. Then, methanol was added at −78° C. and the mixture was stirred for 0.5 hour to decompose the excess diisobutylaluminum hydride. Then, water was added under ice-cooling and the mixture was stirred for 2 hours. The resulting precipitate was filtered off with the aid of celite and the celite was washed with ethyl acetate. The filtrate and washes were pooled and the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=3/1 to 1/1) to provide the title compound. the mixture was stirred for 0.5 hour cooling the mixture was stirred for 2 hours The resulting precipitate was filtered off with the aid of celite the celite was washed with ethyl acetate the solvent was distilled off under reduced pressure The residue was purified by silica gel column chromatography (hexane/ethyl acetate=3/1 to 1/1)

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

Procedure: To a solution of 4-(2-hydroxyethylidene)piperidine-1-carboxylic acid t-butyl ester (10.4 g, 46 mmol) in a mixture of hexane (300 mL)-chloroform (100 mL) was added manganese dioxide (100 g), and stirred for 10 hours. After the reaction was completed, insoluble materials were filtered off through Celite and the filtrate was concentrated under a reduced pressure to obtain 9.2 g (yield 89%) of 4-(2-oxoethylidene)piperidine-1-carboxylic acid t-butyl ester (VII-18, 20, 21, 24, 30, 41, 42, 43, 44, 45). insoluble materials were filtered off through Celite the filtrate was concentrated under a reduced pressure

Conditions: temp:0.00; pressure:0.00; stir: