Residual solution-phase concentration

A mixture of 26.1 g of o-benzylphenoxy- J-chloropropane and 17 g of pipiridine Is refluxed over a period of 32 hours until the temperature is about 124t and a nearly solid mixture is formed due to the precipitation of a salt. The mixture is then refluxed over a period of 48 hours at about 160 3 and the reaction product obtained is cooled and dissolved in methanol. The solution is concentrated under reduced pressure to yield an oil which is added to 200 ml 3N hydrochloric acid whereupon the mixture is shaken with ether, 3 x 100 ml, until the aqueous phase Is clear. The ether solution is washed with water, 3 x 50 ml, and the water present in the combined aqueous phase and water used for washing Is evaporated under reduced pressure methanol being added three times when the residue appears to be dry. The impure hydrochloride of o-benzylphenoxy- J-N-piperidinopropane, 41 g, obtained is dissolved in 100 ml water and 100 ml 30% aqueous sodium hydroxide solution are added, whereupon precipitated oil is extracted with ether, 1 x 100 and 2 x 50 ml. The ether solution is washed with water, 4 x 50 ml, dried with magnesium sulfate and the ether is removed under reduced pressure. The residue, 252 g, is distilled under reduced pressure and the main fraction,... 

The toluene phase was separated and discarded. The aqueous phase, together with a precipitated water- and toluene-insoluble oil, was made alkaline and extracted repeatedly with chloroform. The chloroform solution was concentrated in vacuo. The residue was re-... 

A mixture of rhodium II) acetate (228 mg, 0.516 mmol), the imidazolidinone (1.70 g, 6.15 mmol), and dry chlorobenzene (20 mL) is heated under reflux for 18 h in a flask fitted with a Soxhlet extraction apparatus into which a thimble is placed containing an oven-dried mixture of sodium carbonate and sand (2 1, 5 g). The progress of the ligand-exchange reaction can be monitored by HPLC (p-Bondapak-CN column, methanol). The resulting blue solution is concentrated under reduced pressure, and the residue is purified by column chromatography (reversed phase silica, Bakerbond Cyano 40 mm prep. LC packing, methanol). 

MeOH (0.122 mL, 3.0 mmol) was added dropwise to a stirred suspension of anhydride 57b (164 mg, 1.0 mmol) and quinidine (0.357 g, 1.1 mmol) in a mixture of toluene and tetra-chloromethane (1/1, 5 mL) at -55 °C under argon. The reaction mixture was stirred at this temperature for 60 h. During this period, the material gradually dissolved. Subsequently, the resulting clear solution was concentrated in vacuo to dryness, and the residue was dissolved in EtOAc. The solution was washed with 2N HCl and, after phase separation, followed by extraction of the aqueous phases with EtOAc the organic layer was dried (MgSO ), filtered and concentrated in vacuo to provide the corresponding hemiester (2//,35)-3-endo-methoxycarbonyl-bicyclo[2.2.1]hept-5-ene-2-endo-carboxylic acid as a white solid (192 mg, 98%, 99% ee by chiral-HPLC on the methyl 4-bromophenol diester). 

To fractionate a polymer by precipitation, a precipitant is slowly added to the polymer solution (concentration of polymer 0.1-1 wt%) at constant temperature until a persistent cloudiness appears. After some time the droplets separate as a second liquid (or swollen gel) phase. This fraction contains the highest molecular weight components and is separated by decantation or centrifugation. Further precipitant is then added to the majority layer until further phase separation is observed. Then the above procedure is repeated several times until all polymer is separated off. A disadvantage of fractional precipitation is that the residual solutions become more and more dilute so that separation of the late fractions might be difficult. Furthermore, the method is rather time consuming since the formation of the gel phase occurs very slowly. 

The distillation residue was slowly poured into 300 ml methanol and a precipitate formed. The precipitated material was isolated by filtering through a 0.5-p.m membrane filter and concentrated. The residue was dissolved in 200 ml hexane and then decolorized using activated carbon (5 g) and refiltered through the membrane filter. The solution was concentrated, dried under reduced pressure, and 47.09 g of product isolated having a gas-phase chromatography (GPC) purity of 99%. 

A stirred suspension of the adduct (1) (0.668g, 1.2 mmol) in dichloromethane (10ml) was treated with l-(trimethylsilyloxy)cyclooctene (0.198g, l.Ommol). After completion of the reaction (—20 min) the solution was concentrated in vacuo and the residue was partitioned between ether (50 ml) and water (15 ml). The organic phase was dried (MgS04) and concentrated in vacuo. The resulting solids were applied to a short column of silica gel (hexanes/ethyl acetate 7 3) to give 2-(phenylthio)cyclooctanone (0.20 g, 92%) as an oil. 

Procedure for BOC-amino acids. A solution of the amino acid (10 mol) in a mixture of dioxane (20 ml), water (10 ml) and 1 m sodium hydroxide (10 ml) is stirred and cooled in an ice-water bath. Di-t-butyl pyrocarbonate (1) (2.4 g, 11 mmol) is added and stirring is continued at room temperature for 30 minutes. The solution is concentrated in vacuo to about 10-15 ml, cooled in an ice-water bath, covered with a layer of ethyl acetate (30 ml) and acidified with dilute aqueous potassium hydrogen sulphate solution to pH 2-3 (Congo red). The aqueous phase is extracted with ethyl acetate (2 x 15 ml). The ethyl acetate extracts are pooled, washed with water (2 x 30 ml), dried over anhydrous sodium sulphate and evaporated in vacuo. The residue is recrystallised with a suitable solvent (e.g. ethyl acetate-hexane). 

An aldehyde was mixed with solid supported triphenylphosphine oxide (3 equiv.), alkyl halide (4 equiv.), and potassium carbonate (4 equiv.) in methanol (2 ml). The mixture was heated at 150° for 5 min. The residue was filtered through a short plug of silica gel and washed. The solution was concentrated and purified by reverse-phase high-performance liquid chromatography (RP-HPLC). 

Working up of the reaction mixture 25 ml of water are added dropwise with cooling, 20 ml of methylene chloride are then added, the organic phase is separated off, the aqueous phase is then extracted twice with 15 ml of methylene chloride each time, the combined organic phase is washed twice, in each case with 10 ml of water, dried with sodium sulfate, the solution is concentrated on a rotary evaporator, the residue is mixed with 10 ml of absolute ethanol and then reconcentrated. 

The alcoholic solution is concentrated to 1.2 L by evaporating in vacuo and shaken with an equal amount of ether. Dark coloring matters and residues of fat are thus dissolved. The aqueous phase is now mixed with acetone until a precipitate occurs and the dissolved in dilute acetic acid. The solution is brought to a weakly alkaline pH by addition of ammonia. It is then centrifuged and the inactivator is precipitated with five times the amount of ethanol. The yield amounts to about 180.000 kallikrein inactivator units in 0.4-0.5 g of substance. 

C) Preparation of 7-Chloro-2,3-Dihydro-l-Methyl-5-Phenyl-lH-l,4-Benzodiazepine A mixture of 4.7 g (22.6 mol) of 7-chloro-l,2,3,4-tetrahydro-l-methyl-5H-l,4-benzodiazepin-5-one and 100 ml of phosphorus oxychloride was heated in an oil bath at 100°C for 15 minutes. The solution was concentrated to dryness in vacuo. The residue was partitioned between methylene chloride and cold saturated sodium bicarbonate solution. The methylene chloride phase was dried over sodium sulfate and sodium bicarbonate, filtered, diluted with benzene and concentrated in vacuo to produce crude 5,7-dichloro-2,3-dihydro-l-methyl-lH- 1,4-benzodiazepine. 

To a solution of 5-methoxymethoxy-7-oxa-bicyclo[4.1.0]hept-3-ene-3-carboxylic acid methyl ester (4.9 g, 22.9 mmol) in 8/l-Me0H/H20 (175 ml, v/v) was added sodium azide (7.44 g, 114.5 mmol) and ammonium chloride (2.69 g, 50.4 mmol) and the mixture was refluxed for 15 h. The reaction was diluted with water (75 ml) to dissolve precipitated salts and the solution was concentrated to remove methanol. The resulting aqueous phase containing a precipitated oily residue was diluted to a volume of 200 ml with water and was extracted with ethyl acetate (3 times 100 ml). The combined organic extracts were washed with saturated NaCI (100 ml), dried (MgS04), filtered and evaporated. The crude was purified on silica gel (1/1-hexane/ethyl acetate) to afford 5-azido-4-hydroxy-3-methoxymethoxy-cyclohex-l-ene-l-carboxylic acid methyl ester (5.09 g, 86%) as a pale yellow oil. Subsequent preparations of 5-azido-4-hydroxy-3-methoxymethoxy-cyclohex-l-ene-l-carboxylic acid methyl ester provided material which was of sufficient purity to use in the next step without further purification. 

Difluoromethoxy-2-[(4,5-dimethoxy-2-pyridyl)methylthio]-lH-benzimidazole (about 1 g) are dissolved in 10 ml of dioxane and 2 ml of 1 N sodium hydroxide solution. An equimolar amount of a titrated aqueous sodium hypochlorite solution, to which 1 mole per liter of sodium hydroxide solution has been added, is first added dropwise, while cooling with ice. After one hour a further equivalent and after 3 hours half the equimolar amount of sodium hypochlorite are added, to achieve complete reaction. After a reaction time of 4 hours, 5 ml of 5% strength sodium thiosulfate solution and another 25 ml of dioxane are added and the upper dioxane phase is separated off, washed once with 5 ml of sodium thiosulfate solution and concentrated on a rotary evaporator. The oily residue is dissolved in 20 ml of water and 10 ml of ethyl acetate and the solution is brought to pH 7 with about 100 ml of a buffer solution of pH 6.8. The solid which has precipitated out is filtered off with suction over a suction filter, washed with water, extracted by stirring at OC with acetone and dried. 5-Difluoromethoxy-2-[(4,5-dimethoxy-2-pyridyl)methanesulfinyl]-lH-benzimidazole is prepared yield about 85%. 

In a flask there are charged sodium hydride titre 80% and benzene. Keeping temperature 20-30°C a solution of ethyl 4,4 -biphenylacetate and of crotyl bromide in dimethylformamide is dropped during 30 min in the flask. Then the reaction mixture is heated under reflux for 2 h, and subsequently cooled to 10°C. Thereafter H20 are charged and mixture stirred 15 min. Two phases separate. Organic phase is washed with H20 and dried. The dried solution is concentrated under vacuum till an oily residue consisting of ethyl ester of diphenesenic acid. 

---