methyl (2S)-2-amino-3-phenylpropanoate

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

Procedure: An enzymatic method for producing N-formyl-α-L-aspartyl-L-phenylalanine methyl ester by a condensation reaction between N-formyl-L-aspartic acid and L-phenylalanine methyl ester or D,L-phenylalanine methyl ester, which comprises: supplying an organic phase comprising a water-immiscible solvent containing N-formyl-L-aspartic acid and L- or D,L-phenylalanine methyl ester onto an aqueous phase comprising a thermolysin-like metalloprotease; proceeding the condensation reaction in the aqueous phase to produce N-formyl-α-L-aspartyl-L-phenylalanine methyl ester; and extracting the N-formyl-α-L-aspartyl-L-phenylalanine methyl ester thus produced from the aqueous phase to the organic phase. the condensation reaction in the aqueous phase

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

Procedure: Hydrochloride salt of (2S,5S)-5-benzyl-2-tert-butyl-3-methyllimidazolidin-4-one (1): To a solution of ethanolic MeNH2 (8.0 M, 50 ml) was added (S)-phenylalanine methyl ester (23.0 g, 130 mmol). The resulting solution was stirred at room temperature until the amino ester was judged to be consumed by TLC analysis. The resulting solution was then concentrated to provide (S)-phenylalanine N-methyl amide (18 g, 82% yield) as a white solid. To a flask containing (S)-phenylalanine N-methyl amide (8.9 g, 50 mmol) was added THF (100 ml), trimethylacetaldehyde (5.4 g, 50 mmol), FeCl3 (1.7 g, 10 mmol) and 4Å MS (5.0 g). The resulting mixture was stirred at room temperature for 36 h, then washed with H2O (3×100 mL). The combined organics were concentrated and the resulting residue was treated with HCl (27 mL, 1N in ether). The resulting heterogeneous mixture was filtered to removed the undesired trans isomer.HCl salt and the resulting solution was concentrated. The residue was recrystallized (9:1 pentane/CH2Cl2) to provide the product (1) as a crystalline solid (2.88 g, 23% yield, >99% ee). IR (film) 3343, 2958, 1605, 1028 cm−1; 1H NMR (300 MHz, CDCl3) δ7.31−7.17 (m, 5H, ArH), 4.04 (s, 1H, NCHN), 3.72−3.65 (m, 1H, CHCH2), 3.13 (dd, J=4.1, 13.7 Hz, 1H, CH2), 2.92 (dd, J=7.7, 13.7 Hz, 1H, CH2), 2.90 (s, 3H, NCH3), 0.82 (s, 9H, C(CH3)3); 13C NMR (75 MHz, CDCl3) δ175.3, 138.0, 129.8, 128.7, 126.8, 82.7, 77.8, 77.4, 76.9, 59.7, 38.6, 35.4, 31.0, 25.7; [α]D=−39.6 (c=1.0, CHCl3). The enantiomeric ratio was determined by HPLC using a Chiralpak OD-H and OD guard column (3.0% i-PrOH/hexanes, 1 mL/min); (5S) isomer tr=16.7 min, (5R) isomer tr=20.1 min. to be consumed by TLC analysis The resulting solution was then concentrated

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

Procedure: Sodium cyanoborohydride (1.1 g) and acetic acid (0.75 mL) were added to a mixture of methyl (S)-2-amino-3-phenylpropanoate (2.72 g) and (R)-tert-butyl 1-oxopropan-2-ylcarbamate (1.97 g) in methanol to perform reductive amination (2.37 g, 46%). Next, deprotection and conversion to hydrochloride were performed (1.0 g, 45%) using trifluoroacetic acid and a 4 M hydrochloric acid-1,4-dioxane solution, followed by subjecting to condensation with isoquinoline-6-sulfonyl chloride prepared in Reference Example 1 (1.04 g, 75%). 28 mg of the title compound was obtained as a white solid (29%) with reference to the method of Step 3 of Example 1 using 80 mg of the obtained product.

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

Procedure: A suspension consisting of 10.8 g. of L-phenylalanine methyl ester hydrochloride, 200 ml. of ethyl acetate and 100 ml. of water is neutralized by the addition of 4.6 g. of sodium bicarbonate. The ethyl acetate layer is dried over anhydrous sodium sulfate, then concentrated to dryness under reduced pressure. The L-phenylalanine methyl ester thus obtained is dissolved in 100 ml. of ethyl acetate and 4.9 g. of L-aspartic acid anhydride hydrobromide is added at -50°C. with stirring. Stirring is continued for about 40 minutes, at the end of which time the reaction mixture is extracted with water. The aqueous layer is separated and the pH adjusted to 4.8 -5.0 by the addition of aqueous sodium carbonate. The aqueous solution is then extracted several times at 50°C. with n-butyl alcohol, which has been equilibrated with an aqueous sodium chloride solution, prepared by dissolution of 11.68 g. of sodium chloride in 1300 ml. of water. The alcohol extracts are combined, then concentrated to dryness under reduced pressure to afford the crude product. Recrystallization of that material from water affords L-α-aspartyl-L-phenylalanine methyl ester. The ethyl acetate layer is dried over anhydrous sodium sulfate concentrated to dryness under reduced pressure

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

Procedure: reacting the resulting N-acetoacetyl-L-aspartic acid anhydride with L-phenylalanine methyl ester to form N-acetoacetyl-α-L-aspartyl-L-phenylalanine and

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

Procedure: Crude disodium N-acetoacetylaspartate, 28.51 parts, was stirred with 200 parts by volume of ethyl acetate and 11.7 parts by volume of acetic acid at 0°-5° C. under argon while 4.37 parts by volume of phosphorous trichloride was added dropwise. The resulting mixture was allowed to warm to ambient temperatures while stirring for 20 hours. To the resulting solution which contains N-acetoacetyl-L-aspartic anhydride was added dropwise over a 2 hour period 122 parts by volume of 0.9 M L-phenylalanine methyl ester in dioxane. After continued stirring for 20 hours, the solvent was evaporated under vacuum at 35°-40° C. Toluene, 200 parts by volume, was added to the residue and the evaporation was repeated, giving crude N-acetoacetyl-L-aspartyl-L-phenylalanine methyl ester as a semi-solid yellow residue. was added dropwise to warm to ambient temperatures After continued stirring for 20 hours the solvent was evaporated under vacuum at 35°-40° C Toluene, 200 parts by volume, was added to the residue the evaporation

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

Procedure: reacting N-acetoacetyl-L-aspartic anhydride with L-phenylalanine methyl ester to form N-acetoacetyl-α-L-aspartyl-L-phenylalanine.

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

Procedure: This invention encompasses a method and intermediates for preparing a commercial sweetening agent, α-L-aspartyl-L-phenylalanine methyl ester. The process involves reacting L-aspartic acid with diketene to form N-acetoacetyl-L-aspartic acid which is converted to N-acetoacetyl-L-aspartic anhydride by reaction with acetic anhydride. N-acetoacetyl-L-aspartic anhydride is reacted with L-phenylalanine methyl ester to provide N-acetoacetyl-α-L-aspartyl-L-phenylalanine methyl ester which is converted to α-L-aspartyl-L-phenylalanine methyl ester by reaction with hydroxylamine hydrochloride.

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

Procedure: Following General Procedure A and using N-(L-alaninyl)-L-phenylalanine methyl ester (prepared by coupling N-BOC-L-alanine (Sigma) and L-phenylalanine methyl ester (Sigma) using General Procedure A, followed by removal of the BOC-group using General Procedure Y) and dec-4-enoic acid prepare from ethyl dec-4enoate (ICM) using General Procedure N), the title compound was prepared as a solid (mp =115.5-117.5° C.). The reaction was monitored by tlc (Rf=0.52 in 50% EtOAc/hexanes; 0.60 in 10% CH3OH/CH2Cl2) and the product was purified by flash chromatography using 10% CH3OH/CH2Cl2 as the eluent. prepared followed by removal of the BOC-group prepare from ethyl dec-4enoate (ICM)

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

Procedure: Following General Procedure A and using N-(L-alaninyl)-L-phenylalanine methyl ester (prepared by coupling N-BOC-L-alanine (Sigma) and L-phenylalanine methyl ester (Sigma) using General Procedure A, followed by removal of the BOC-group using General Procedure Y) and pent-4-enoic acid (Aldrich), the title compound was prepared as a solid (mp=125.5-126.5° C.). The reaction was monitored by tlc (Rf=0.32 in 50% EtOAc/hexanes; 0.51 in 10% CH3OH/CH2Cl2) and the product was purified by flash chromatography using 10% CH3OH/CH2Cl2 as the eluent. prepared followed by removal of the BOC-group the product was purified by flash chromatography

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

Procedure: 10.35 Parts of N-acetyl-D-phenylalanine is dissolved in 40 parts of methanol, then treated with 17.9 parts of DL-phenylalanine methyl ester. A precipitate forms immediately and a additional 60 parts of methanol is added. The mixture then is filtered and the solid remaining is washed with additional methanol and dried. Recrystallization from methanol affords the crystalline salt of N-acetyl-D-phenylalanine and L-phenylalanine methyl ester, melting at about 170°-172° and displaying an [α]D in 0.5% water of about -33.3°. The mixture then is filtered the solid remaining is washed with additional methanol dried Recrystallization from methanol

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

Procedure: 10.35 Parts of N-acetyl-D-phenylalanine is dissolved in 40 parts of methanol, then treated with 17.9 parts of DL-phenylalanine methyl ester. A precipitate forms immediately and a additional 60 parts of methanol is added. The mixture then is filtered and the solid remaining is washed with additional methanol and dried. Recrystallization from methanol affords the crystalline salt of N-acetyl-D-phenylalanine and L-phenylalanine methyl ester, melting at about 170°-172° and displaying an [α]D in 0.5% water of about -33.3°. The mixture then is filtered the solid remaining is washed with additional methanol dried Recrystallization from methanol