Synthetic method of enantiomerically pure 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid

Abstract

The present invention relates to a method for preparing enantiomerically pure compounds 1a and 1b of the following formula 1 from racemic compound 1 of the following formula 1. [formula 1] The compounds 1a and 1b of the above formula 1 respectively are important intermediates for a process for preparing the respective compounds 2a and 2b of the following formula 2, which are 2,2′-binaphthol-3-aldehyde derivatives. The following compounds 2a and 2b are useful for preparing enantiomerically pure amino acids. The present invention provides a method for preparing the above compounds 1a and 1b very conveniently and economically, and suitably for mass production. [formula 2]

Claims

1. A method for preparing a diastereomic salt of 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate comprising: forming a solution by dissolving racemic 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid in an organic solvent; adding a chiral 1-phenethylamine into the solution and reacting the chiral 1-phenethylamine with the racemic 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid to form a solid precipitant comprising a diastereomic salt of 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate and a supernatant; and separating the thus formed solid precipitant from the supernatant to recover the diastereomic salt of 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate.

2. The method according to claim 1, wherein the chiral 1-phenethylamine is (S)(−)-1-phenyl amine and the diastereomic salt of the 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate is (S)(−)-1-phenyl amine (S) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate.

3. The method according to claim 1, wherein the chiral 1-phenethylamine is (R)(+)-1-phenethylamine and the diastereomic salt of the 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate is (R)(+)-1-phenyl amine (R) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate.

4. A method for preparing a diastereomic salt of 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate comprising: forming a solution by dissolving racemic 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid in an organic solvent; adding a chiral 1-phenethylamine into the solution and reacting the chiral 1-phenethylamine with the racemic 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid to form a solid precipitant comprising a diastereomic salt of 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate and a supernatant; separating the thus formed solid precipitant from the supernatant to recover the diastereomic salt of 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate; and neutralizing a solution comprising the diastereomic salt 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate to form an enantiomeric ally pure 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid.

5. The method according to claim 4, wherein the diastereomic salt of 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate is neutralized using hydrochloric acid.

6. A method for preparing a diastereomic salt of 1-phenyl amine 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate comprising: forming a solution by dissolving racemic 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid in an organic solvent; adding (S)(−)-1-phenyl amine into the solution and reacting the (S)(−)-1-phenyl amine with the racemic 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid to form a solid precipitant comprising a diastereomic salt of (S)(−)-1-phenyl amine (S) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylateand a supernatant; separating the thus formed solid precipitant from the supernatant to recover the diastereomic salt of (S)(−)-1-phenyl amine (S) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate; and neutralizing a solution of the (S)(−)-1-phenyl amine (S) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate to form enantiomerically pure (S) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid.

7. The method according to claim 6, wherein the (S)(−)-1-phenyl amine (S) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate is neutralized using hydrochloric acid.

8. The method according to claim 7, further comprising neutralizing a solution of the (R)(+)-1-phenyl amine (S) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate to form enantiomerically pure (R) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid.

9. The method according to claim 8, wherein the (R)(+)-1-phenyl amine (R) 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylate is neutralized using hydrochloric acid.

Description

MODE FOR THE INVENTION

(1) The present invention provides an optical resolution method of racemic compound 1 of the formula 1.

(2) ##STR00004##

(3) As shown in the above reaction formula 1, diastereomeric salts are prepared by dissolving compound 1 in an appropriate solvent and reacting it with compound 3a. During this process, compound 4a, whose solubility is relatively low, is precipitated in the form of solid, and the precipitate is filtered and separated to prepare salt 4a (>95% ee) of the optically resolved compound 1a. Methyl isobutyl ketone, acetonitrile, toluene, etc. are suitable as the solvents used in the reaction of compound 1 with compound 3a, which may be used alone or as a mixture thereof. A mixture solvent of methyl isobutyl ketone and acetonitrile would be preferable.

(4) ##STR00005##

(5) Further, salt 5a of the optically resolved compound 1b can be prepared from the compound 4b (>60% ee) solution of the above reaction formula 1. As shown in the above reaction formula 2, compound 5a, whose solubility is relatively low, is precipitated in the form of solid by washing the compound 4b solution with aqueous hydrochloric acid and reacting it with compound 3b, and then, the precipitate is filtered and separated to prepare salt 5a (>95% ee) of the optically resolved compound 1b.

(6) In addition, if chiral amine 3b is used in reaction formula 1, instead of chiral amine 3a, salt 5a (>95% ee) of the optically resolved compound 1b which is separated in the form of solid can be prepared. Then, if the filtrate is reacted with chiral amine 3a using the method of reaction formula 2, salt 4a (>95% ee) of the optically resolved compound 1a which is separated in the form of solid can be prepared.

(7) Thus, the present invention may use chiral amine 3a or 3b alone or may use chiral amines 3a and 3b successively in optical resolution, and in the case of using them successively, the reaction order is not limited.

(8) In addition, the present invention provides a method for preparing enantiomerically pure compound 1a or 1b, respectively by neutralizing compound 4a or 5a with aqueous hydrochloric acid and increasing optical purity.

(9) ##STR00006##

(10) As shown in the above reaction formula 3, the compound 4a (>95% ee) (or 5a) is dissolved in a suitable solvent and washed with aqueous hydrochloric acid to remove phenethylamine 3a (or 3b) that was used in optical resolution. After removing the solvent by concentrating the organic layers, they are dissolved in methanol, and the precipitated racemic compound is filtered and removed, and then, the solid that is precipitated by adding water is filtered to prepare enantiomerically pure compound 1a (>99% ee) (or 1b). Any solvent can be used as an organic solvent for the step of washing with aqueous hydrochloric acid as long as the solvent is not miscible with water and can dissolve compound 1a (or 1b). Methyl isobutyl ketone (MIBK), methyl t-butyl ether (MTBE), methylene chloride, ethyl acetate, etc. would be preferable.

(11) Below, the present invention is explained in detail using examples. However, the following examples are only for exemplifying the present invention, and the present invention is not limited by the following examples.

EXAMPLES

Example 1

Preparation of Salt of (S)-2,2′-Dihydroxy-1,1′-Binaphthyl-3-Carboxylic Acid(S)(+1-Phenethylamine (Compound 4a)

(12) After dissolving racemic 2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid (compound 1) (30.0 g, 90.8 mmol) which is prepared by applying and improving a known method [M. Noji, M. Nakajima and K. Koga. Tetrahedron Lett. 35 (1994), p. 7983-7984] in 330 mL of MIBK/acetonitrile (10/1, v/v), (S)(−)-1-phenethylamine (compound 3a) (5.50 g, 45.4 mmol) was added, and the mixture was stirred for two hours. After further adding compound 3a (2.75 g, 22.7 mmol) thereto, the mixture was stirred for two hours. Then, after further adding compound 3a (2.75 g, 22.7 mmol) thereto, the mixture was stirred for three hours. Thereafter, the precipitated solid was filtered to obtain 16.5 g of the subject compound 4a (36.5 mmol, 96.6% ee) at a yield of 80.4%.

(13) .sup.1H NMR (DMSO-d.sub.6, 400 MHz) δ8.47 (s, 1H, ArH), 7.93˜7.83 (m, 1H, ArH), 7.82 (d, 2H, ArH), 7.51 (d, 2H, ArH), 7.42 (t, 2H, ArH), 7.40˜7.30 (m, 2H, ArH), 7.23˜7.12 (m, 4H, ArH), 6.97 (d, 1H, ArH), 6.87 (d, 1H, ArH), 4.44 (q, 1H, CH), 1.53 (d, 3H, CH.sub.3).

(14) HPLC analysis condition (optical purity); analysis instrument: HPLC (Agilent 1200 series); column: Chiralcel OJ-RH (4.6×150 mm, Daicel), temperature (40° C.); solvent: 40% acetonitrile/H.sub.2O (0.1% H.sub.3PO4) (4/6, v/v), flow rate: 1.0 mL/min, detection wave length: 210 nm (or 230 nm).

(15) The filtrate was used for the preparation of salt of (R)-2,2-dihydroxy-1,1′-binaphthyl-3-carboxylic acid.Math.(R)(+)-1-phenethylamine (compound 5a) in the following Example 2.

Example 2

Preparation of a Salt of (R)-2,2′-Dihydroxy-1,1′-Binaphthyl-3-Carboxylic Acid.Math.(R)(+)-1-Phenethylamine (Compound 5a)

(16) After adding 6% of HCl solution (60 mL) to the filtrate of the above Example 1 and stirring the mixture for 30 minutes, organic layers were separated and washed with 3% of HCl (60 mL) and water (60 mL) sequentially. The organic layers were dried by anhydrous magnesium sulfate and filtered. Acetonitrile (30 mL) was added, (R)(+)-1-phenethylamine (compound 3b) (4.40 g, 36.3 mmol) was added, and the mixture was stirred for two hours. After further adding compound 3b (2.20 g, 18.2 mmol), the mixture was stirred for three hours. Thereafter, the precipitated solid was filtered to obtain 15.5 g of salt of (R)-2,2′-dihydroxy-1,1′-binaphthyl-3-carboxylic acid .Math.(R)(+)-1-phenethylamine (compound 5a) (34.3 mmol, 95.5% ee) at a yield of 75.6%.

(17) .sup.1H NMR (DMSO-d.sub.6, 400 MHz) δ8.47 (s, 1H, ArH), 7.93˜7.83 (m, 1H, ArH), 7.82 (d, 2H, ArH), 7.51 (d, 2H, ArH), 7.42 (t, 2H, ArH), 7.40˜7.30 (m, 2H, ArH), 7.23˜7.12 (m, 4H, ArH), 6.97 (d, 1H, ArH), 6.87 (d, 1H, ArH), 4.44 (q, 1H, CH), 1.53 (d, 3H, CH.sub.3).

Example 3

Preparation of (S)-2,2′-Dihydroxy-1,1′-Binaphthyl-3-Carboxylic Acid (Compound 1a)

(18) Compound 4a (15.0 g, 33.2 mmol, 96.6% ee) was added to methyl t-butyl ether (MTBE) (120 mL), and while stiring the mixture, 6% of aqueous hydrochloric acid (60 mL) was added thereto. After stirring the mixture for one hour at room temperature and separating layers, the organic layers were washed with water (60 mL). The organic layers were concentrated under reduced pressure, methanol (60 mL) was added thereto, and the mixture was stirred for one hour. The precipitated solid was filtered and removed. The filtrate was slowly added to water (120 mL). The precipitated solid was filtered and dried at 80° C. to obtain the subject compound 1a (10.2 g, 30.9 mmol, 99.1% ee) at a yield of 93%.

(19) .sup.1H NMR (DMSO-d.sub.6, 400 MHz) δ11.09 (s, 1H, OH), 9.17 (s, 1H, OH), 8.72 (s, 1H, ArH), 8.08-8.03 (m, 1H, ArH), 7.86 (t, 2H, ArH), 7.37˜7.28 (m, 3H, ArH), 7.26˜7.15 (m, 2H, ArH), 6.99˜6.91 (m, 2H, ArH).

Example 4

Preparation of (R)-2,2′-Dihydroxy-1,1′-Binaphthyl-3-Carboxylic Acid (Compound 1b)

(20) The subject compound 1b (10.3 g, 31.2 mmol, 99.0% ee) was obtained at a yield of 91% using compound 5a (15.5 g, 34.3 mmol, 95.5% ee) by the same method as in the Example 3 above.

(21) .sup.1H NMR (DMSO-d.sub.6, 400 MHz) δ11.10 (s, 1H, OH), 9.27 (s, 1H, OH), 8.70 (s, 1H, ArH), 8.08˜8.04 (m, 1H, ArH), 7.86 (t, 2H, ArH), 7.35˜7.30 (m, 3H, ArH), 7.26˜7.15 (m, 2H, ArH), 6.98˜6.91 (m, 2H, ArH).