Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.
Procedure: (R)-3-methylmorpholine (7.18 g, 71.01 mmol) and triethylamine (12.87 ml, 92.31 mmol) were added to methyl 2,4-dichloropyrimidine-6-carboxylate (14.70 g, 71.01 mmol) in DCM (100 ml). The resulting mixture was stirred at RT for 18 hours. Water (100 ml) was added, the layers separated and extracted with DCM (3×75 ml). The combined organics were dried over MgSO4, concentrated in vacuo and the residue triturated with Et2O to yield (R)-methyl 2-chloro-6-(3-methylmorpholino)pyrimidine-4-carboxylate (14.77 g, 77%); 1H NMR (400 MHz, CDCl3) 1.35 (3H, d), 3.34 (1H, td), 3.55 (1H, td), 3.70 (1H, dd), 3.81 (1H, d), 3.97 (3H, s), 4.03 (1H, dd), 4.12 (1H, br s), 4.37 (1H, br s), 7.15 (1H, s); m/z: (ESI+) MH+, 272.43. The liquors were concentrated onto silica and purified by chromatography on silica eluting with a gradient of 20 to 40% EtOAc in isohexane. Fractions containing product were combined and evaporated to afford (R)-methyl 2-chloro-6-(3-methylmorpholino)pyrimidine-4-carboxylate (1.659 g, 9%); 1H NMR (400 MHz, CDCl3) 1.35 (3H, d), 3.33 (1H, td), 3.55 (1H, td), 3.69 (1H, dd), 3.80 (1H, d), 3.97 (3H, s), 4.03 (1H, dd), 4.12 (1H, br s), 4.36 (1H, br s), 7.15 (1H, s); m/z: (ESI+) MH+, 272.43. b) Lithium borohydride, 2M in THF (18 ml, 36.00 mmol) was added dropwise to (R)-methyl 2-chloro-6-(3-methylmorpholino)pyrimidine-4-carboxylate (16.28 g, 59.92 mmol) in THF (200 ml) at 0° C. over a period of 20 minutes under nitrogen. The resulting solution was stirred at 0° C. for 30 minutes and then allowed to warm to RT and stirred for a further 18 hours. Water (200 ml) was added and the THF evaporated. The aqueous layer was extracted with EtOAc (2×100 ml) and the organic phases combined, dried over MgSO4 and then evaporated to afford (R)-(2-chloro-6-(3-methylmorpholino)pyrimidin-4-yl)methanol (14.54 g, 100%) which was used in the next step without purification; 1H NMR (400 MHz, CDCl3) 1.32 (3H, d), 2.65 (1H, br s), 3.25-3.32 (1H, m), 3.51-3.57 (1H, m), 3.67-3.70 (1H, m), 3.78 (1H, d), 3.98-4.09 (2H, m), 4.32 (1H, br s), 4.59 (2H, s), 6.44 (1H, s); m/z: (ESI+) MH+, 244.40. c) Methanesulfonyl chloride (4.62 ml, 59.67 mmol) was added dropwise to (R)-(2-chloro-6-(3-methylmorpholino)pyrimidin-4-yl)methanol (14.54 g, 59.67 mmol) and triethylamine (8.32 ml, 59.67 mmol) in DCM (250 ml) at 25° C. over a period of 5 minutes. The resulting solution was stirred at 25° C. for 90 minutes. The reaction mixture was quenched with water (100 ml) and extracted with DCM (2×100 ml). The organic phases were combined, dried over MgSO4, filtered and evaporated to afford (R)-(2-chloro-6-(3-methylmorpholino)pyrimidin-4-yl)methyl methanesulfonate (20.14 g, 105%) which was used in the next step without further purification; 1H NMR (400 MHz, CDCl3) 1.33 (3H, d), 3.13 (3H, s), 3.27-3.34 (1H, m), 3.51-3.57 (1H, m), 3.66-3.70 (1H, m), 3.79 (1H, d), 3.99-4.03 (2H, m), 4.34 (1H, br s), 5.09 (2H, d), 6.52 (1H, s); m/z: (ESI+) MH+, 322.83. Alternatively, this step can be carried out as follows: In a 3 L fixed reaction vessel with a Huber 360 heater/chiller attached, under a nitrogen atmosphere, triethylamine (0.120 L, 858.88 mmol) was added in one go to a stirred solution of (R)-(2-chloro-6-(3-methylmorpholino)pyrimidin-4-yl)methanol (161 g, 660.68 mmol) in DCM (7.5vol) (1.2 L) at 20° C. (3° C. exotherm seen). The mixture was cooled to 5° C. and then methanesulfonyl chloride (0.062 L, 792.81 mmol) was added dropwise over 15 minutes, not allowing the internal temperature to exceed 15° C. The reaction mixture was stirred at 15° C. for 2 hours and then held (not stirring) overnight at RT under a nitrogen atmosphere. Water (1.6 L, 10 vol) was added and the aqueous layer was separated and then extracted with DCM (2×1.6 L, 2×10 vol). The organics were combined, washed with 50% brine/water (1.6 L, 10 vol), dried over magnesium sulphate, filtered and then evaporated to afford a mixture of approximately two thirds (R)-(2-chloro-6-(3-methylmorpholino)pyrimidin-4-yl)methyl methanesulfonate and one third (R)-4-(2-chloro-6-(chloromethyl)pyrimidin-4-yl)-3-methylmorpholine (216 g) which was used in the next step without further purification. d) Lithium iodide (17.57 g, 131.27 mmol) was added to (R)-(2-chloro-6-(3-methylmorpholino)pyrimidin-4-yl)methyl methanesulfonate (19.2 g, 59.67 mmol) in dioxane (300 ml) and heated to 100° C. for 2 hours under nitrogen. The reaction mixture was quenched with water (200 ml) and extracted with EtOAc (3×200 ml). The organic layers were combined and washed with 2M sodium bisulfite solution (400 ml), water (400 ml), brine (400 ml) dried over MgSO4 and then evaporated. The residue was triturated with Et2O to afford (R)-4-(2-chloro-6-(iodomethyl)pyrimidin-4-yl)-3-methylmorpholine (13.89 g, 66%); 1H NMR (400 MHz, CDCl3) 1.32 (3H, d), 3.28 (1H, td), 3.54 (1H, td), 3.69 (1H, dd), 3.78 (1H, d), 3.98-4.02 (2H, m), 4.21 (2H, s), 4.29 (1H, br s), 6.41 (1H, s); m/z: (ESI+) MH+, 354.31. The mother liquors were concentrated down and triturated with Et2O to afford a further crop of (R)-4-(2-chloro-6-(iodomethyl)pyrimidin-4-yl)-3-methylmorpholine (2.46 g, 12%); 1H NMR (400 MHz, CDCl3) 1.32 (3H, d), 3.28 (1H, td), 3.54 (1H, td), 3.69 (1H, dd), 3.78 (1H, d), 3.98-4.02 (2H, m), 4.21 (2H, s), 4.30 (1H, s), 6.41 (1H, s); m/z: (ESI+) MH+, 354.31. Alternatively, this step can be carried out as follows: (R)-(2-Chloro-6-(3-methylmorpholino)pyrimidin-4-yl)methyl methanesulfonate (80 g, 248.62 mmol) and lithium iodide (83 g, 621.54 mmol) were dissolved in dioxane (300 ml) and then heated at 107° C. for 1 hour. The reaction mixture was quenched with water (250 ml), extracted with EtOAc (3×250 ml), the organic layer was dried over MgSO4, filtered and evaporated. The residue was dissolved in DCM and Et2O was added, the mixture was passed through silica (4 inches) and eluted with Et2O. Fractions containing product were evaporated and the residue was then triturated with Et2O to give a solid which was collected by filtration and dried under vacuum to afford (R)-4-(2-chloro-6-(iodomethyl)pyrimidin-4-yl)-3-methylmorpholine (75 g, 86%); m/z: (ESI+) MH+, 354.27. e) (R)-4-(2-Chloro-6-(iodomethyl)pyrimidin-4-yl)-3-methylmorpholine (17.0 g, 48.08 mmol) was dissolved in DMF (150 ml), to this was added sodium methanethiolate (3.37 g, 48.08 mmol) and the reaction was stirred for 1 hour at 25° C. The reaction mixture was quenched with water (50 ml) and then extracted with Et2O (3×50 ml). The organic layer was dried over MgSO4, filtered and then evaporated. The residue was purified by flash chromatography on silica, eluting with a gradient of 50 to 100% EtOAc in iso-hexane. Pure fractions were evaporated to afford (R)-4-(2-chloro-6-(methylthiomethyl)pyrimidin-4-yl)-3-methylmorpholine (12.63 g, 96%); m/z: (ES+) MH+, 274.35. Alternatively, (R)-4-(2-chloro-6-(methylthiomethyl)pyrimidin-4-yl)-3-methylmorpholine, may be prepared as follows: In a 3 L fixed vessel, sodium thiomethoxide (21% in water) (216 g, 646.69 mmol) was added dropwise over 5 minutes to a stirred solution of a mixture of approximately two thirds (R)-(2-chloro-6-(3-methylmorpholino)pyrimidin-4-yl)methyl methanesulfonate and one third (R)-4-(2-chloro-6-(chloromethyl)pyrimidin-4-yl)-3-methylmorpholine (130.2 g, 431 mmol) and sodium iodide (1.762 ml, 43.11 mmol) in MeCN (1 L) at RT (temperature dropped from 20° C. to 18° C. over the addition and then in the next 5 minutes rose to 30° C.). The reaction mixture was stirred for 16 hours and then diluted with EtOAc (2 L), and washed sequentially with water (750 ml) and saturated brine (1 L). The organic layer was dried over MgSO4, filtered and then evaporated to afford (R)-4-(2-chloro-6-(methylthiomethyl)pyrimidin-4-yl)-3-methylmorpholine (108 g, 91%); 1H NMR (400 MHz, DMSO-d6) 1.20 (3H, d), 2.07 (3H, s), 3.11-3.26 (1H, m), 3.44 (1H, td), 3.53 (2H, s), 3.59 (1H, dd), 3.71 (1H, d), 3.92 (1H, dd), 3.92-4.04 (1H, br s), 4.33 (1H, s), 6.77 (1H, s); m/z: (ES+) MH+, 274.36. f) (R)-4-(2-Chloro-6-(methylthiomethyl)pyrimidin-4-yl)-3-methylmorpholine (12.63 g, 46.13 mmol) was dissolved in DCM (100 ml), to this was added mCPBA (7.96 g, 46.13 mmol) in one portion and the reaction mixture was stirred for 10 minutes at 25° C. An additional portion of mCPBA (0.180 g) was added. The reaction mixture was quenched with saturated Na2CO3 solution (50 ml) and extracted with DCM (3×50 ml). The organic layer was dried over MgSO4, filtered and then evaporated. The residue was dissolved in DCM (80 ml) in a 150 ml conical flask which was placed into a beaker containing Et2O (200 ml) and the system covered with laboratory film and then left for 3 days. The obtained crystals were filtered, crushed and sonicated with Et2O. The crystallisation procedure was repeated to afford (R)-4-(2-chloro-6-((R)-methylsulfinylmethyl)pyrimidin-4-yl)-3-methylmorpholine as white needles (3.87 g, 29%); 1H NMR (400 MHz, CDCl3) 1.33 (3H, d), 2.62 (3H, s), 3.30 (1H, td), 3.53 (1H, td), 3.68 (1H, dd), 3.76 (2H, dd), 3.95 (1H, d), 4.00 (1H, dd), 4.02 (1H, s), 4.32 (1H, s), 6.42 (1H, s). The remaining liquor from the first vapour diffusion was purified by flash chromatography on silica, eluting with a gradient of 0 to 5% MeOH in DCM. Pure fractions were evaporated to afford (R)-4-(2-chloro-6-((S)-methylsulfinylmethyl)pyrimidin-4-yl)-3-methylmorpholine as an orange gum (5.70 g, 43%); 1H NMR (400 MHz, CDCl3) 1.33 (3H, d), 2.62 (3H, d), 3.29 (1H, td), 3.54 (1H, td), 3.68 (1H, dd), 3.73-3.82 (2H, m), 3.94 (1H, dd), 4.00 (2H, dd), 4.33 (1H, s), 6.42 (1H, s). Alternatively, this step can be carried out as follows: Sodium meta-periodate (64.7 g, 302.69 mmol) was added in one portion to (R)-4-(2-chloro-6-(methylthiomethyl)pyrimidin-4-yl)-3-methylmorpholine (82.87 g, 302.69 mmol) in water (500 ml), EtOAc (1000 ml) and MeOH (500 ml). The resulting solution was stirred at 20° C. for 16 hours. Sodium metabisulfite (50 g) was added and the mixture stirred for 30 minutes. The reaction mixture was filtered and then partially evaporated to remove the MeOH. The organic layer was separated, dried over MgSO4, filtered and then evaporated. The aqueous layer was washed with DCM (3×500 ml). The organic layers were combined, dried over MgSO4, filtered and then evaporated. The residues were combined and dissolved in DCM (400 ml) and purified by flash chromatography on silica, eluting with a gradient of 0 to 5% MeOH in DCM. Fractions containing product were evaporated and the residue was dissolved in DCM (400 ml) and then divided into four 450 ml bottles. An aluminium foil cap was placed over the top of each bottle and a few holes made in each cap. The bottles were placed in pairs in a large dish containing Et2O (1000 ml), and then covered and sealed with a second glass dish and left for 11 days. The resultant white needles were collected by filtration and dried under vacuum. The crystals were dissolved in DCM (200 ml) and placed into a 450 ml bottle. An aluminium foil cap was placed over the top of the bottle and a few holes made in the cap. The bottle was placed in a large dish containing Et2O (1500 ml) and then covered and sealed with a second glass dish and left for 6 days. The resultant crystals were collected by filtration and dried under vacuum to afford (R)-4-(2-chloro-6-((R)-methylsulfinylmethyl)pyrimidin-4-yl)-3-methylmorpholine (16.53 g, 19%); 1H NMR (400 MHz, CDCl3) 1.33 (3H, d), 2.61 (3H, s), 3.29 (1H, td), 3.53 (1H, td), 3.68 (1H, dd), 3.76 (2H, dd), 3.95 (1H, d), 3.99 (1H, dd), 4.02 (1H, s), 4.31 (1H, s), 6.41 (1H, s). Chiral HPLC: (HP1100 System 5, 20 μm Chiralpak AD-H (250 mm×4.6 mm) column eluting with Hexane/EtOH/TEA 50/50/0.1) Rf, 12.192 98.2%. The filtrate from the first vapour diffusion was concentrated in vacuo to afford an approximate 5:2 mixture of (R)-4-(2-chloro-6-((S)-methylsulfinylmethyl)pyrimidin-4-yl)-3-methylmorpholine and (R)-4-(2-chloro-6-((R)-methylsulfinylmethyl)pyrimidin-4-yl)-3-methylmorpholine (54.7 g, 62%). Alternatively, this step can be carried out as follows: Sodium meta-period
Source ID: ord-d8312f570553496eb3ba1581b2ba3961