1H-Pyrazole-1-propanenitrile, β-cyclopentyl-4-[7-[[2-(triMethylsilyl)ethoxy]Methyl]-7H-pyrrolo[2,3-d]pyriMidin-4-yl]-, (βS)- synthesis

Yield:99.4 % ee ， 99.4 % ee

Reaction Conditions:

with 20-micron Chiralcel OD in hexane;isopropyl alcohol at 20;Purification / work up;Resolution of racemate;

Steps:

(3R)-Cyclopentyl-3-{4-[7-(2-trimethylsilanylethoxymethyl)-7H-pyrrolo [2,3-d]pyrimidin-4-yl]pyrazol-1-yl}propionitrile ((R)-10) and (3S)-Cyclopentyl-3-{4-[7-(2-trimethylsilanylethoxymethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]pyrazol-1-yl}propionitrile ((S)-10) A slurry of 1.5 Kg of 20-micron Chiralcel OD chiral stationary phase (CSP) made by Daicel in 3.0 L of isopropanol (IPA) was packed into a PROCHROM Dynamic Axial Compression Column LC110-1 (11 cm ID×25 cm L; Column Void Vol.: approximate 1.5 L) under 150 bar of packing pressure. The packed column was then installed on a Novasep Hipersep HPLC unit. The column and the Hipersep unit were flushed with methanol (17 L) followed by the mobile phase made of a mixture of isopropanol and hexane (2:8 by volume, 17 L). The feed solution was then prepared by dissolving 3-cyclopentyl-3-{4-[7-(2-trimethylsilanylethoxymethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]pyrazol-1-yl}propionitrile (9, racemic SEM-protected compound, 2795 g, 6.4 mol) in the mobile phase to a concentration of 80 g/L. The feed solution was then sequentially injected into the preparative chiral column for separation. Each injection was 120 ml in volume. The chiral column was eluted with the mobile phase at a flow rate of 570 mL/min at room temperature. The column elution was monitored by UV at a wavelength of 330 nm. Under these conditions a baseline separation of the two enantiomers was achieved. The retention times were 16.4 minutes (Peak 1, the undesired (S)-enantiomer (S)-10) and 21.0 minutes (Peak 2, the desired (R)-enantiomer (R)-10), respectively. The cycle time for each injection was 11 minutes and a total of 317 injections were performed for this separation process. Fractions for Peak 1 (the undesired (S)-enantiomer, (S)-10) and Peak 2 (the desired (R)-enantiomer, (R)-10) were collected separately from each injection. The collected fractions collected were continuously concentrated in the 1-square feet and 2-square feet ROTOTHERM evaporator, respectively, at 40° C. under reduced pressure (40-120 bar). The residue from each evaporator was further dried under high vacuum to constant weight to afford (3R)-cyclopentyl-3-{4-[7-(2-trimethylsilanylethoxymethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]pyrazol-1-yl}propionitrile ((R)-10, 1307 g, 1397.5 g theoretical, 93.5%) from Peak 2 as a light yellow oil and (3S)-cyclopentyl-3-{4-[7-(2-trimethylsilanylethoxymethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]pyrazol-1-yl}propionitrile ((S)-10, 1418 g, 1397.5 g theoretical, 101.5%) from Peak 1 as an yellow oil.; A chiral HPLC method was developed for chiral purity evaluation of both enantiomers of SEM-protected compound ((R)-10 and (S)-10) using a Chiralcel OD-H column (4.6×250 mm, 5 μm), purchased from Chiral Technologies, Inc., packed with silica gel coated with cellulose tris(3,5-dimethylphenyl carbamate) (Chiralcel OD). The two enantiomers of SEM-protected compound are separated with a resolution greater than 3.0 by using a mobile phase made of 10% ethanol and 90% hexanes at room temperature with a flow rate of 1 mL/min. The UV detection wavelength is 220 nm. The retention times for (S)-enantiomer ((S)-10) and (R)-enantiomer ((R)-10) are 10.3 minutes and 13.1 minutes, respectively.The quality of each enantiomer separated by preparative chiral HPLC including chemical purity (HPLC area % and wt %), chiral purity (chiral HPLC area %), and residual solvents (IPA and hexane) was analyzed and their structures are confirmed by NMRs and LC/MS. For (R)-10: achiral purity (99.0 area % by HPLC detected at 220 nm; 100.1 wt % by HPLC weight percent assay); chiral purity (99.7 area % by chiral HPLC; 99.4% ee); residual solvents (3.7 wt % for IPA; 0.01 wt % for hexane); ¹H NMR (DMSO-d₆, 400 MHz) δ ppm 8.83 (s, 1H), 8.75 (s, 1H), 8.39 (s, 1H), 7.77 (d, 1H, J=3.7 Hz), 7.09 (d, 1H, J=3.7 Hz), 5.63 (s, 2H), 4.53 (td, 1H, J=19.4, 4.0 Hz), 3.51 (t, 2H, J=8.1 Hz), 3.23 (dq, 2H, J=9.3, 4.3 Hz), 2.41 (m, 1H), 1.79 (m, 1H), 1.66-1.13 (m, 7H), 0.81 (t, 2H, J=8.2 Hz), 0.124 (s, 9H); C₂₃H₃₂N₆OSi (MW, 436.63), LCMS (EI) m/e 437 (M⁺+H) and 459 (M⁺+Na). For (S)-10: achiral purity (99.3 area % by HPLC detected at 220 nm; 99.9 wt % by HPLC weight percent assay); chiral purity (99.7 area % by chiral HPLC; 99.4% ee); residual solvents (4.0 wt % for IPA; 0.01 wt % for hexane); ¹H NMR (DMSO-d₆, 400 MHz) δ ppm 8.83 (s, 1H), 8.75 (s, 1H), 8.39 (s, 1H), 7.77 (d, 1H, J=3.7 Hz), 7.09 (d, 1H, J=3.7 Hz), 5.63 (s, 2H), 4.53 (td, 1H, J=19.4, 4.0 Hz), 3.51 (t, 2H, J=8.1 Hz), 3.23 (dq, 2H, J=9.3, 4.3 Hz), 2.41 (m, 1H), 1.79 (m, 1H), 1.66-1.13 (m, 7H), 0.81 (t, 2H, J=8.2 Hz), 0.124 (s, 9H); C₂₃H₃₂N₆OSi (MW, 436.63), LCMS (EI) m/e 437 (M⁺+H) and 459 (M⁺+Na).

References:

US2010/190981,2010,A1 Location in patent:Page/Page column 75-76