Daicel columns

The enantiomeric excess of 3.10c has been determined by HPLC analysis using a Daicel Chiracel OD column and eluting with a 60 / 1 (v/v) hexane(HPLC-grade) / 2-propanol(p.a.) mixture. At a flow of 1 ml per minute the rentention times for the different isomers of 3.10c were 6.3 min. (exo, major enantiomer) 7.1 min. (exo, minor enantiomer) 7.7 min. (endo, major enantiomer) 10.7 min. (endo, minor enantiomer). 

DAICEL aiiiiouiicemeiit Daicel has announced an investment in a SMB production plant with columns of 100 mm i.d. to be installed in their facilities at Arai (Japan). This plant produces hundreds of kg per year for a drug currently manufactured by Nissan Chemicals (Japan Chemical Week, December 4, 1997). 

SUMICHIRAL OA-25001 is available from Sumitomo Chemical Co., Ltd. The eluent was hexane/1,2-dichloroethane/ethanol, 200 40 1, with a flow rate of 0.5 mL/min, and detection by 254 nm light. The tR of the (R)-isomer (16.8 min) is shorter than that of the (S)-isomer (18.3 min). The checkers used a CHIRACEL OC column supplied by Daicel Chemical Industries, Ltd., with 10% isopropyl alcohol/heptane as the mobile phase. 

CR y)-2-Amino-3-(3-hydroxy-l,2,5-thiadiazol-4-yl)propionic acid 42 was resolved into the (—)- and (+)-enantiomers using a semipreparative Crownpak CR(+)-column (150 x 10mm2) equipped with a Crownpak CR(+) guard column (10 x 4.0 mm2) (Daicel). The column was eluted at 0 °C (ice bath) with aqueous trifluoroacetic acid (TFA) (pH 2.0) at 1.5 mlmin-1. After removal of the acidic mobile phase, the pure enantiomers could be crystallized as zwitterions with high ee (99.9%) <2002BMC2259>. The first eluted (—)-enantiomer has the ////-configuration as proved by an X-ray crystallographic analysis. 

For experiments conducted in Liverpool GC was performed on a Shimadzu GC-14A gas chromatograph using a SE30 capillary column with the injector and detector set to 250 °C chiral GC was performed with chiral capillary columns (Lipodex E and C as indicated) with the injector and detector set to 250 °C. HPLC was performed on a Gilson chromatograph equipped with chiral columns Daicel Chiralpack AD and OD (wavelength 254 nm). 

HPLC with a Chiralcel OJ-H column (0.46 cm x 25 cm, Daicel industries) ice bucket and ice. 

All aldehydes used in the experiment were freshly distilled or washed with aqueous NaHC03 solution to minimize the amount of free acid. Chiral HPLC was performed using a chiral OJ-H column (0.46 cm x 25 cm, Daicel industries) with a water 717 auto sampler and a UV-vis detector (254 nm). The eluting solvent used was different ratios of hexane and 2-propanol. Chiral gas chromatography analysis was performed in a Shimadzu auto sampler with cyclodextrins columns as chiral stationary phase (fused-silica capillary column, 30 m X 0.25 mm x 0.25 gm thickness, /3-Dex-120 and /3-Dex-325 from Supelco, USA) using He as a carrier gas (detector temperature 230 °C and injection temperature 220 °C). 

Enantiomeric excess was determined by high-performance hquid chromatography with a Chiralpak WE column (4.6 mm x 250 mm, Daicel Chemical Industries, Tokyo), 2 him CUSO4, 0.75 ruL min, 50 °C, monitored at 254 nm L-pipecolic acid r = 14.7 min, D-pipecolic acid rt= 18.0 min. 

The column contained Daicel Chiralcel OD-H (eluent, hexane/2-propanol = 98/2). 

The enantiomeric purity is determined by chiral stationary phase, supercritical fluid chromatographic (CSP-SFC) analysis (Berger Instruments, Daicel Co. CHIRALCEL OD column 4% methanol, 180 psi, 3.0 mUmin flow rate detection at 220 nm). Racemic 1-phenylpropanol exhibited base-line separation of peaks of equal intensity arising from the R-isomer (tp, 2.74 min) and the S-isomer (tp, 3.10 min) whereas the synthetic alcohol showed these peaks in the ratio 97.7 / 2.3. This chromatographic method allowed for identification of the trace contaminants propiophenone (tp, 1.63 min) and benzyl alcohol (tp 3.40 min). 

The submitters used HPLC analysis to determine the enantiomeric purity (Daicel Co. CHIRALCEL OB column 99.5/0.5 hexane/2-propanol mixture, 1.0 mL/min flow rate detection at 254-nmS-isomer tp, 19.2 min, R-isomer tp 24.6 min)). Under these conditions, however, the propiophenone contaminant Is coincident with the S-enantiomer thus affording unreliable enantiomeric analysis. 

The ratio of the enantiomeric benzyl amide products was determined by analyzing a diluted aliquot of the quenched reaction mixture by HPLC using a chiral stationary phase column (Chiralcel OD, Daicel Chemical Co.). Since racemization is a pseudo-first-order kinetic process, these data (along with the time zero value) are sufficient for determination of the intrinsic rate of racemization kR. The half-life for racemization lRU2 can be directly calculated from the l/d ratio (or % enantiomeric excess, %ee) where t was the time of benzylamine addition (the delay time) ... 

Chiralcel Type CSP and Columns, Application Notes. Daicel Chemical Industries. Tokyo 1993. 

Crownpak1 Columns, Daicel Chemical Ind., Application Notes, Tokyo, Japan 1993. 

Chiralpak, Daicel Tokyo similar columns available from Serva, Heidelberg Machcrcy Nagel, Diiren 1992. 

Deprotonation of the 9-azabicyclo 3.3.11nonan-3-one derivative 1 with chiral lithium amides in tetrahdyrofuran at low temperatures in the presence of chlorotrimethylsilane (internal quench) gives the trimethylsilyl enol ether (lS,5/ )-2 in high yield with high enantiomeric excess. The absolute configuration and enantiomeric excess of 2 are based on chemical correlation and HPLC on a chiral Daicel OJ column, respectively38. The 2,2-dimethylpropyl- and 4-methyl-l-piperazinyl- substituted lithium amide is, as noted in other cases, superior. The bicyclic trimethylsilyl enol ether 2 serves as intermediate in the synthesis of piperidine alkaloids. 

Enantioselective reduction of prostereogenic anhydrides la-g with 4 equivalents of chiral reducing reagent, obtained from lithium aluminum hydride, enantiomerically pure (M)-, 1 -bi-2-naph-thol and ethanol, provides easier access to chiral lactones as exemplified by 3a-g.10 la. Absolute configurations of lactones 3 are based on chemical correlation and the ee value for 3b is determined by HPLC on the chiral column Chiralcel OB-H (Daicel Chemical Industries, Ltd.)101b. 

The concentrations of benzaldehyde, the mixed product, and benzoin and the enantiomeric excesses (revalues) were determined by chiral-phase HPLC with a photodiode array detector. Chiral-phase HPLC was performed on a Chiracel OD-H (Daicel, Diisseldorf, Germany) using isohexane/isopropanol (90 10) as eluent, a flow rate of 0.5 mL min and a column oven at 40 °C. The retention time for benzaldehyde was 10.2 min, for the mixed product DMA-HPP 15.1 and 16.4 min, for the (S)-benzoin 20.3 min, and for the (R)-benzoin 28.5 min. 

The enantiomeric excess was determined by HPLC analysis (column Daicel Chiralcel OD-H, eluent n-hexane/2-propanol 98/2, flow rate 0.5 mL min, detector UV 254 nm, retention time 32.4 and 34.3 min). Absolute configuration of the epoxy compound was (xR,pS), which was determined by comparison of HPLC data with the literature reference. " ... 

The mixture was extracted with diethyl ether (three times). The combined organic layers were washed with brine and dried over sodium sulfate. After concentration in vacuo, the residue was purified by silica gel flash column chromatography (hexane/ethyl acetate = 20/1-3/1) to give (5)-l (426.3 mg, 74%, 98% ee) as a colourless solid. The enantiomeric excess of (5)-l was determined by chiral stationary-phase HPLC analysis DAICEL CHIRALCEL OD-H, j-PrOH/hexane 1/4, flow rate l.OmLmin tR 14.0 min [(R)-isomer)] and 21.3 min [(5)-isomer), detection at 254 nm]. ... 

A crystalline powder of the 2 1 1 complex of (—)-l, 2 and CHC13 (4.44 g) was irradiated by a 400-W high-pressure Hg-lamp (Pyrex filter) in the solid state for 70 h. Separation of the reaction mixture by silica gel column chromatography gave a mixture of (-)-5-isopropyl-7-methoxybicyclo[3.2.0]hepta-3,6-dien-2-one 3 ([a]D-207° (c 0.23, CHC13), 96% ee) and (-)-methyl-l-isopropyl-4-oxocyclopent-2-ene-l-acetate 4 ([a]D-94.6 °(c 0.10, CHC13), 90% ee). The optical purities were determined by HPLC (Chiralcel OD, Daicel). 

The solid-state photoreaction of thioamide 1 was done under an atmosphere purged with dry argon. The solid sample was irradiated for 4 h as a powder prepared by grinding, and placed inside a Pyrex slide. When powdered thioamide 1 was irradiated in the solid state at 0 °C, at up to 19% conversion, optically active /i-thiolactam 2 of 31% ee was isolated. The optical purity was determined by HPLC using a chiral cell OD column (Daicel Chemical Ind.). 

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