D-Camphor-10-sulfonic acid

Derivatization of chiral arylalkylamines and NMR measurement of the diastereomeric ratios can be conveniently performed using d-camphor-10-sulfonic acid, having the (l/ ,4/ ) configuration49. 

Dimethyl-l-(aryl)pyrimidine-2(l//)-(thio)ones (134a-d) were resolved into enantiomers with D-camphor-10-sulfonic acid and their barriers to racemization determined by polarimetry (80JCS(P1)1599). These barriers deserve comment, since their trend is opposite to what is expected (Scheme 98). 

Hydroxybutylation of hydroquinones,1 Reaction of hydroquinones with 1 in the presence of D-camphor-10-sulfonic acid gives monotetrafuryl ethers (2), which rearrange to 2-tetrahydrofurylhydroquinones (3) in the presence of additional amounts of the acid... 

ACIDS, ORGANIC Acetyl sulfuric acid. d-(+)-Camphor-10-sulfonic acid. Formic acid. Methanesulfonic acid. Picric acid. p-Tolucnesulfonic acid. Trichloroacetic acid. Trifluoroacetic acid. Trifluorometh-ancsulfonic acid. 

Many organosulfur compounds can be resolved into optically active forms (enantiomers) owing to the presence of a chiral (asymmetric) sulfur atom 5 important examples include sulfoxides and sulfonium salts. Chiral sulfoxides containing amino or carboxylic acid groups have been resolved by formation of the diastereoisomeric salts with d-camphor-10-sulfonic acid or d-brucine. The salts can then be separated by fractional crystallisation and the free optically isomeric sulfoxides liberated by acid hydrolysis. However, a more convenient synthetic procedure for the preparation of chiral sulfoxides of high optical purity is Andersen s method (see p. 30). 

Camphorsulfonic acid D-Camphor-10-sulfonic acid Camphostyl Camsylate CSA EINECS 221-554-1 2-Oxobornane-10-sulphonic... 

Gotti et al. [42] reported an analytical study of penicillamine in pharmaceuticals by capillary zone electrophoresis. Dispersions of the drug (0.4 mg/mL for the determination of (/q-penicillaminc in water containing 0.03% of the internal standard, S -met hy I - r-cystei ne, were injected at 5 kPa for 10 seconds into the capillary (48.5 cm x 50 pm i.d., 40 cm to detector). Electrophoresis was carried out at 15 °C and 30 kV, with a pH 2.5 buffer of 50 mM potassium phosphate and detection at 200 rnn. Calibration graphs were linear for 0.2-0.6 pg/mL (detection limit = 90 pM). For a more sensitive determination of penicillamine, or for the separation of its enantiomers, a derivative was prepared. Solutions (0.5 mL, final concentration 20 pg/mL) in 10 mM phosphate buffer (pH 8) were mixed with 1 mL of methanolic 0.015% 1,1 -[ethylidenebis-(sulfonyl)]bis-benzene and, after 2 min, with 0.5 mL of pH 2.5 phosphate buffer. An internal standard (0.03% tryptophan, 0.15 mL) was added and aliquots were injected. With the same pH 2.5 buffer and detection at 220 nm, calibration graphs were linear for 9.3-37.2 pg/mL, with a detection limit of 2.5 pM. For the determination of small amounts of (L)-penicillamine impurity, the final analyte concentration was 75 pg/mL, the pH 2.5 buffer contained 5 mM beta-cyclodextrin and 30 mM (+)-camphor-10-sulfonic acid, with a voltage of 20 kV, and detection at 220 nm. Calibration graphs were linear for 0.5-2% of the toxic (L)-enantiomer, with a detection limit of 0.3%. 

The authors reported the chiral separation of proline and thereonine amino acid up to 20 and 6g, respectively, in a single run. Micropreparative resolution of lecucine was presented. The resolution was discussed with respect to the degree of sorbent saturation with copper(II), elution rate, eluent concentration, temperature, and column loading condition [16]. Weinstein [74] reported the micropreparative separation of alkylated amino acids on a Chiral ProCu column. In another article, a preparative chiral resolution of 3-methylene-7-benzylidene-bicyclo[3.3.1]nonane was achieved on 7.5% silver(I)-d-camphor- 10-sulfonate CSP [75]. Later, Shieh et al. [71] used L-proline-loaded silica gel for the chiral resolution of (ft,5 )-phcnylcthanolaminc as the Schiff base of 2-hydroxy-4-methoxyacetophenone. Gris et al. [76] presented the preparative separations of amino acids on Chirosolve L-proline and Chirosolve L-pipecolic acid CSPs. 

In a similar manner, D-camphor-lO-sulfonic acid (10-CSA) has heen used in the synthesis of 2-thiazolines. In the example shown in Scheme 82, endothiopeptide 208 was converted into thiazol-5(4//)-one 209 . 

Calcium carbonate as support for palladium catalyst, 46, 90 Calcium hydride, 46, 58 D,L-Camphor, sulfonation to d,l-10-camphorsulfonic acid, 46,12 10-Camphorchlorosulfoxide, 46, 56 d,l-10-Camphorsulfonic acid, 46,12 conversion to acid chloride, 45,14 10-Camphorsulfonyl chloride, 45, 56 d,l-10-Camphorsulfonyl chloride,... 

Sulfinic esters, aromatic, by oxidation of disulfides in alcohols, 46, 64 Sulfonation ot d,l camphor to d,l-10-camphorsulfomc acid, 45,12 Sulfoxides, table of examples of preparation from sulfides with sodium metapenodate, 46,79 Sulfur dioxide, reaction with styrene phosphorus pentachlonde to give styrylphosphomc diclilonde, 46,... 

Calcium carbonate as support for palladium catalyst, 46, 90 Calcium hydride, 46, 68 D,L-Camphor, sulfonation to d,l-10-camphorsulfonic acid, 46,12... 

The present method is adapted from that of Loven.1 The resolution has been carried out with d-a-bromocamphor-ir-sulfonic acid (Z-form) 2 3 with Z-and dZ-malic acids (d- and Z-forms) 4 with Z-quinic acid and d-tartaric acid (d- and Z-forms),5 and with d- and Z-6,6 -dinitrodiphenic acids (d- and Z-forms).6 Methods employing d-benzylmethylacetyl chloride,7 d-oxymeth-ylenecamphor,8 Z-quinic acid, and d-camphoric anhydride 10 are of theoretical interest only. The dZ-amine is not resolved by the active camphor-io-sulfonic acids 11 or mandelic acids.12... 

Circular Dichroism Measurements. Circular dichroism measurements were carried out by using a Cary model 6002 spectro-polarimeter calibrated with d-10 camphor sulfonic acid. All measurements were run at room temperature in the same 1 cm, quartz cell over the near-ultraviolet region (250-330 nm). 

Chen, G.C. and Yang, J.T. 1977. Two-point calibration of circulardichrometerwith D-10-camphor-sulfonic acid. Anal. Lett. 10 1195-1207. 

Mobile phase MeOH water glacial acetic acid 60 40 0.2 containing 5 mM D, L-10-sodium camphor sulfonate, adjusted to pH 6.0 (RI detection) or MeOH water 60 40 containing 10 mM phosphate buffer and 5 mM sodium pentanesulfonate, pH 6 (UV detection) Flowrate 1... 

The most familiar of the sulfonic adds derived from camphor is 10-camphorsulfonic add (44, Reychler s acid45). Both enantiomers are commercially available and convenient procedures exist for their preparation by sulfonation of camphor (ref 46 exemplifies the racemate, but the procedure works equally well for optically active camphor). The free acid is often applied to the resolution of basic compounds such as amines. A detailed review on the use of derivatives of this acid as auxiliaries has been given3. Esters of this add are normally obtained by the reaction of the alcohols with the sulfonyl chloride which is also commerdally available (or readily obtained by the reaction of the free acid with phosphorus pentachloride or thionyl chloride46,48). Such esters with unsaturated alcohols have been used for diastereoselective [1,2] sigma tropic rearrangements (Section D.1.6.3.3.). Allyl esters have been used for enantioselective alkylation reactions, in which camphorsulfonic acid reacts as the chiral leaving group (Section D.1.1.2.2.). 

---