3198-15-0

Separation of Enantiomers by Partition between Liquid Phases; Salts of enantiomeric α-aminoalcohols, such as norephedrin, with lipophilic anions, such as hexafluorophosphate ion, can be separated by partition between aqueous and lipophilic phase containing esters of tartaric acid.

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Disclosed herein is a process for the manufacture of (R)-phenylacetylcarbinol ((R)-PAC), (1R,2S). Ephedrine and its salts, (1R,2S)-norephedrine and its salts and 1-(Phenyl/Substituted phenyl)-2-(amino/alkylamino/dialklyamino) propan-1-ol and its salts, by enzymatic reduction of α-isonitrosopropiophenone (INP) and substituted α-isonitrosopropiophenone (substituted INP). The β-amino alcohols, produced by the process of present invention gives their corresponding diastereomers on Walden inversion. The present preparation process of (R)-PAC with (R)-PAC oxime as an intermediate has the advantage, that propiophenone as a key raw material which is easily available and has a low-price, operationally simple with high yield and a single process leading to the synthesis of several 1,2-aminoalcohol/ β- aminoalcohols active pharmaceutical ingredients. The design approach of the process is to reduce environmental impact of the product by comparing to the present manufacturing process.

An efficient route for the synthesis of 6 drugs belonging to phenethylamine and amphetamine classes in excellent overall yields and high optical purity has been described. The strategy involves introduction of stereogenic centers by means of two-stereocentered Co(III)-catalyzed hydrolytic kinetic resolution (HKR) of racemic syn-benzyloxy epoxide followed by Pd-catalyzed regioselective cationic hydrogenation of amino alcohols as the key reactions.

A method for the preparation of β-amino alcohol of formula (III) in which R1 is Ph, (substituted) Ph, R2 is C1-8 alkyl or C4-6 cyclo alkyl, R3 = R4R5CHNH2 where, R4 = H, C1-8 alkyl, C4-6 cyclo alkyl, or - COOR6 (R6=C1-C8 alkyl); R5 = (subst) aryl], the method including subjecting an α-hydroxy ketone of formula (I) in which R1 and R2 are as defined above is reacted with a chiral amine of formula R3NH2 where R3 = R4R5CH- where, R4 = H, C1-8 alkyl, C4-6 cycloalkyl, or - COOR6 (R6=C1-8 alkyl), R5 = (subst) aryl] to produce a compound of formula (II) in which R1, R2 and R3 are as defined above, followed by reduction to form the compound of formula (III).

In this article, a practically interesting route for the diastereoselective synthesis of phenylpropanolamines has been demonstrated for the first time. Using racemic O-tert-butyldiphenylsilyl (TBDPS) cyanohydrins as the starting materials, various syn phenylpropanolamines and derivatives (e.g., norpseudophedrine) have been successfully prepared in exellent diastereoselectivity via a practically interesting process.

The present invention provides a novel hydrogenation catalyst, process of preparing the catalyst and process for the preparation of optically active L-norephedrine, [(1R,2S)-2-amino-1-phenyl-1-propanol] by a catalytic hydrogenation process, said catalyst comprising of finely divided nickel metal containing a metal from group III A of the periodic table as an activator and a metal from group VI B or VIII as promoter,

An unusual class of chiral selectors, cyclofructans, is introduced for the first time as bonded chiral stationary phases. Compared to native cyclofructans (CFs), which have rather limited capabilities as chiral selectors, aliphatic-and aromatic-functionalized CF6s possess unique and very different enantiomeric selectivities. Indeed, they are shown to separate a very broad range of racemic compounds. In particular, aliphatic-derivatized CF6s with a low substitution degree baseline separate all tested chiral primary amines. It appears that partial derivatization on the CF6 molecule disrupts the molecular internal hydrogen bonding, thereby making the core of the molecule more accessible. In contrast, highly aromaticfunctionalized CF6 stationary phases lose most of the enantioselective capabilities toward primary amines, however they gain broad selectivity for most other types of analytes. This class of stationary phases also demonstrates high "loadability" and therefore has great potential for preparative separations. The variations in enantiomeric selectivity often can be correlated with distinct structural features of the selector. The separations occur predominantly in the presence of organic solvents.

A process for easily producing an optically active β-amino alcohol useful as a pharmaceutical intermediate from an inexpensive, readily available starting material is provided. A readily available α-substituted ketone is reacted with an optically active amine to yield a diastereomer mixture of an optically active α-substituted aminoketone. One of the diastereomers is isolated optionally after the diastereomers are converted to salts with an acid. The optically active α-substituted aminoketone or a salt thereof thus isolated was stereoselectively reduced to yield an optically active β-substituted amino alcohol. The optically active β-substituted amino alcohol is subjected to hydrogenolysis to produce an optically active β-amino alcohol or a salt thereof.

An efficient cost-effective process for preparation of l-erythro-2-amino-1-phenyl-1-propanol from l-1-phenyl-1-hydroxy-2-propanone, which comprises converting l-1-phenyl-1-hydroxy-2-propanone to l-1-phenyl-1-hydroxy-2-propanone oxime and reducing the oxime with a catalyst consisting of finely divided nickel and aluminium metals giving good diastereomeric purity and yield.

The invention relates to a method of preparing optically active alcohols which consist substantially (at least 75% e.e.) or entirely of one enantiomer of formula 4 STR1 wherein R and A are as defined therein. The method comprises, which maintaining enantiomeric excess, converting an optically active cyanohydrin of formula 1 STR2 into optically active protected cyanohydrin of formula 2 STR3 converting the protected cyanohydrin of formula 2 into an optically active compound of formula 3 STR4 removing the protecting group B.

The synthesis of both enantiomers of norephedrine and norisoephedrine is described to present a method for the preparation of enantiomerically pure branched 1,2-aminoalcohols.In a one pot reaction enantiomerically pure cyanohydrins bearing an acetal protective group are subjected to Grignard-reaction followed by addition of lithium aluminium hydride.After deprotection the target compounds are obtained.

There is described the resolution of the racemate (1RS,2SR)-2-amino-1-phenyl-propan-1-ol. It is carried out by means of the optical isomers of S-(carboxymethyl)-cysteine.

Several methods are described which allow determination on a small scale of the enantiomer distribution constant Q, and the affinity coefficient P, which characterize the enantioselectivity and the affinity of a lipophilic phase for ammonium salts of different constitution and configuration.The influence of concentration of the tartaric acid ester, temperature, concentration and type of the lipophilic anion on Q and P was investigated to find out favourable experimental conditions for resolutions of racemates by iterative processes, e.g. partition chromatography.The relation ship between Q and the configuration of aminoalcohols 1-12 was explored and the observed regularities are pointed out.In addition it was found that lipophilic tartaric acid esters are enantioselective to salts of threo-1,2-diphenyl-1,2-ethanediamine 13, and to phenylglycine and its derivatives 14-16.

Diastereoisomeric 1-chloro-1-phenyl-2-isothiocyanatopropanes have been prepared.They reacted stereospecifically with CH3ONa, diethylamine, aniline and NaSH to give pure cis or trans-4,5-disubstituted Δ2-thiazolines and thiazolidine-2-thiones whose configuration was determined using the nuclear Overhauser effect.The preponderant conformation of diastereoisomeric 1-chloro-1-phenyl-2-isothiocyanatopropanes was estimated on the basis of coupling constants of vicinal protons.

Optically active bases are prepared by reacting the racemic base with an optically active half amide of an unsaturated aliphatic dicarboxylic acid of the formula STR1 where R1, R2 and R3 are the same of different and are hydrogen, halogen, a hydroxy group, a methyl group or a methoxy group or two of R1, R2 and R3 together are a methylenedioxy group, R4 is hydrogen or a methyl group, R5, R6 and R7 independently are hydrogen or a C1 -C4 alkyl group and n is 0 or 1 and optionally splitting an optically homogeneous salt fraction into the corresponding optically active base and the added half amide.