摘要:
A stereoconvergent process is described for preparing optically active alpha-arylalkanoic acids using as starting substance a diastereoisomeric mixture of ketals of formula ##STR1## in which the substituents have the meanings given in the description. The described process leads to the formation of a single enantiomer.
摘要:
Compounds of formula ##STR1## wherein Ar represents an optionally substituted aryl group;R represents a C.sub.1 -C.sub.4 alkyl;R.sub.1 and R.sub.2, equal to or different from each other, represent hydroxy, O.sup.- M.sup.+, OR.sub.3 or ##STR2## group, R.sub.3 represents a C.sub.1 -C.sub.24 alkyl, a C.sub.3 -C.sub.6 cycloalkyl, a phenyl or a benzyl;M.sup.+ represents the cation of an alkaline metal;R.sub.4 and R.sub.5, equal to or different from each other, represent a hydrogen atom, a C.sub.1 -C.sub.4 alkyl, a C.sub.5 -C.sub.6 cycloalkyl, a (CH.sub.2).sub.n --CH.sub.2 OH group with n=1, 2 or 3, or R.sub.4 and R.sub.5 together are a group (CH.sub.2).sub.m with m=4 or 5, a group --CH.sub.2 --CH.sub.2 --R.sub.6 --CH.sub.2 --CH.sub.2 -- in which R.sub.6 is an oxygen atom, an N--H or N--(C.sub.1 -C.sub.4) alkyl group;X represents a chlorine, bromine or iodine atom, an hydroxy, acyloxy, alkylsulphonyloxy or arylsulphonyloxy group;the carbon atoms marked by an asterisk are both contemporaneously in the R or S configuration, are described.The preparation of the compound of formula I by ketalization or by trans-ketalization with tartaric acid derivatives and their rearrangement into alpha-arylalkanoic acids is decribed too.
摘要:
Compounds are described of formula ##STR1## in which: Ar represents a aryl, possibly substituted;R represents a C.sub.1 -C.sub.4 alkyl;R' represents a hydroxyl, an alkoxy, an amino group possibly mono or di-alkyl substituted, or an O-M+ group where M+ represents the cation of an alkaline metal;X represents a hydrogen, chlorine, bromine or iodine atom, a hydroxyl, or an acyloxy, alkylsulphonyloxy or arylsulphonyloxy group.The compounds of formula I can be easily transformed into alphaarylalkanoic acids of formula ##STR2## in which Ar and R have the aforesaid meanings.
摘要:
A process is described for preparing optically active alpha-halogenated carbonyl compounds.This process consists of transforming the carbonyl compound into the corresponding acetal with tartaric acid or a derivative thereof, halogenating this acetal and releasing the carbonyl compound.
摘要:
Process for preparing alkanoic acid or their esters by rearrangement of alpha-halo-ketones in protic medium and in the presence of a non-noble metal salt.The protic medium is preferably an aliphatic alcohol having low molecular weight or water and the reaction is carried out at a temperature from 0.degree. C. to the boiling-point of the diluent or of the diluents mixture.
摘要:
Process for preparing esters of 2-(6'-methoxy-2'-naphtyl)-propionic acid via rearrangement of new ketals of 2-halo-1-(6'-methoxy-2'-naphtyl)-propan-1-one in the presence of a Lewis acid.The esters thus obtained are useful as intermediate products for preparing Naproxen.The process involves the preparation of the following new compounds:ketals of 2-halo-1-(6'-methoxy-2'-naphtyl)-propan-1-oneesters of 2-(5'-bromo-6'-methoxy-2'-naphtyl)-propionic acid1-(5'-bromo-6'-methoxy-2'-naphtyl)-propan-1-one2-halo-(5'-bromo-6'-methoxy-2'-naphtyl)-propan-1-one
摘要:
A process is disclosed for the preparation of optically active alpha-arylalkanoic acids, consisting in the rearrangement of optically active alpha-(haloalkyl)-aryl-ketals and in submitting to hydrolysis the so-obtained esters of alpha-arylalkanoic acids.The rearrangement reaction is carried out under neutral or slightly alkaline conditions in a polar protic medium.
摘要:
Process for preparing esters of 2-(6'-methoxy-2'-naphthyl)-propionic acids via rearrangement of ketals of 2-iodo-1-(6'-methoxy-2'-naphthyl)-propan-1-one in a protic medium.
摘要:
Alpha substituted alkylarylketals of formula: ##STR1## wherein Ar is an aromatic radical having from 3 to 20 C atoms,X is halogen, OR.sub.3 (wherein R.sub.3 is H, acyl or aroyl), OSO.sub.2 CH.sub.3 or OSO.sub.2 C.sub.6 H.sub.4 --CH.sub.3,R is H or alkyl having from 1 to 3 C atoms,Y is --CH.sub.2 --C(R.sub.1).dbd.C(R.sub.2)--CH.sub.2 --(wherein, in turn, R.sub.1 and R.sub.2 are H or methyl).The products of formula I are useful for preparing alpha-aryl-alkanoic acids.
摘要:
This invention relates to a process for the preparation of 4-[2-(dimethylamino)-ethoxy]-2-methyl-5-(1-methylethyl)-phenol esters (I) and their salts with organic and inorganic acids comprising the reaction of thymol with a salt of an 1-halo-dimethylaminoethane to obtain ethylamine-N,N-dimethyl-2-(thymyloxy) (II), the subsequent reaction of (II) with an acylating agent according to the Friedel and Kraft reaction to obtain 4-[2-(dimethylamino)-ethoxy]-2-methyl-5-(1-methylethyl)-1-acyl-benzene (III) and the oxidation of (III) to obtain the products (I) which, if desired, may be transformed in their salts with organic or inorganic acids.This process allows to obtain the products (I) in high quality and quantity without isolating any intermediate product.