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:
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:
A process for the purification of 1,4-butanediol mononitrate from 1,4-butanediol dinitrate and 1,4-butanediol, by selective extraction with solvents is herein disclosed.
摘要:
A process for obtaining nitroxyalklesters of the 2(S)(6-methoxy-2-naphthyl)-propanoic acid having an enantiomeric excess higher than or equal to 95%, preferably higher than or equal to 98%, characterized in that an halide of the 2-(S)-(6 methoxy-2-naphthyl)propanoic acid of formula A-Hal, wherein A is the acid acyl residue, is reacted in an inert organic solvent with an aliphatic nitroxyalkanol HO—Y—ONO2, wherein Y is a C2-C20 alkylene or a cycloalkylene from 3 to 8 carbon atoms, or an alkylene as defined containing a cycloalkylene as defined, in the presence of an inorganic base.