摘要:
2.2. 1,3-imidazolidine-4-ones having the General Formula: ##STR1## are obtained in a pure form especially by means of precipitation, in which production an optically active acid can be used at 0.5-0.8 eq. for the separation of racemates. The non-desired enantiomer can be racemized in an inert solvent and the cyclization to imidazolidinone can take place by means of the optically active acid, whereupon the separation of racemates takes place directly thereafter. 1,3-imidazolidine-4-ones are valuable educts for the preparation of branched or unbranched, proteinogenic or non-proteinogenic .alpha.-amino acids by means of diastereoselective alkylation and subsequent ring splitting.
摘要:
A process employs amidine or amidine base and a metal compound in the presence of an alcohol or water to transesterify, or saponify esters or amides. Since the process employs relatively mild conditions, it is especially suitable for the production of optically active substances and biomolecules, e.g. peptides, amino acids and nucleic acids which are sensitive to elevated temperatures, extreme pH values and/or long reaction times since these compounds are easily racemised or denatured. The conditions additionally find use in solid phase systems. When amino acid or peptide esters are saponified, the splitting is brought about with lithium hydroxide alone under mild conditions. The use of an amidine base, more particularly DBU or DBN, in combination with the metal salt additionally accelerates the reaction so strongly that even sensitive acid derivatives can be reacted under mild conditions. The amidine based system lends itself to the manufacture of complex esters, gentle splitting of peptides from the carrier, gentle saponification of amides or esters.
摘要:
It has been found that nonimmunosuppressive, cyclophilin-binding cyclosporins are useful in the treatment and prevention of AIDS and AIDS-related disorders. Such cyclosporins include novel Ciclosporin derivatives modified at the 4- and/or 5-positions.
摘要:
An aldehyde (R.sup.1 CHO) and optically active 3-hydroxybutyric acid (CH.sub.3 CH(OH)CH.sub.2 COOH) are reacted to form an optically active dioxanone. This dioxanone is reacted with a compound R.sup.2 --X to form an intermediate (R.sup.1 R.sup.2 CHOCH(CH.sub.3) CH.sub.2 COOH) which is then subjected to elimination to form an optically active secondary alcohol (R.sup.1 R.sup.2 CHOH) in good yield and purity.
摘要:
The present invention relates to chemical compounds and in particular to substituted dioxanones obtained from (R)-3-hydroxybutyric acid. This invention also relates to a method for the production of such dioxanones and to processes using such dioxanones as starting-materials.
摘要:
TADDOL dendrimers are described. Their use as crosslinkers in polymerisation reactions and the use of Ti salts of polymer-bound TADDOL dendrimers as catalysts in enantioselective addition reactions is disclosed.
摘要:
Cyclosporins e.g. of formula II ##STR1## in which X is -MeBmt- or -dihydro-MeBmt- andY is -.alpha.Abu-, -Thr-, -Val- or -Nva-,wherein the residue at the 3-position, i.e. the residue Z in formula II, is an optically active, .alpha.-N-methylated .alpha.-amino acid residue of the (D)-configuration, possess pharmaceutical, in particular immunosuppressive, anti-inflammatory and anti-parasitic activity. Intermediate cyclosporin poly-anions having a de-protonated sarcosyl residue at the 3-position, e.g. polyanions of cyclosporins of formula II above wherein X and Y have the meanings given above and Z is -Sar-, in which the said residue Z is de-protonated, are also novel and part of the invention.
摘要:
An aldehyde (R.sup.1 CHO) and optically active 3-hydroxybutyric acid (CH.sub.3 CH(OH)CH.sub.2 COOH) are reacted to form an optically active dioxanone. This dioxanone is reacted with a compound R.sup.2 --X to form an intermediate (R.sup.1 R.sup.2 CHOCH(CH.sub.3) CH.sub.2 COOH) which is then subjected to elimination to form an optically active secondary alcohol (R.sup.1 R.sup.2 CHOH) in good yield and purity.
摘要翻译:使醛(R 1 CHO)和光学活性的3-羟基丁酸(CH 3 CH(OH)CH 2 COOH)反应以形成光学活性的二恶烷酮。 该二恶烷酮与化合物R2-X反应形成中间体(R 1 R 2 CHOCH(CH 3)CH 2 COOH),然后以良好的产率和纯度形成光学活性仲醇(R 1 R 2 CHOH)。
摘要:
Fluorinated nitroalcohols of the formula (I) ##STR1## process for their preparation by reaction of fluoronitroalkane of the formula (II) ##STR2## with a carbonyl compound of the formula (III) ##STR3## fluorinated aminoalcohols of the formula (IV) ##STR4## and a process for their preparation by hydrogentation of compounds of the formula (I).
摘要:
The manufacture of optically active compounds of the formula ##STR1## wherein R.sup.1 signifies alkyl, phenyl or benzyl and R.sup.2 signifies hydrogen or a customary ester residue,by the fermentative reduction of compounds of the formula ##STR2## wherein R.sup.1 and R.sup.2 have the above significance. The compounds obtained are valuable intermediates in organic syntheses.