Use of shift reagent with MTPA derivatives in19F NMR spectrocopy: IV—Determination of enantiomeric composition for a variety of secondary cycloalkanols. A survey
摘要:
AbstractChiral secondary cycloalkanols (monocyclic alcohols) are derivatized to the corresponding (R)‐α‐methoxy‐α‐trifluoromethyl‐α‐phenylacetic acid [(R)‐MTPA] esters and analysed by 19F NMR in the presence of tris(6,6,7,7,8,8,8‐heptafluoro‐2,2‐dimethyl‐3,5‐octanedionato) europium(III) [Eu(fod)3]. Using this method the enantiomeric composition can be measured for several cyclopentanols, cyclohexanols and cycloheptanols, with a variety of substitution patterns. It is shown that a mixture of four stereoisomeric cycloalkanols, such as cis and trans disubstituted alcohols, can be analysed simultaneously.
ORGANIC SALTS AND METHOD FOR PRODUCING CHIRAL ORGANIC COMPOUNDS
申请人:List Benjamin
公开号:US20090030216A1
公开(公告)日:2009-01-29
The invention relates to a method for producing chiral organic compounds by asymmetric catalysis, using ionic catalysts comprising a chiral catalyst anion. The claimed method is suitable for reactions which are carried out over cationic intermediate stages, such as iminium ions or acyl pyridinium ions. The invention enables the production of chiral compounds with high ee values, that until now could only be obtained by means of costly purification methods.
Enantioselectivecopper-catalyzed 1,4-addition of dialkylzincs to enones proceeded in the presence of 0.1 mol % of Cu(OTf)2 and 0.25 mol % of an N,N,P-ligand containing a quinoline moiety to afford...
Hydroxy-amide Functionalized Azolium Salts for Cu-Catalyzed Asymmetric Conjugate Addition: Stereocontrol Based on Ligand Structure and Copper Precatalyst
designed and synthesized for Cu-catalyzed asymmetric conjugate addition reaction. The (CH2)2-bridged hydroxy-amide functionalized azolium ligand precursors 2, in addition to the previously reported CH2-bridged azolium salts 1, have been prepared from readily available enantiopure β-amino alcohols. The combination of a Cu species with 1 or 2 efficiently promoted the 1,4-addition reaction of cyclic enones
Cyclic ketones, their preparation and their use in the synthesis of amino acids
申请人:——
公开号:US20030187296A1
公开(公告)日:2003-10-02
A method is provided for making an enantiomerically pure of the formula: in which R and R′ represent C1?C10 alkyl, C2?C10 alkenyl or C3?C10 cycloalkyl and the wedges signify (S)- or (R)-stereochemistry, the substituents in compound (II) being trans. Conjugate addition is carried out between an organometallic nucleophile that provides a group R as defined above and (R)-4-acetoxycyclopent-2-en-1-one, (S)-4-acetoxycyclopent-2-en-1-one or a similar compound in which acetoxy is replaced by another leaving group to give, e.g. in the case of the acetoxy compound, a trans 3,4-disubstituted addition product of formula III or IV; The acetyl group is eliminated from the addition product to give an (R)- or (S)-4-alkyl or 4-alkenyl cyclopent-2-en-1-one the compound of formula is then to be hydrogenated to give a cyclopentanone of formula (I) or conjugate addition of a second organometallic nucleophile that provides a group R′ as defined above to the compound of the above formula may be carried out to give a trans 3,4-disubstituted addition product of formula (II). One of the above compounds may be converted e.g. via an intermediate (XV)-(XVIII) (in which the substituents R and R′ and the wedges have the meanings indicated above) to a gabapentin analogue of one of the formulae shown below: in which the substituents R and R′ and the wedges also have the meanings indicated above.
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2
asymmetric 1,4-addition of Et2Zn to 2-cyclohexen-1-one using a Cu(I) salt/N-heterocyclic carbene (NHC)–Ag complex catalytic system afforded optically active 3-ethylcyclohexanone. The reversal of enantioselectivity using the same catalytic system was achieved by changing the order of the addition of substrates.