- Chiral azo-heterocyclic carbene precursor compound with bicyclic framework and preparation method thereof
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The invention discloses a chiral azo-heterocyclic carbene precursor compound with a bicyclic framework and a preparation method thereof. A series of the chiral azo-heterocyclic carbene precursor compound with the bicyclic framework is obtained by taking c
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Paragraph 0082; 0083; 0084; 0085; 0090; 0092; 0093
(2019/01/22)
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- Modular synthesis of new bicyclic carbene precursors
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A series of new N-heterocyclic carbene (NHC) precursors, containing bicyclic pyrrolo[1,2-c]imidazole framework, were prepared from N-(tert-butoxycarbonyl)-L-proline (1-Boc-L-proline). The sequential attachment of nitrogen nucleophiles and subsequent ring
- Li, Jie,Yao, Jiaqi,He, Weiping,Yang, Fan,Liu, Xiaoming
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p. 951 - 954
(2019/11/22)
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- Transfer hydrogenation reactions catalyzed by chiral half-sandwich Ruthenium complexes derived from Proline
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Chiral ruthenium half-sandwich complexes were prepared using a chelating diamine made from proline with a phenyl, ethyl, or benzyl group, instead of hydrogen on one of the coordinating arms. Three of these complexes were obtained as single diastereoisomers and their configuration identified by X-ray crystallography. The complexes are recyclable catalysts for the reduction of ketones to chiral alcohols in water. A ruthenium hydride species is identified as the active species by NMR spectroscopy and isotopic labelling experiments. Maximum enantio-selectivity was attained when a phenyl group was directly attached to the primary amine on the diamine ligand derived from proline. [Figure not available: see fulltext.]
- Pandia Kumar, Arun Kumar,Samuelson, Ashoka G
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p. 1405 - 1415
(2016/09/19)
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- Synthesis and characterization of new chiral azolinium salts, precursors to N-heterocyclic carbenes, derived from l-proline
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A short and flexible procedure for the preparation of seven chiral azolinium and five functionalized chiral azolinium salts, precursors to N-heterocyclic carbenes, derived from l-proline has been developed. Moderate to good overall yields were obtained. Some NHC dimers and thiones were isolated. X-ray crystal structure determinations of two [Rh-NHC] complexes were also reported.
- Thomasset, Amélia,Bouchardy, Lucie,Bournaud, Chloée,Guillot, Régis,Toffano, Martial,Vo-Thanh, Giang
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p. 242 - 250
(2014/03/21)
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- Chiral amine catalyzed enantio- and diastereoselective Michael reaction in brine
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Simple pyrrolidine-based chiral amines were synthesized and used for the Michael addition of different ketones to a variety of nitro-olefins in brine. The effect of different surfactants and acids on the yields and stereochemical outcome of the Michael ad
- Singh, Sarbjit,Chimni, Swapandeep Singh
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p. 1068 - 1079
(2012/11/06)
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- Enantiomerically pure cyclopalladated diazaphospholidine
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Enantiomerically pure (S)-2-(anilinomethyl)pyrrolidine (S)-2 was obtained from (S)-proline using a modified four-step procedure in a total yield of 56%. Diamine (S)-2 was converted to diazaphospholidine (S)-1 using oTolP(NMe2)2
- Dunina, Valery V.,Gorunova, Olga N.,Stepanova, Valeriya A.,Zykov, Pavel A.,Livantsov, Michail V.,Grishin, Yuri K.,Churakov, Andrey V.,Kuz'mina, Lyudmila G.
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p. 2011 - 2015
(2008/02/11)
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- Synthesis and characterization of chiral 1,2-diamines from 5-oxo-pyrrolidine-(S)-2-carboxylic acid
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Unsymmetrical chiral secondary vicinal diamines were synthesized by applying a modified three-step reaction. The key step in this sequence is a primary amine mediated ring opening reaction of a diastereomeric oxazolidinone derivative. A possible mechanism
- Koehn, Uwe,Schramm, Andrea,Kloss, Florian,Goerls, Helmar,Arnold, Evelyn,Anders, Ernst
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p. 1735 - 1741
(2008/02/11)
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- Method for preparing 2-(2-arylmorpholin-2-yl)ethanol derivatives and intermediates
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The invention relates to a process for the preparation of substituted 2-(2-arylmorpholin-2-yl)ethanol derivatives.
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Page/Page column 39
(2010/11/08)
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- Conformational arm-wrestling: Battles for stereochemical control in benzamides bearing matched and mismatched chiral 2- and 6-substituents
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The orientation of a tertiary amide group adjacent to an aromatic ring may be governed by the stereochemistry of an adjacent chiral substituent. With a chiral substituent in both ortho positions, matched/mismatched pairs of isomers result. Evidence for ma
- Clayden, Jonathan,Foricher, Yann J. Y.,Helliwell, Madeleine,Johnson, Paul,Mitjans, David,Vinader, Victoria
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p. 444 - 454
(2008/01/27)
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- Synthesis and application to asymmetric allylic amination of substituted monodonor diazaphospholidine ligands
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The synthesis of a series of substituted monodonor diazaphospholidine ligands is described. A regioselective lithiation process is a key step in one of these syntheses. The compounds are designed to be incorporated into soluble polymer and other solid pha
- Edwards, Christopher W.,Shipton, Mark R.,Alcock, Nathaniel W.,Clase, Howard,Wills, Martin
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p. 6473 - 6480
(2007/10/03)
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- Enantioselective rhodium catalyzed hydroboration of olefins using chiral bis(aminophosphine) ligands
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The synthesis of new chiral bis(aminophosphine) ligands 1-5 was achieved and assessed in the enantioselective rhodium catalyzed hydroboration of various olefins with catecholborane. Enantioselectivities up to 77% were obtained.
- Brunel, Jean-Michel,Buono, Gerard
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p. 3561 - 3564
(2007/10/03)
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- Chiral reductions of imines leading to the syntheses of optically active amines
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A process for preparing an R enantiomer of a compound of the formula (I): STR1 wherein Ar is 3-methoxyphenyl, 3-chlorophenyl, or 1-naphthyl, and X is independently selected from the group consisting of H, F, Cl, Br, I, phenyl, CF3, CF2 H, CFH2, lower alkyl (e.g., Me), O-lower alkyl (e.g., OMe), OCH2 CF3, OH, CN, NO2, C(O)-lower alkyl (e.g., C(O)Me), C(O)O-lower alkyl (e.g., C(O)OMe), C(O)NH-lower alkyl (e.g., C(O)NH--Me), C(O)N-lower alkyl2 (e.g., C(O)NMe2), OC(O)-lower alkyl (e.g., OC(O)Me), and NH--C(O)-lower alkyl (e.g., NH--C(O)Me), where "lower alkyl" is selected from a group consisting of 1 to 6 carbon atoms, and m is an integer between 1 and 5, by asymmetrically and enantioselectively reducing an imine with a reducing agent/chiral auxiliary agent complex so as to produce an enantiomeric excess of R enantiomer of the compound of formula (I) over the S enantiomer of the compound of formula (I). The process is especially useful to produce compounds (R)-(+)-N-[1-(3-methoxyphenyl)ethyl]-3-(2-chlorophenyl)propanamine and (R)-(+)-N-[1-(3-methoxyphenyl)ethyl]-3-(phenyl)propanamine. Enantiomeric excess of the R enantiomer over S enantiomer of greater than 65% have been achieved.
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- Stereocontrolled route to some optically active β-hydroxy phosphine oxides using the stereoselective addition of metallated phosphine oxides to proline-derived keto aminals
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An asymmetric Horner-Wittig addition reaction with a chiral auxiliary attached to the electrophile is described. The key step is the addition of metallated phosphine oxides to Mukaiyama's proline-derived keto aminals (for which improved syntheses are described) and a detailed study of the factors affecting the stereoselectivity of these reactions is presented. In particular, by suitable choice of metallation conditions, complementary stereoselectivities are observed: reactions in THF with no additives are syn selective (Felkin non-chelation control) whereas reactions in toluene with added lithium bromide are anti selective (Cram chelation control).
- O'Brien, Peter,Warren, Stuart
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p. 2117 - 2127
(2007/10/03)
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- THE PREPARATION OF OPTICALLY ACTIVE PHOSPHINES BY ASYMMETRIC REDUCTION OF RACEMIC PHOSPHINE OXIDES
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The reduction of (R,S)-1-phenyl-3-methyl-2-phospholene 1-oxide (3) with lithium aluminium hydride has been studied to explain some of the anomalies reported for the reduction of (3) with optically active alanes.Reductions of acyclic racemic chiral phosphines oxides using optically active alanes and lithium aluminium hydride doped with (S)-2-(anilinomethyl)-pyrrolidine is reported, both giving optically active phosphines with low enantiomeric excesses.
- MacPherson, Andrew J.,Smith, David J. H.
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p. 315 - 345
(2007/10/02)
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- Dedoublement et determination de la configuration absolue des enantiomeres de l'acide (thienyl-3)-2 cyclohexyl-2 hydroxy-2 acetique. Application a la synthese d'esters anticholinergiques du quinuclidinol-3
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Enantiomeric 2-(3-thienyl)-2-cyclohexyl-2-hydroxy acetic acids 1 were obtained by the resolution of (+/-)-1 using (+)- and (-)-ephedrine as the resolving agents, and by asymmetric synthesis; (+)-1 was assigned S absolute configuration (i) by comparing the circular dichroism spectra of a series of derivatives of 1 with those of the corresponding derivatives of S-(+)-2-phenyl-2-cyclohexyl-2-hydroxy acetic acid 1', and (ii) by application of the quasi-racemate method.On transesterification of the methyl esters of 1, R-(+)-2 and S-(-)-2, with R-(-)- or S-(+)-1-azabicyclo-3-octanol (or 3-quinuclidinol), the four diastereoisomers of 3-quinuclidinyl 2-(3-thienyl)-2-cyclohexyl-2-hydroxy-acetate were obtained, i.e., (+)-2R, 3'S-6, (-)-2S, 3'R-6, (+)-2R, 3'R-7, and (-)-2S, 3'S-7.These compounds exhibited anticholinergic activity.
- Tambute, Andre,Collet, Andre
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- ASYMMETRIC SYNTHESIS OF A CHROMAN DERIVATIVE (VITAMIN E PRECURSOR)
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Chromanmethanol 2, a chiral intermediate for the synthesis of α-tocopherol 1, is prepared from α-hydroxy aldehyde 5, which is obtained by an asymmetric synthesis in over 95percent ee.
- Sakito, Yoji,Suzukamo, Gohfu
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p. 4953 - 4954
(2007/10/02)
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- ASYMMETRIC SYNTHESIS BASED ON CHIRAL DIAMINES HAVING PYRROLIDINE RING
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Various highly stereoselective asymmetric reactions based on chiral diamines having pyrrolidine ring are described.Some of these reactions have been successfully applied to the syntheses of natural products.
- Mukaiyama, Teruaki
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p. 4111 - 4119
(2007/10/02)
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- AN ASYMMETRIC SYNTHESIS OF β-FORMYL β-HYDROXY ESTERS
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Optically active β-formyl β-hydroxy esters are prepared in high enantiomeric excess by treating 2-acyl-1,3-diazabicyclo-octane derivatives, prepared from (S)-2-(substituted aminomethyl)-pyrrolidine and phenylglyoxal monohydrate or methyl hydroxymethoxyacetate, with metal enolates of ethyl acetate.
- Sakito, Yoji,Asami, Masatoshi,Mukaiyama, Teruaki
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p. 455 - 458
(2007/10/02)
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