Enantioselective Synthesis of Chiral 1-Ferrocenyl Alcohol via CBS-Reduction

Reduction of prochiral ferrocenyl ketones 2a-e in the presence of 10 mol% of chiral beta -amino alcohols 4a-b provides 1-ferrocenyl alcohols 1a-e in high yields (> 85%) with high optically purity (e.e. up to 96%).

Enantioselective Synthesis of (+)-Nuciferal, (+)-(E)-Nuciferol and (+)-α-Curcumene by Chiral Hydrogenesterification Reaction

Using chiral hydrogenesterification reaction as the key step, the stereoselective synthesisof (+)-nuciferal 1, (+)-(E)-nuciferol 2 and (+)-α-curcumene 3 has been achieved.

ASYMMETRIC SYNTHESIS Ⅻ:HIGHLY ENANTIOSELECTIVE SYNTHESIS OF α-AMINO ACIDS BY ALKYLATION OF THE KETIMINE FROM 2-HYDROXY-PINAN-3-ONE AND MENTHYL GLYCIN-ATE A DOUBLE ASYMMETRIC INDUCTION SYSTEM

A series of α-amino acids are obtained in 72-96% optical yields by alkylation of the ketimine derived from(+)-2-hydroxy-pinan-3-one and(-)-menthyl glycinate fol- lowed by hydrolysis of the alkylated intermediates with mineral acid.The double asymmetric induction are explained by the transition model of lithium enolate.

Enantioselective Synthesis,(Chir)optical Properties,and Postsynthetic Functionalization of Furan-Containing Oxa[5]-,Oxa[6]-,and Dioxa[6]helicenes

An expedient synthesis of a series of configurationally stable oxa[5]helicenes,oxa[6]helicenes,and dioxa[6]helicenes has been developed using an intramolecular,highly enantioselective,Au-catalyzed,alkyne hydroarylation reaction.The absolute configuration of the newly prepared structures has been established by crystallography,their inversion barriers have been determined theoretically and experimentally,and their chiroptical properties have been investigated.Comparison of these data with those reported for thia-or carbohelicenes sharing an otherwise identical helical framework enables the establishment of comprehensive correlations between the nature of the embedded(hetero)atom(s)and the magnitude of these properties.Preliminary studies on the postsynthetic functionalization of the oxahelicenes obtained are also described.Specifically,siteselective bromination at the 15-position in oxa[5]helicene 5d allows its subsequent manipulation into pyridine-containing aza-oxa[7]helicene 13d;while the two termini of oxa[6]helicene 7d have been intramolecularly cyclised into the pleiadeno[1,12,11-bcde]benzofuran derivative 15d by acidic treatment.Both transformations take place without erosion of the enantiopurity.

Inherently Chiral 6,7-Diphenyldibenzo [e,g][1,4]diazocine: Enantioselective Synthesis and Application as a Ligand Platform

Inherently chiral 6,7-diphenyldibenzo[e,g][1,4]diazocine(DDD)has been synthesized enantioselectively for the first time via chiral phosphoric acid(CPA)-catalyzed cyclocondensation of readily available[1,1′-biphenyl]-2,2′-diamine(1a)and benzil(2a)in 82%yield,with 98%ee under mild reaction conditions.The strategy could also be applied to racemic biaryl diamines through kinetic resolution.The unexpectedly high interconversion energy barriers between the enantiomers(ΔG=39.5 kcal/mol)and the chemical stability rendered DDD an ideal platform for developing new chiral ligands and catalysts.Unique inherently chiralDDD-based phosphoramidites,phosphoric acid,mono-and diphosphine ligands were prepared from optically pure diphenol derivative DDDOL as a common precursor.Preliminary asymmetric reactions catalyzed by Pd or Rh in the presence of newly developed ligands exhibited comparable or even better enantioselectivities than the corresponding BINOLor SPINOL-derived ligands.Density functional theory calculation revealed the origin of the enantioselectivity during the process.

Synthetic studies on pseudolaric acid B:Enantioselective synthesis of C4,C10-di-epi-trans-fused[5-7]-bicyclic skeleton

Studies on the synthesis of antifungal and anticancer natural product,pseudolaric acid B,have led to the enantioselective synthesis of di-epi-trans-fused[5-7]-bicyclic co re skeleton.The synthesis was achieved in 10 linear steps,which features the Sharpless asymmetric epoxidation,cyanide-opening reaction of epoxide,and intramolecular[5+2]cycloaddition reaction as the key transformations.The stereochemistry was determined by the X-ray crystallographic analysis.

Enantioselective Synthesis of Terminal 1,2-Diols from Acyl Chlorides

Optically active terminal 1,2-diols were prepared with high enantiopurity via the TMS-quinidine-catalyzed en- antioselective cyclization of acyl chlorides and oxaziridine, followed by reductive ring-opening of the cycloadducts.

Enantioselective synthesis of indenopyrazolopyrazolones enabled by dual directing groups-assisted and rhodium(Ⅲ)-catalyzed tandem C-H alkenylation/[3+2] stepwise cycloaddition

The Cp;Rh(Ⅲ)-catalyzed asymmetric cascade C-H coupling/intramolecular cyclization of azomethine imines with propargyl carbonates has been developed, affording a variety of chiral tetracyclic indenopyrazolopyrazolone frameworks with good substrate/functional group tolerance and enantioselectivity(up to 97:3 er). Combined experimental studies and DFT calculations revealed the Rh(Ⅲ)-catalyzed stepwise annulation process and clarified the synergy coordination mode of dual directing groups in tuning the selectivity.

First way of enantioselective synthesis of moxifloxacin intermediate

A new method of enantioselective synthesis of （S,S）-2,8-diazobicyclo [4.3.0] nonane was found by using （R）-2-amino-2- phenyl-ethanol as chiral induction reagent. The entire synthetic process included 8 steps which were easy to operate with high yield. The purification method was only simple recrystallization or even used directly in the next step without further purifica- tion. The total yield was 29%.

Enantioselective synthesis of β-amino esters bearing a quinazoline moiety via a Mannich-type reaction catalyzed by a cinchona alkaloid derivative

The cinchona alkaloids catalyzed the direct asymmetric Mannich reactions of 1, 3-dicarbonyl compounds with acyl imines to produce novel β-amino ester derivatives containing a quinazoline moiety. The adducts were isolated with high enantiomeric excess （up to 99%）.

1,6-Asymmetric induction: a higher enantioselective synthesis of γ-butyrolactone

A novel 1,6-asymmetric induction has been observed in the iodolactonization of γ,δ-unsa- turated amides. The optically active γ-butyrolactone was synthesized by employing iodolactonization reaction as a key step.

The enantioselective synthesis of(4S,5S)-and(4S,5R)-5-hydroxy-4-decanolide,the autoregulators from Strepotomyces griseus

(4S,5S)-and(4S,5R)-5-Hydroxy-4-decanolide(1a and 1b),the proposed autoregula- tors from Strepotomyces Griseus were synthesized from a propargyl alcohol 2 in an overall yield of 30%,employing the Sharpless asymmetric epoxidation as the key step.

ENANTIOSELECTIVE TOTAL SYNTHESIS OF 6R-(-)-MASSOIALACTONE

4'R, Z, 2-(4'-hydroxy-2'-nonenyl)-1,3-dioxane 2 which is an intermediate in the synthesis of chiral δ-lactones, has been syntheslzed from dlepoxide 3. Enantioselective total synthesis of 6R-(-)-massoialactone 1 has been achieved from 2 through 4 steps

A Practical Synthesis of (S)-(+)-2-(6-methoxyl-2-naphthyl) propionic Acid

A simplified procedure for enantioselective synthesis of (S)-(+)-2-(6-methoxyl-2- naphthyl) propionic acid ((S)-(+)-naproxen), starting from (6-methoxy-a-naphthyl) -1-propanone, with D-mannitol as auxiliary catalyzed by SmCl3 in onepot is described. The yield is 87.5 %(ee value 99 %).

Synthesis and Crystal Structure of (1S)-1,1'-Bis{[N-ethyl-N-(1-methylethyl)-amino]-carbonyl}-2-(hydroxydiphenylmethyl)-ferrocene

The title complex,(1S)-1,1'-bis{[N-ethyl-N-(1-methylethyl)-amino]carbonyl}-2-(hydroxyldiphenylmethyl)-ferrocene([Fe(C_(24)H_(22)NO_(2))(C_(11)H_(16)NO)]_(2)·H_(2)O,Mr=1207.13),was synthesized via(-)-Sparteine-mediated enantioselective directed ortho-lithiation of 1,1‘-bis{[N-ethyl-N-(1-methylethyl)-amino]carbonyl}-2-(hydroxydiphenylmethyl)-ferrocene.The structure of the rifle compound was determined by X-ray single-crystal diffraction.The crystal belongs to the orthorhombic system,space group P2_(1)2_(1)2_(1),with a=10.266(2),b=17.676(4),c=34.097(7)A,V=6187(2)A3,Z=4,C_(70)H_(86)Fe_(2)N_(4)O_(7),Dc=1.296 g/cm^(3),μ=0.527 mm^(-1),T=113(2)K,F(000)=2568,the final R=0.0469 and wR=0.0984 for 13940 observed reflections with I〉2σ(I).The neighboring ferrocene derivatives are joined into dimers via O-H…O=C intermolecular hydrogen bonding by a water molecule.Besides,the dimers form neat rows along the a axis.

Synthetic Study towards Taurospongin A: Wittig Olefination Approach to the Core Structure

An efficient, convergent and enantioselective synthetic approach to the trihydroxy core structure 2 of Taurospongin A 1 is described. The featured step is a classic Wittig coupling reaction between C1-C4 aldehyde segment 4 and C5-C10 phosphate salt segment (5).

One Stone Two Birds-Enantioselective Bimetallic Catalysis forα-Amino Acid Derivatives with an Allene Unit

Main observation and conclusion A highly enantioselective 2,3-allenylation of acyclic and cyclicα-imino carboxylates via a synergistic bimetallic Pd/Cu catalysis with the same commercially available(R,Rp)-iPr-FOXAP(also as Phosferrox,(R,R)-[2-(4’-i-propyloxazolin-2’-yl)ferrocenyl]diphenyl phosphine)ligand for both metals affording optically active 2,3-butadienylα-amino acid derivatives in high to excellent yields with excellent enantioselectivities has been developed.

A Chiron-based Approach for the Synthesis of Tricyclic Tyrosine Analogue

A chiron approach-based enantioselective synthesis of designed tricyclic tyrosine analogue D-2 was developed. A SmI2-mediated free radical cyclization, an intramolecular Friedel-Crafts reaction and an intramolecular Mannich reaction served as key steps. These key steps were optimized and repeated in good yields. All the stereochemistries in the synthesis were established and confirmed.

Unified total synthesis of eburnamine-vincamine indole alkaloids based on catalytic asymmetric hydrogenation/lactamization cascade

The enantioselective total synthesis of representative members of the eburnamine-vincamine alkaloids(+)-vincamine,(-)-eburnamonine,and(-)-criocerine has been accomplished.The synthesis took advantage of a highly stereoselective Ir-catalyzed hydrogenation/lactamization cascade reaction,which allows for the stereo-selective construction of the C/D rings as well as the installation of the critical cis-C20/C21 relative stereo-chemistry of the eburnamine-vincamine alkaloid skeleton in one pot.

Chiral Oxazaborolidine-catalyzed Asymmetric Borane Reduction of Alkyl 4-Dialkylaminophenyl Ketones

A series of alkyl 4-dialkylaminophenyl ketones were prepared and reduced asymmetrically by borane under the chiral oxazaborolidine catalysis. The results indicate that the ketones show a more obvious subsfituent effect on the enanfioselectivity than the corresponding 4-alkyl/alkoxy/alkylthiophenyl ketones in the asymmetric reduction because of the existence of a strong coordinate nitrogen atom with the boron atom in the catalyst and borane.