Synthesis and Absolute Configuration of (2S,3S,3aS,6S,7aR)-2,3-Dihydroxy-2-((R)-1-hydroxy-3-methylbutyl)-3,6-dimethylhexahydrobenzofuran-4(2H)-one

To investigate the anti-ulcer effect of bisabolangelone reduction derivatives, the sesquiterpene was further proceeded with dihydroxylation reaction. The structure of the target compound was characterized by IR, ESI-MS, 2D NMR and elemental analysis, and its absolute configuration was confirmed with a Flack parameter of 0.08(16) by X-ray crystallography using a Cu radiation source. Compound(3), C_(15)H_(26)O_5, crystal data: monoclinic system, space group P2_1, a = 11.467(2), b = 6.0303(12), c = 11.711(2) ?, β = 99.70(3)°, V = 798.3(3) ?~3, Z = 2, F(000) = 312, D_c = 1.191 g/cm~3, μ = 0.723 mm~(-1), R = 0.0303 and wR = 0.0797 for 2590 independent reflections(Rint = 0.0164) and 2563 observed ones(I 2σ(I)).     

Synthesis and Absolute Configuration of((2R,3R,6S)-3-Hydroxy-6-(naphthalen-2-ylthio)-3,6-dihydro-2H-pyran-2-yl)methyl Pivalate

A stereo-selective palladium-catalyzed one-pot Tsuji-Trost reaction was used to prepare four β-thiogalactosides from unsaturated D-galactal and thiol. Their structures were characterized by nuclear magnetic resonance spectra and high-resolution electrospray ionization mass spectra. The absolute configuration was confirmed with a Flack parameter of 0.019(15) by X-ray crystallography using a Cu radiation source. Compound 6 a(C_(21) H_(24) O_4 S): orthorhombic system, space group P2_12_12_1, a = 9.0919(4), b = 9.6313(4), c = 22.5936(11) ?, V =1978.45(15) ?~3, Z = 4, F(000) = 792, Dc = 1.250 g/cm~3, μ = 1.636 mm~(-1), R = 0.0478 and w R = 0.1384 for 3621 independent reflections(Rint = 0.0390) and 3326 observed ones(I 2σ(I)). 3-(4,5)-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide(MTT) cell viability assays indicated that these thiogalactosides showed anti-proliferative activities against human gastric cancer HGC-27 cells with IC50 values of 69～88 μM.     

Absolute Conformation and Configuration of (2S, 3S)-3-Acetoxy-5-(dimethylaminoethyl)-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one Chloride (Dilthiazem Hydrochloride)

Resolution of racemic cis-3-(2-aminophenylthio)-2-hydroxy-3-(4-methoxyphenyl) propionic acid ( 2 ) via the cinchonidine salt 3 , and brucine salt 4 , isolation of the calcium salts (+)- and (?)- 5 , as well as their cyclization to enantiomeric 1,5-benzothiazepines (+)- and (?)- 1 , are described. X-Ray single-crystal analysis reveals (2S, 3S) absolute configuration of (+)- 1 on the basis of tentative comparison of CD data with those for the 1,4-benzodiazepine derivative (+)- 8 of known absolute configuration.     

Crystal Structure and Absolute Configuration of (+)-(1S, 2R)-5, 6-Dimethylidene-2exo-norbornyl-exo-irontricarbonyl p-Bromobenzoate

The title complex (+)- 13x has been prepared in an enantiomerically pure form. Its absolute configuration has been determined by single-crystal X-ray diffraction and has been correlated chemically to that of the 5, 6-dimethylidene-2-norbornyl derivatives (—)- 1 , (—)- 2 , (—)- 3 and to (—)-(1S, 2R)-benzonorborn-5-en-2-yl acetate (s. Scheme 1), whose configuration was deduced by indirect techniques. A critical analysis of the chiroptical properties of the exocyclic dienes 1–3 is now possible. These compounds are limiting systems for the application of the allylic axial chirality rule, the generalized octant rule and the symmetry rule for βγ-unsaturated ketones.     

Crystal and molecular structure of methyl(±)-2-((1R,3R)-3-{ 2-[(3S)-1-ethyl-3-hydroxy-2-oxo-2,3-dihydro-1H-3-indolyl]acetyl}-2,2-dimethylcyclobutyl) acetate

The structure of methyl (±)-2-((1R,3R)-3-{ 2-[(3S)-1-ethyl-3-hydroxy-2-oxo-2,3-dihydro-1H-3-indolyl]acetyl}-2,2-dimethylcyclobutyl) acetate has been determined by single crystal X-ray diffraction. The crystal belongs to triclinic system; parameters of the unit cell are: a = 6.551(1) Å, b = 11.506(1) Å, c = 14.334(1) Å, α = 101.41(1)°, β = 97.57(1)°, γ = 104.72(1)°; space group P-1, Z = 2, composition C₂₁H₂₇NO₅. The structure of N-ethyloxindole fragment is usual for the present class of compounds. The configuration of the formed asymmetric carbon atom C(3) of the pyrrole ring along with the configuration of C(12) and C(14) atoms of 2,2-dimethylcyclobutane ring form the side chain of the molecule were determined. There is observed the generation of centrosymmetrical dimers in the crystal structure due to realized intermolecular hydrogen bond of O-H...O type, 2.808(2) Å.     

Synthesis and Crystal Structure of 7-((7S)-7-Aminospiro[2.4]heptan-5-yl)-8-chloro-6-fluoro-1-((1R,2S)-cis-2-fluorocyclopropyl)-4-oxo-1,4-dihydroqun-oline-3-carboxylic Acid Fumaric Acid Monohydra

A new compound [C_(19)H_(19)N_3O_3F_2Cl·C_4H_3O_4·H_2O](I),(7-((7S)-7-aminospiro[2.4]heptan-5-yl)-8-chloro-6-fluoro-1-((1R,2S)-2-fluorocyclopropyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid fumaric acid monohydrate), was synthesized and structurally characterized by single-crystal X-ray diffraction, 1H NMR, 14 C spectra and mass spectra. I crystallizes in monoclinic, space group P21/c with a = 8.495(2), b = 12.545(3), c = 11.832(3) ?, β = 103.37(1)°, V = 1226.8(5) ?3, Z = 2, Mr = 543.90, Dc = 1.472 g/cm3, F(000) = 564, μ = 0.225 mm-1, the final R = 0.0307 and w R = 0.0892 for 6886 observed reflections with I 2σ(I). X-ray diffraction analysis reveals that the quinolinone ring is almost coplanar, and the pyrrole ring adopts an envelope form. Packing of crystal I is constructed and stabilized by the N–H···O, O–H···O and N–H···Cl hydrogen bonds together with C–H···π interations.     

Asymmetric Synthesis of (3R, 5R)-3-((tert-Butyldimethylsily)oxy)-5-((Z)-2-Bromovinyl)-Tetrahydro-Furan-2-one, an Intermediate for the Synthesis of Fostriecin

Fostriecin(CI-920) 11 a potential anticancer agent presently in phase I clinical trials at NCI is a novel phosphate ester produced by Streptomyces pulveraceus. Scheme 1 1 2 3 5 4 Synthesis of C10 epimer of compound 1 had been reported by Just G2. during the determination of its structure. On the basis of Just’s synthesis, a revised retro-asymmetric synthetic route of Fostriecin (scheme 1) was designed here of which compound 3 was synthesized from 5 with C3 in R configuration correspondi…     

Heterotricyclodecane XX (+)-(1S, 3S, 6S, 8S)- und (−)-(1R, 3R, 6R, 8R)-2, 7-Dioxa-twista-4,9-dien

(+)-(1S, 3S, 6S, 8S)- and (?)-(1R, 3R, 6R, 8R)-2,7-dioxa-twista-4,9-diene. A synthesis and the determination of the sense of chirality of (+)-(1S, 3S, 6S, 8S)- and (?)-(1R, 3R, 6R, 8R)-2,7-dioxa-twista-4,9-diene ((+)- 5 and (?)- 5 , respectively) is described.     

Synthesis,Crystal Structure and Biological Activity of(2,4-Dihydroxy-3,6-dimethoxyphenyl)-((1R,2S,3S,4R,7R)-7-isopropyl-5-methyl-3-phenylbicyclo[2.2.2]-oct-5-en-2-yl)methanone

The crystal structure of the natural terpene derivative(2,4-dihydroxy-3,6-dimethoxyphenyl)((1 R,2 S,3 S,4 R,7 R)-7-isopropyl-5-methyl-3-phenylbicyclo[2.2.2]oct-5-en-2-yl)-methanone was determined by single-crystal X-ray diffraction method. The compound crystallizes in triclinic,space group P21/c with a = 16.1444(9), b = 16.5294(9), c = 19.7875(11) ?, V = 5280.4(5) ?3, Z = 4,Dc = 1.209 g/cm~3, F(000) = 2064, μ(Cu Kα) = 0.675 mm-1, S = 1.069, R = 0.0520 and wR(I 2σ(I))= 0.1392. The spiro structure constructed by Diels-Alder reaction was highly symmetric. In addition,the title compound showed inhibitory activities against cancer cell line with varied potencies.     

Preparation of Enantiomerically Enriched (2R,3R)- or (2S,3S)-trans-2,3-Diaryloxiranes via Camphor-Derived Sulfonium Ylides

Easily available D-(+)-camphor-derived sulfides 3, 4, 6, and 7 were employed for enantioselective epoxidation via an ylide route. When benzylated or methylated sulfides were used as reagents or mediators for benzylidene transfer, stoichiometric and catalytic epoxidations were realized, respectively. Opposite asymmetric induction was achieved only when sulfides containing exo- (3 and 4) and endo- (6 and 7) alkylthio groups were used. That is, both (+)- and (-)-trans-diaryloxiranes could be obtained in excellent yields and moderate to good ee values under extremely mild conditions from the same chiral pool-derived reagents. A nonbonded interaction between the free OH in the ylides from sulfides (3, 6, and 7) and the carbonyl group of aldehydes controls the approach of the substrates to the ylidic carbon preferentially at one specified face and therefore leads to a more efficient asymmetric induction than that in the case of the ylide from methyl-protected hydroxylated sulfides 4, which cannot cause such an interaction. The same opposite asymmetric induction was also observed in the catalytic reaction with methyl-protected hydroxylated sulfide 4b and unprotected hydroxylated sulfide 3b.