Total synthesis of (+)-pederin. 1. Stereocontrolled synthesis of (+)-benzoylpedamide

(+)-Benzoylpedamide (5), a right half of (+)-pederin (1), was synthesized stereoselectively based on the newly developed method for the synthesis of 1,3-$\text{syn}$-and 1,3-$\text{anti}$-polyols.     

Synthesis of thromboxane A2 analogs—3 : (+)-Thiathromboxane A2

(+)-11a-methano-9,11-thiathiromboxane A₂(1) was synthesized from prostaglandin A₂ and prostaglandin E₂.     

Studies in macrolide synthesis: A highly stereoselective synthesis of (+)-(9S)-dihydroerythronolide a using macrocyclic stereocontrol

(+)-(9S)-Dihydroerythronolide A, 1, is prepared in 8 steps from macrolide 3 by exploiting the conformational preferences of the (5E,11E)-diene intermediate 2. The stereocontrolled introduction of the hydroxyl groups at C₆, C₁₁, and C₁₂ is achieved by osmylation, 2 → 13 and 15 → 1, while that at C₅ is obtained by a Zn(BH₄)₂ reduction, 13 → 14.     

(+)-O-萘基环状磷酰二胺酯的合成、晶体结构及绝对构型

合成了目标化合物(+)-O-萘基环状磷酰二胺酯,其结构由¹HNMR,³¹PNMR及元素分析确定,并在273K下进行了X射线衍射晶体结构分析.该化合物晶体属正交晶系,P2₁2₁2₁空间群,晶胞参数a=1.0028(4)nm,b=1.1406(4)nm,c=2.4455(8)nm,V=2.7971(18)nm₃,Z=4,Dc=1.212g/cm³,F(000)=1088,μ=0.129mm^-1.晶体的结构收敛最终偏离因子R和wR分别为0.0585和0.0827.Flackx参数为0.03(12).目标化合物中磷原子的绝对构型为S.     

Polyhydroxylated pyrrolizidines. Part 3: A new and short enantiospecific synthesis of (+)-hyacinthacine A2

(1R,2R,3R,7aR)-1,2-Dihydroxy-3-hydroxymethylpyrrolizidine (+)-Hyacinthacine A₂ 1 has been synthesized by Wittig's methodology using [(2′S,3′R,4′R,5′R)-3′,4′-dibenzyloxy-N-tert-butyloxycarbonyl-5′-tert-butyldiphenylsilyloxymethylpyrrolidin-2′-yl]carbaldehyde 3, prepared from a partially protected DMDP 2, and the appropriated ylide, followed by cyclization by an internal reductive amination process of the resulting unsaturated aldehyde 4 and total deprotection.     

Total synthesis of (+)-muconin

(+)-Muconin (1), isolated from the leaves of Rollinia mucosa (Jacq.) Baill. (Annonaceae), is a sequential THF/THP-possessing acetogenin that exhibits potent and selective in vitro cytotoxicity toward pancreatic and breast tumor cell lines. In this study, a new route was established for obtaining (+)-muconin (1) starting with (-)-muricatacin (2), a compound recently synthesized via the novel alpha-C-H hydroxyalkylation and alpha'-C-H oxidation of tetrahydrofuran.     

Stereoselective construction of a quaternary carbon substituted with multifunctional groups: application to the concise synthesis of (+)-ethosuximide

Synthetically useful β,γ-unsaturated carbonyl compounds having a quaternary carbon at the -position were prepared with high stereoselectivity by the reaction of a dienolate anion derived from ,β-unsaturated imide having a chiral auxiliary and electrophiles (ethyl acetate and allyl iodide as the C₂ and C₃ unit, respectively). This method was applied to a short asymmetric synthesis of (+)-ethosuximide.     

Cooperative effects in binuclear zirconocenes: Their synthesis and use as catalyst in propene polymerization

The mono- and bis-cyclopentadienyl compounds 1-(Cp″)-4-(CH₃)C₆H₄ (1) and 1, 4-(Cp″)₂C₆H₄ (2) (Cp″ = 3,4-dimethylcyclopenta-1,3-diene-1-yl) have been synthesized. The reactions of the lithium salts of 1 and 2 with CpZrCl₃ · dme (dme = dimethoxyethane) and Cp*ZrCl₃(CP* = C₅(CH₃)₅) yielded the mono- and bi-nuclear bridged zirconocenes 1-(Cp″ZrCpCl₂)-4-(CH₃)C₆H₄ (3), 1,4-(Cp″ZrCpCl₂)₂C₆H₄ (4) and 1,4-(Cp″ZrCp*Cl₂)₂C₆H₄ (5). When activated with methylaluminoxane (MAO), the mono- and bi-nuclear zirconocenes 3 and 4 catalyse the polymerization of propene. The influence of the catalyst composition on the polymerization kinetics and molecular weight is discussed.     

The synthesis, structural features and thermal behaviour of thiophene-containing dithiocarboxylate complexes of zinc(II)

The complexes [Zn₂(S₂CTR)₄] (T = 2,5-disubstituted thiophene, R = C₄H₉ (1), C₆H₁₃ (2), C₈H₁₇ (3), C₁₂H₂₅ (4) and C₁₆H₃₃ (5)) have been synthesized and their structural features investigated. Compared to the analogous dithiobenzoate complexes, the crystal structure determination of 2 revealed that the thiophene induces a “step-rod” chain pattern instead of the linear, rodlike structure found for the corresponding dithiobenzoates. Complexes 1–5 did not display mesophases under thermal conditions, but an irregular melting pattern was observed for 3 and 4.     

A convenient route to (+)-(9,11)-epithia-(11,12)-methano-thromboxane A2, from prostaglandin E2, methyl ester

(+)-(9,11)-Epithia-(11,12)-methano-thromboxane A₂ which is of great importance in thromboxane research, has been synthesized from prostaglandin E₂ methyl ester.     

单斜相WO_3的水热合成及其光催化性能的研究

利用水热合成法,以钨酸钠为钨源,硝酸为酸源,柠檬酸与酒石酸为辅助剂,制备了单斜相且形貌规整的WO_3。对WO_3样品进行了X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)及紫外可见漫反射(UV-vis-DR)分析,测试了样品的BET比表面积,考察了硝酸与钨原子物质的量比,柠檬酸、酒石酸与钨原子物质的量比对样品晶相与形貌的影响。结果表明,大量硝酸及羟基酸的加入都有利于WO_3单斜相的形成,当硝酸与钨原子的物质的量比为2.8∶1,羟基酸与钨原子的物质的量比为0.8∶1时,能够制得单斜相、形貌规整的WO_3样品。将WO_3与p型半导体物质CuCrO_2复合得到CuCrO_2-WO_3复合催化剂用于光催化分解水产氢的实验,高结晶度的单斜相WO_3具有较好的光催化性能。     

The octant rule: XXIII. antioctant effects in γ,δ -unsaturated ketones.

The and -benzyl derivatives (1 and 2, respectively) of (+)-camphor have been synthesized and are found to exert a strong influence on the circular dichroism n→π^* Cotton effects: 1: Δε³⁰¹_max -0.36 (n- heptane) and 2: Δε³⁰²_max +3.22, relative to camphor: Δε³⁰⁴_max +1.8 (n-heptane). Evidence for electric dipole transition moment coupling in these γ, δ -unsaturated systems is found in the n→π^* UV: 1: ε²⁹¹_max 84 (n-heptane) and 2: ε²⁸⁵_max 303, relative to camphor: ε²⁹⁰_max 25.     

Diastereoselective synthesis of a resolved secondary arsine complex: asymmetric synthesis of (R-(−)589-ethylmethylphenylarsine

The reaction of [R-(R,R)]-(+)₅₈₉-[(η⁵-C₅H₅){1,2-C₆H₄(PMePh)₂}Fe(NCMe)]PF₆ with (±)-AsHMePh in boiling methanol yields crystalline [R-[(R)-(R,R)]-(+)_{589)-[(η⁵-C5H5){1,2-C6H4(PMePh)2}Fe(AsHMePH)}PF₆, optically pure, in ca. 90% yield, in a typical second-order asymmetric transformation. This complex contains the first resolved secondary arsine. Deprotonation of the secondary arsine complex with KOBu^t at −65°C gives the diastereomerically pure tertiary arsenido-iron complex [R-[(R),(R,R)]]-[((η⁵-C₅H₅){1,2-C₆H₄(PMePh)₂}FeAsMePh] · thf, from which optically pure [R-[(S),(R,R)]]-(+)₅₈₉-[(η⁵-C₅H₅){1,2-C₆H₄(PMePh)₂}Fe(AsEtMePh)PF₆ is obtained by reaction with iodoethane. Cyanide displaces (R)-(−)₅₈₉-ethylmethylphenylarsine from the iron complex, thereby effecting the asymmetric synthesis of a tertiary arsine, chiral at arsenic, from (±)-methylphenylarsine and an optically active transition metal auxiliary.     

(S)-(+)-1-Methyl-2-(6,7,-dimethoxy-2,3-naphthalimido)ethyl trifluoromethanesulfonate as a fluorescence chiral derivatizing reagent for carboxylic acid enantiomers in high-performance liquid chromatography

A new triflate-type fluorescence chiral derivatizing reagent, (S)-(+)-1-methyl-2-(6,7-dimethoxy-2,3-naphthalimido)ethyl trifluoromethanesulfonate, [S-(+)-MDNE-OTf], has been developed for the determination of the enantiomers of carboxylic acids. By introducing the two methoxy groups on the naphthalimido ring moiety, the red shift in the fluorescence spectrum and a high resolution in reversed-mode separation of the diastereomers of chiral carboxylic acids have been achieved. The detection limits (S/N=3) with ultraviolet and fluorescence detection are 8 fmol (λ_max=283 nm) and 4 fmol (λ_ex=283 nm, λ_em=467 nm), respectively.     

Stereoselective synthesis of (+)-blastmycinone

(+)-Blastmycinone has been synthesized based on diastereoselective synthesis of (2R,3S)-2-hydroxy-3-(1-propenyl)heptanoic acid by the ester enolate Claisen rearrangement of (R)-(E)-1-methyl-2-heptenyl glycolate and stereoselective reduction of α-hydroxy ketone with Zn(BH₄)₂.     

Optically active coordination compounds---XLVIII. Synthesis, resolution and interconversions of isomers of tris-salicylatocobaltate(III)

Stable aqueous solutions of the green ion [Co(sa1)₃]³⁻ (sa1 = dianion, C₆H₄( )(CO ), of salicylic acid, 2-hydroxybenzoic acid) are obtained from [Co(NH₃)₅ C1]C1₂ and an excess of salicylic acid. Several salts, [C][Co(sa1)₃] have been characterized, where C = [Co(NH₃)₆]³⁺ and [M(en)₃]³⁺ (M = Co or Rh, EN = 1,2-diamino-ethane). By using (+)-[Rh(en)₃]³⁺, optical resolution via less soluble diastereoisomeric salts has been achieved, and isomerization and racemization have been studied. Resolved tris-malonatocobaltate(III) has been used as a model. A novel thermochromism (77-293 K) in solid Δ(+)-[Rhen₃]Λ[Co(sa1)₃ is described.     

Complexes of ruthenium(II) and -(III) with dimethylsulphoxide—III. Bis-iodo-tetrakis- dimethylsulphoxide ruthenium(II) and some other iodo complexes of ruthenium(II)

The ruthenium(II) complex [RuI₂(Me₂SO)₄] was synthesized and characterized. The Me₂SO ligands are all S-bonded. Reactions of RuI₂(Me₂SO)₄ with ligands containing P, N and S donor atoms have been carried out and the complexes obtained were characterized using different physical methods. [RuI₂L₄] (L= CH₃CN, Me₂SO and py), [RuI₂(CH₃CN)₂(PPh₃)₂] and [RuI₂(CS)(PPh₃)₃] have been synthesized using RuI₃ as the source material and characterized as above.     

First synthesis of (+)-alpha- and (+)-gamma-polypodatetraenes

First synthesis of (+)-alpha-polypodatetraene (1) and (+)-gamma-polypodatetraene (2) was achieved from (+)-albicanol (6) and (-)-drimenol (8), respectively. The absolute structure of natural (+)-2 was established to be (5S,9S,10S)-polypoda-7,13(E),17(E),21-tetraene.     

Highly stereoselective reduction of methyl ketone complexes of the chiral Lewis acid [(η-C5H5)Re(NO)(PPh3)] by K(s-C4H9)3BH; synthesis of optically active secondary alcohols and derivatives

Reaction of optically active ketone complexes (+)-(R)-[(η⁵-C₅H₅)Re(NO)-(PPh₃)(η¹-O=C(R)(CH₃)]⁺ BF₄⁻ (R = CH₂CH₃, CH(CH₃)₂m C(CH₃)₃, C₆H₅) with K(s-C₄H₉)₃BH gives alkoxide complexes (+)-(RS)-(η⁵-C₅H₅)Re(NO)(PPh₃)-(OCH(R)CH₃) (73–90%) in 80–98% de. The alkoxide ligand is then converted to Mosher esters (93–99%) of 79–98% de.     

Design and synthesis of hybrid solids based on the tetravanadate core toward improved catalytic properties

Five inorganic–organic hybrid vanadates based on tetravanadate cores, transition metals and N-donor ligands have been designed and synthesized under hydrothermal conditions, namely, [Zn(eIM)_3]_2V_4O_(12)(1), [Zn(pIM)_3]_2V_4O_(12)H_2O(2), [Zn(ipIM)_3]_2V_4O_(12)(3), [Co(e IM)_3]_2V_4O_(12)H_2O(4), [Cu(eIM)_2(H+2O)]_2V_4O_(12)(_5)(eIM = 1-ethylimidazole, p IM = 1-propylimidazole, ip IM = isopropylimidazole). All compounds were fully characterized by single-crystal XRD, powder XRD, elemental analysis, TGA, and FT-IR spectroscopy.The hybrid zinc vanadates(1–3) and cobalt vanadate(4) exhibit interesting 2D folded structures and the hybrid copper vanadate(5) presents a 1D chain configuration. All compounds can catalyze olefin epoxidation reactions when using TBHP(TBHP = tert-butyl hydroperoxide) as an oxidant in acetonitrile.The introduction of transition metal ions into tetravanadate cores not only improved the catalytic activity but also fulfilled the heterogeneous catalytic behavior. 1–5 all exhibit extraordinary efficiency in converting olefins to the corresponding epoxides with high conversion and selectivity(particularly,conv. up to 97.1%, sele. up to 100% for 1). Leaching test was also carried out to prove the heterogeneous behavior.