4208-61-1

Background: Podophyllotoxin is a natural lignan which possesses anticancer and antiviral activities. Etoposide and teniposide are semisynthetic glycoside derivatives of podophyllotoxin and are increasingly used in cancer medicine. Objective: The present work aimed to design and synthesize a series of 2, 4, 5-trideoxyhexopyrano-sides derivatives of 4’-demethylepipodophyllotoxin as novel anticancer agents. Methods: A divergent de novo synthesis of 2, 4, 5-trideoxyhexopyranosides derivatives of 4’-demethylepipodophyllotoxin has been established via palladium-catalyzed glycosylation. The abili-ties of synthesized glycosides to inhibit the growth of A549, HepG2, SH-SY5Y, KB/VCR and HeLa cancer cells were investigated by MTT assay. Flow cytometric analysis of cell cycle with propidium iodide DNA staining was employed to observe the effect of compound 5b on cancer cell cycle. Results: Twelve D and L monosaccharide derivatives 5a-5l have been efficiently synthesized in three steps from various pyranone building blocks employing de novo glycosylation strategy. D-monosaccharide 5b showed the highest cytotoxicity on five cancer cell lines with the IC50 values ranging from 0.9 to 6.7 μM. It caused HepG2 cycle arrest at G2/M phase in a concentration-dependent manner. Conclusion: The present work leads to the development of novel 2, 4, 5-trideoxyhexopyranosides derivatives of 4’-demethylepipodophyllotoxin. The biological results suggest that the replacement of the glucosyl moiety of etoposide with 2, 4, 5-trideoxyhexopyranosyl is favorable to their cytotoxic-ity. D-monosaccharide 5b was observed to cause HepG2 cycle arrest at the G2/M phase in a concen-tration-dependent manner.

A chiral 2,2′-bipyridine ligand (1) bearing α,α′-trifluoromethyl-alcohols at 6,6′-positions was designed in five steps affording either the R,R or S,S enantiomer with excellent stereoselectivities, i.e. 97% de, >99% ee and >99.5% de, >99.5% ee, respectively. The key step for reaching high levels of stereoselectivity was demonstrated to be the resolution of the α-CF3-alcohol using (S)-ibuprofen as the resolving agent. An initial application for the 2,2′-bipyridine-α,α′-CF3-diol ligand was highlighted in the ZnII-catalyzed asymmetric ethylation reaction of aromatic, heteroaromatic, and aliphatic aldehydes. Synergistic electron deficiency and steric hindrance properties of the newly developed ligand afforded the corresponding alcohols in good to excellent yields (up to 99%) and enantioselectivities (up to 95% ee). As observed from single crystal diffraction analysis, the complexation of the 2,2′-bipyridine-α,α′-CF3-diol ligand generates an unusual hexacoordinated ZnII.

The invention relates to a method for preparing 2-acyl furan. The method is characterized by comprising the following steps: (1) controlling the temperature to -10-40 DEG C, and adding 70-98% of a water phase or 10-90% of a mixed liquid of the water phase and an organic phase, 0.0001-2.0% of an osmium compound and 0.001-5.0% of an amine compound into a reaction container so as to obtain a reactionliquid; (2) feeding the reaction liquid into a sealed reactor, and performing gas exchange to provide an aerobic environment for reactions; (3) adding 1-(2-furyl)-1-alkyl methanol into the sealed reactor, and controlling the pressure to 0-20MPa and the temperature to 0-200 DEG C for 1-74 hours; and (4) after the reaction is stopped, performing cooling to the room temperature, performing pressurerelease to the barometric pressure, adding sodium hydrogen sulfate and acetic acid, performing extraction, and performing organic phase vacuum distillation refining, so as to obtain a 2-acyl furan product. The method has the advantages that technical and economical defects of a conventional synthesis route can be avoided, process procedures can be reduced, consumption and emission can be reduced,the energy consumption and the cost can be lowered, and the method is applicable to capacity increase industrial production.

A series of bifunctional spiro ligands bearing “carboxamide–phosphine oxide” groups and ethylzinc carboxamidates from these ligands as catalysts for Et2Zn additions to aldehydes were reported. Excellent yields were obtained with moderate ee′s in Et2Zn additions to benzaldehyde derivatives, implying effectiveness of our newly designed catalytic structures as well as mediocre stereocontrol by these chiral ligands. Possible transition states were suggested based on the crystal structures of two ligands.

Efficient and modular syntheses of chiral 2-(2-hydroxyaryl)alcohols (HAROLs), novel 1,4-diols carrying one phenolic and one alcohol hydroxyl group, have been developed which led to generation of a small library of structurally diverse HAROLs in enantiomerically pure form. Of the different HAROLs examined, a HAROL based on the indan backbone exhibited the highest activity and enantioselectivity in the 1,2-addition of certain organometallic compounds to aldehydes in the presence of Ti(OiPr)4 (up to 97% y, 88% ee) and performed as a hydrogen-bond donor organocatalyst in the Morita-Baylis-Hillman reaction, promoted by trialkylphosphines.

ortho Substituted (diphenylphosphoryl)-, (diphenylphosphorothioyl)- and (diphenylphosphoroselenoyl)-phosphinic amides o-C6H 4(P(X)Ph2)(P(O)NiPr2) (X = O (20a), S (20b), Se (20c)) were synthesized by ortho directed lithiation of N,N-diisopropyl-P,P-diphenylphosphinic amide (Ph2P(O)N iPr2) followed by trapping with Ph2PCl and subsequent oxidation of the o-(diphenylphosphine)phosphinic amide (19) with H2O2, S8 and Se. The reaction of the new mixed-donor bidentate ligands with zinc dichloride afforded the corresponding complexes [ZnCl2(P(X)Ph2)o-C6H 4(P(O)NiPr2)] (21a-c). The new compounds were structurally characterized in solution by nuclear magnetic resonance spectroscopy and in the solid-state by X-ray diffraction analysis of the ligand (20b) and the three complexes (21a-c). The X-ray crystal structure of 20b suggests the existence of a PO→P(S)-C intramolecular nonbonded interaction. The natural bond orbital (NBO) analysis using DFT methods showed that the stabilization effect provided by a nO→σ* P-C orbital interaction was negligible. The molecular structure of the complexes consisted of seven-membered chelates formed by O,X-coordination of the ligands to the zinc cation. The metal is four-coordinated by binding to the two chlorine atoms showing a distorted tetrahedral geometry. Applications in catalysis revealed that hemilabile ligands 20a-c act as significant promoters of the addition of diethylzinc to aldehydes, with 20a showing the highest activity. Chelation of Et2Zn with 20a was evidenced by NMR spectroscopy.

We report a novel catalytic system for the activation of diorganozinc reagents. We assumed that the nucleophilic activation of diethylzinc should be efficiently performed by simple alkali metal salts. Indeed, the combination of sodium salts and 15-crown-5 significantly accelerates the rate of diethylzinc addition to benzaldehyde under mild conditions. The activity of the catalytic system strongly depends on the nature of the anion, decreasing in the order I->Br->Cl->F-. Under the optimized reaction conditions, various aryl, hetero aryl, and aliphatic aldehydes were converted with diethylzinc and the corresponding product was obtained in excellent yields. The first X-ray absorption spectroscopy measurements on such type of reactions provide initial insights that support the proposed catalytic cycle and suggest the formation of a zincate complex.

The addition of diethylzinc to aromatic, heteroaromatic, and aliphatic aldehydes at room temperature is efficiently catalyzed by 1-7 mol% tetrabutylphosphonium chloride. The corresponding addition products are obtained in good to excellent yields of up to 99%. Moreover, polymer bond phosphonium salts can be used to catalyze this reaction with excellent recovery of the polymer bond catalyst up to three cycles. The application of chiral bifunctional phosphonium salts revealed a remarkable counter anion effect. Changing the anion, the activity of the tetrabutylphosphonium salt decreased in the order Cl- > Br- > I- ≈ TsO- > BF4- ≈ PF6-. However, the nature of the cation had also significant influence. Tetraalkyl-ammonium chlorides showed similar activity compared to phosphonium chlorides, while alkaline metal chlorides proved to be considerably less active. Georg Thieme Verlag Stuttgart.

The hexamethylbenzene-ruthenium(ii) dimer [{RuCl(μ-Cl) (η6-C6Me6)}2] 1 and the mononuclear bis(allyl)-ruthenium(iv) complex [RuCl2(η 3:η2:η3-C12H 18)]2, associated with base and a hydrogen donor, were found to be active catalysts for the selective reduction of the CC bond of allylic alcohols both in organic and aqueous media. The process, which proceeds in a one-pot manner, involves a sequence of two independent reactions: (i) the initial redox-isomerization of the allylic alcohol, and (ii) subsequent transfer hydrogenation of the resulting carbonyl compound. The highly efficient transformation reported herein represents, not only an illustrative example of auto-tandem catalysis, but also an appealing alternative to the classical transition-metal catalyzed CC hydrogenations of allylic alcohols. The process has been successfully applied to aromatic as well as aliphatic substrates affording the corresponding saturated alcohols in 45-100% yields after 1.5-24 h. The best performances were reached using (i) 1-5 mol% of 1 or 2, 2-10 mol% of Cs2CO3, and propan-2-ol or (ii) 1-5 mol% of 1 or 2, 10-15 equivalents of NaO2CH, and water. The catalytic efficiency is strongly related to the structure of the allylic alcohol employed. Thus, in propan-2-ol, the reaction rate essentially depends on the steric requirement around the CC bond, therefore decreasing with the increasing number of substituents. On other hand, in water the transformation is favoured for primary allylic alcohols vs. secondary ones.

The decarboxylative Claisen rearrangement (dCr) reaction of 1-(furan-2-yl)ethyl 2-tosylacetate afforded 2-ethylidene-3-(tosylmethyl)-2,3-dihydrofuran. Reaction of the dearomatised heterocycle with a variety of electrophiles gave addition products with excellent syn-diastereoselectivity. The furanol adducts were then utilised as functionalised scaffolds for a series of subsequent transformations.

A simple and highly efficient method for the selective reduction of the C=C bond in allylic alcohols has been developed using the ruthenium(ii) catalyst [{RuCl(μ-Cl)(η6-C6Me6)}2]. The Royal Society of Chemistry.

Ni(acac)2 catalyzes homoallylation of aldehydes with 1,3-dienes in the presence of triethylborane. Triethylborane serves as a reducing agent delivering a formal hydride to the C2 position of 1,3-dienes, thus generating a formal homoallyl anion species and enabling the novel homoallylation of aldehydes. The reaction proceeds smoothly at room temperature in the absence of any phosphane or nitrogen ligands and is highly regioselective and stereoselective for a wide variety combination of aldehydes and 1,3-dienes: e.g., isoprene and benzaldehyde combine to give a mixture of anti- and syn-1-phenyl-3-methyl-4-penten-1-ol (2.2) in a ratio of 15:1 in 90% yield. Under the conditions, sterically congested aliphatic aldehydes and ketones show low yields. In such cases, diethylzinc serves as a substitute for triethylborane and yields the expected products in good yields with similarly high regio- and stereoselectivity. 1,3-Cyclohexadiene is one exception among 24 kinds of dienes examined and undergoes allylation (not homoallylation) selectively.

Regio- and stereoselective homoallylation of saturated aldehydes and ketones to give biohomoallyl alcohols 1,3-anti-1 is achieved with [Ni(acac)2] (cat.) and Et2Zn [Eq. (a)]. This new catalyst system thus complements the previously reported combination of [Ni(acac)2] with Et3B, which offers advantages in the homoallylation of unsaturated and aromatic aldehydes. acac = acetylacetonato.

The behaviour of furyl-2-oxirane in some nucleophilic ring opening reactions was studied.

Thermolysis of the 4-(o-toluoyloxy)-1,3-dioxolanes 4 leads to the furans 6/7 which, via Grignard reaction, can be converted into the alcohols 8/9.Subsequent dehydratization affords the olefins 10/11, e.g. rosefuran (10a).

The effect of steric crowding at the carbonyl carbon of some alkyl 2-furyl ketones, 2-Fur-CO-R (R = Et, i-Pr, and t-Bu), on the reaction with alkyl Grignard reagents, R'MgX (R' = Me, i-Pr, and t-Bu), has been studied.The effect of the size of the alkyl group of the Grignard reagent was also considered.When MeMgI reacts with the ketones only 1,2-addition products are formed.Reactions with i-PrMgCl and t-BuMgCl give considerable amounts of 1,4- and 1,6-addition products besides 1,2-addition.The primary conjugate addition products are easily oxidized to alkyl substituted alkyl 2-furyl ketones and 2-(5H)-furanones when exposed to air.Further, the i-Pr reagent gives reaction products formed by reduction of the carbonyl group.An increase in the amount of conjugate addition products is observed when the size of the alkyl group in the substrate or that of the alkyl group of the reagent is increased.Possible reaction mechanism are discussed.

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