Hydrogen-atom transfer from water to free radicals can be mediated by aqua complexes of titanium(III) (see scheme). Asymmetric epoxidation in combination with [Cp2TiCl]/H2O-mediated reductive epoxide opening viewed as an alternative complementary stereoselectivity the hydroboration–epoxidation method for enantioselective synthesis anti-Markovnikov alcohols alkenes. Supporting information this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z600831_s.pdf or...

The polyhydroxyalkanoate (PHA) production process that uses mixed microbial cultures combined with main stream wastewater treatment plants (WWTPs) is a competitive integrated resource recovery in which non-oxygen electron acceptors can be used to enrich the PHA producer. Trials carried out operating are very scarce, and there no simulation tools available analyse feasibility of integrating two processes. This research presents novel analysis tool for techno-economic assessment value-added...

From a marine-derived strain of the fungus Emericella variecolor, varitriol (1), varioxirane (2), dihydroterrein (3), and varixanthone (4), besides known mold metabolites ergosterol, terrein, shamixanthone, tajixanthone hydrate, were identified. The chemical structures 1−4 established by means spectroscopic techniques some transformations. In NCI's 60-cell panel, (1) displayed increased potency toward selected renal, CNS, breast cancer cell lines. Varixanthone (4) showed antimicrobial activity.

Abstract The titanocene‐catalyzed cascade cyclization of epoxypolyenes, which are easily prepared from commercially available polyprenoids, has proven to be a useful procedure for the synthesis C 10 , 15 20 and 30 terpenoids, including monocyclic, bicyclic, tricyclic natural products. Both theoretical experimental evidence suggests that this takes place in nonconcerted fashion via discrete carbon‐centered radicals. Nevertheless, termination step process seems subjected kind water‐dependent...

BACKGROUNDClomifene citrate (CC) is accepted as the first-line method for ovulation induction (OI) in patients with polycystic ovary syndrome (PCOS) associated infertility owing to anovulation. Low-dose FSH has been reserved women failing conceive CC. In this RCT, we tested hypothesis that pregnancy rate (PR) and live birth rates (LBR) are higher after OI low-dose than CC treatment.

Abstract The vast range of reactions mediated by titanocene monochloride (Cp 2 TiCl, the Nugent reagent) in organic synthetic chemistry is reviewed. power reagent demonstrated its ability to promote and/or catalyse several efficient transformations under mild reaction conditions presence functional groups, an environmentally friendly manner and with use simple experimental procedures.

The development of Green Chemistry inevitably involves the green reagents. In this review, we highlight that Cp2TiCl is a reagent widely used in radical and organometallic chemistry, which shows, if not all, at least some 12 principles summarized for Chemistry, such as waste minimization, catalysis, safer solvents, toxicity, energy efficiency, atom economy. Also, complex has proved to be an ideal C–C C–O bond forming reactions, reduction, isomerization, deoxygenation reactions several...

[reaction: see text] A general procedure for the synthesis of both 12,6- and 12,8-eudesmanolides has been developed. The key step is titanocene-catalyzed radical cyclization accessible epoxygermacrolides. novel reagent 2,4,6-trimethyl-1-trimethylsilylpyridinium chloride, compatible with oxiranes capable regenerating Cp(2)TiCl(2) from Cp(2)Ti(Cl)H Cp(2)Ti(Cl)OAc, played an important role in catalytic cycle leading to exocyclic alkenes.

The Cp(2)TiCl-mediated rearrangement of 1,10-epoxy-11beta,13-dihydrocostunolide (4) was carried out using different solvents and additives to develop an expeditious procedure for the synthesis natural eudesmanolides via free-radical chemistry. In nonhalogenated THF, benzene, toluene transannular cyclization, initiated by homolytic opening oxirane ring, selectively led desired exocyclic alkene 5. When water added however, main product reduced eudesmanolide 8. Experiments with D(2)O confirmed...

Abstract The alkyne functional group is found in many bioactive natural products and the key to important chemical transformations developed over recent years. Moreover, allenes have recently gained relevance as versatile reagents organic synthesis. Mild, catalytic methods enable selective introduction of either or allene motifs into molecules are very valuable but, yet, quite scarce. We describe an extremely mild method for propargylation allenylation carbonyl compounds catalyzed by...

A bioinspired and sustainable procedure for the straightforward synthesis of (±)-aureol has been achieved in eight steps (14% overall yield) from epoxyfarnesol. The key are titanocene(III)-catalyzed radical cascade cyclization an epoxyfarnesol derivative a biosynthetically inspired sequence 1,2-hydride methyl shifts.

In the last two decades, titanocene monochloride has been postulated as a monoelectronic transfer reagent capable of catalyzing an important variety chemical transformations. this Perspective, our contributions to growing field research are summarized and analyzed. Especially known have in C–C bond formation reactions, hydrogen-atom from water radicals, isomerization well development catalytic cycle that subsequently allowed preparation great natural terpenes. It is also worth mentioning...

Abstract Many biologically active substances are composed of sesquiterpene units linked to aromatic structures, especially substituted phenols. Here, we describe an efficient synthetic approach this class natural product from commercially available in a short sequence. The key transformations involve allylic substitution reactions using palladium or copper catalyst and titanocene‐catalyzed epoxypolyene cyclization via radicals. polycyclic core structures accessed with high chemo‐...

Abstract Exocyclic allenes constitute useful building blocks in organic synthesis and have recently been identified as key intermediates the of natural products. Here first general method for most straightforward exocyclic reported to date is presented. This based on Barbier‐type cyclization propargyl halides catalyzed by titanium; a safe, abundant, ecofriendly metal. The reaction proceeds under mild conditions compatible with different functional groups provides good yields five‐, six‐,...

Selective Barbier-type allylations, benzylations and propargylations of aldehydes ketones can be carried out under extremely mild conditions employing titanocene(III) complexes as catalysts. In this way, chiral titanocene catalysts provided yields ranging from 50-80% optically active products.

The unprecedented homolytic opening of ozonides promoted and catalyzed by titanocene(III) is reported. This novel reaction proceeds at room temperature under neutral, mild conditions compatible with many functional groups provides carbon radicals suitable to form C-C bonds via both homocoupling cross-coupling processes. procedure has been advantageously exploited for the straightforward synthesis natural product brittonin A.

A catalytic and highly stereoselective synthesis of a common building block for the marine natural product puupehedione (1) its biologically more active 8-epimer is described. Our approach features copper-catalyzed allylic substitution reaction epoxyfarnesyl acetate diastereoselective titanocene-catalyzed epoxypolyene cyclization via radicals. The formal syntheses 1 2 are completed by ring closures to required benzodihydropyran units.

Der Transfer von Wasserstoffatomen Wasser auf freie Radikale kann durch Aqua-Komplexe Titan(III) vermittelt werden (siehe Schema). Die asymmetrische Epoxidierung kombiniert mit der [Cp2TiCl]/H2O-vermittelten reduktiven Epoxidöffnung bietet sich als Alternative komplementärer Stereoselektivität zur Hydroborierung-Epoxidierung für die enantioselektive Synthese Anti-Markownikoff-Alkoholen aus Alkenen an.

Journal Article A controlled study of human chorionic gonadotrophin induced ovulation versus urinary luteinizing hormone surge for timing intrauterine insemination Get access Antonio R. Martinez, Martinez 1 1To whom correspondence should be addressed Search other works by this author on: Oxford Academic PubMed Google Scholar Rob E. Bernadus, Bernadus Feja J. Voorhorst, Voorhorst 2Department Theory Medicine, Epidemiology and Biostatistics, Free University HospitalPO Box 7057, 1007 MB...

External quality assessment is essential in modern andrology laboratories. To assess the proficiency of laboratories participating an external programme (EQAP), limits for acceptable variability must be determined. Limits currently specified largely depend on criteria set by organizers individual EQAP schemes. The objective this study was to evaluate different described ISO 13528: 2005 calculating when applied basic semen analysis parameters.The data used were means and standard deviations...