- Alkylaluminum-complexed zirconocene hydrides: Identification of hydride-bridged species by NMR spectroscopy
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Reactions of unbridged zirconocene dichlorides, (RnC 5H5-n)2ZrCl2 (n=0, 1, or 2), with diisobutylaluminum hydride (HAI'Bu2) result in the formation of tetranuclear trihydride clusters of the type (RnC5H 5-n)2Zr(μ-H)3(Al iBu2)3(μ-CI) 2, which contain three [Al iBu2] units. Ring-bridged ansa-zirconocene dichlorides, Me2E(RnC5H 4-n)2ZrCl2 with E=C or Si, on the other hand, are found to form binuclear dihydride complexes of the type Me2E(R nC5H4-n)2Zr(CI)(μ-H) 2Al iBu2 with only one [AIBu2] unit. The dichotomy between unbridged and bridged zirconocene derivatives with regard to tetranuclear versus binuclear product formation is proposed to be connected to different degrees of rotational freedom of their C5-ring ligands. Alkylaluminum-complexed zirconocene dihydrides, previously observed in zirconocene-based precatalyst systems activated by methylalumoxane (MAO) upon addition of HAI'Bu2 or Al iBu3, are proposed to be species of the type Me2Si(ind)2Zr(Me)(μ-H) 2Al iBu2, stabilized by interaction of their terminal Me group with a Lewis acidic site of MAO.
- Baldwin, Steven M.,Bereaw, John E.,Brintzinger, Hans H.
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p. 17423 - 17433
(2009/06/08)
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- Inhibitors of histone deacetylase
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The invention relates to the inhibition of histone deacetylase. The invention provides compounds and methods for inhibiting histone deacetylase enzymatic activity. The invention also provides compositions and methods for treating cell proliferative diseases and conditions.
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- Pyronin antibacterials, process and novel intermediates thereto
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The present invention provides convergent processes for preparing myxopyronins and corallopyronins, compounds useful as antibacterial therapeutics. The present invention also provides novel compositions of matter which are useful for the preparation of pyronin antibiotics.
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- Pyronin antibacterials, process and novel intermediates thereto
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The present invention provides convergent processes for preparing myxopyronins and corallopyronins, compounds useful as antibacterial therapeutics. The present invention also provides novel compositions of matter which are useful for the preparation of pyronin antibiotics.
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- Aminediol protease inhibitors
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Novel aminediol compounds, pharmaceutical compositions containing these compounds, and methods of using these compounds in inhibiting retroviral protease, particularly useful in the treatment and/or prevention of HIV infection (AIDS).
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- General method for preparation of sphingosine bases and their analogues
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Described herein is a novel method of preparing selectively diastereomers of sphingosine bases and their analogues of general formula (1a) or (1b) STR1 where R is an aliphatic or aromatic substituent containing a straight, branched or cyclic chain, which may include one or several heteroatoms as chain members and one or several functional groups as substituents. The method comprises the steps of:a) converting a starting material into an intermediate product in the form of α,β-unsaturated ketone having the general formula (4a) or (4b) STR2 where R is as defined above and PG are any protecting groups compatible with the method,b) reducing said α,β-unsaturated ketone to an aminoalcohol with DIBAL in toluene to obtain selectively an anti-diastereomer, andc) removing the protecting groups to obtain the free sphingosine base or its analogue according to formula (1a) or (1b).
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- Prostaglandins E and anti-ulcers containing same
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The novel 13,14-dihydro-15-keto prostaglandins E of the invention have remarkable preventive effects against ulcers. Further, the novel 13,14-dihydro-15-keto-prostaglandins E of the invention have an advantage that they have none of side effects which prostaglandin E intrinsically has, or can remarakably reduce such effects of the prostaglandin E. Therefore, the novel 13,14-dihydro-15-keto prostaglandins E of the invention are effective for animal and human use for treatment and prevention of ulcers, such as duodenal ulcer and gastric ulcer.
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- 1,3-dioxanes
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The invention concerns novel, pharmaceutically useful 1,3-dioxane alkanoic and alkenoic acid derivatives of the formula I in which the groups at positions 2, 4 and 5 of the 1,3-dioxane ring have cis-relative stereochemistry, Y is ethylene or vinylene, n is 1-4, Z is hydrogen or hydroxy, and X is a pyridine containing group (as defined hereinafter); and the pharmaceutically acceptable salts thereof. The invention also includes processes for the manufacture and use of the acid derivatives as well as pharmaceutical compositions for therapeutic use in one or more of a variety of diseases such as ischaemic heart disease, cerebrovascular disease, asthmatic disease and/or inflammatory disease.
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