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    Highly diastereoselective conjugate addition of organocuprate to acyclic E- and Z-enones: Reversal Stereoselectivity under kinetic and thermodynamic conditions
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    Products with 2′-5′-linkages and Rp configurations result from the stereoselective UO-catalyzed oligomerization of the adenosine derivative 1, although the starting monomer was used as a mixture of diastereomers. The high regio-and stereoselectivity observed here is rarely encountered except in enzymatic reactions.
    Diastereomer
    Derivative (finance)
    Citations (25)
    Abstract Benzalcyanoacetamides were designed and synthesized as reversible thiol conjugate addition acceptors. These thia‐conjugate additions can rapidly and reversibly achieve equilibrium under aqueous conditions at neutral pH. Kinetic studies show that electron‐withdrawing groups at the 4‐position of the phenyl ring of the benzalcyanoacetamides promote the conjugate addition at equilibrium. Dynamic thiol exchange of these conjugate acceptors is faster than singly activated α,β‐unsaturated carbonyl compounds. These thia‐conjugate additions can be assembled as potentially useful components in dynamic combinatorial chemistry.
    Conjugate
    Thiol
    Aqueous medium
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    Allyltitanocene complexes can be generated by reacting pentafulvenes with DIBAL-H and Cp2TiCl2. Their coupling with aldehydes affords homoallylic alcohols in a highly regio- and stereoselective manner. The potential of this method for the stereoselective synthesis of cyclopentane derivatives is illustrated.
    Cyclopentanes
    Surface Modification
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    Three types of Sb~Ⅲ reagents were studied.They are:(1)the compounds containing mer- capto group,(2)Caille and Viel reagents and(3)the compounds containing two phenolic groups in adiacent positions. It was shown experimentally that the first two types of reagents give reactions with very low selectivities.Moreover,the selectivities could not be improved by merely varying the structure of the organic compounds. The diphenolic compounds seem to be the most hopeful reagents for Sb~Ⅲ.Their reactions are considerably selective.Several classes of coloured compounds containing two phenolic groups in adjacent positions were prepared.Some of them were found to be satisfactory reagents for Sb~Ⅲ.
    Functional group
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    A remarkably stereoselective reduction of a γ-hydroxyketone with two equiv. of lithium triethylborohydride has been observed and this effect has been suggested to originate from 'chelation control'; the reaction has been utilised in a short stereoselective synthesis of ancistrofuran.
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    Objective To evaluate the stability of the total bile acid reagent after opening the improved bottles.Methods We analyzed the total bile acid reagents in automatic biochemistry respectively by using the common reagent bottles and the improved reagent bottles.Observe daytime variation of CV and trend changes of high,medium mixed complex-value serum and reagent blank test results.Then t test was applied.Results (1)The change trend of the improved reagent bottles was significantly slower than that of the common reagent bottles,(2)The total deviations of common reagent bottles before and after monitoring were-20.37% and-22.09% respectively.Total deviations of the improved reagent bottles were 3.77% and-1.16% respectively,(3)The daytime variations of the common reagent bottles in complex-value were 9.27% and 9.32% respectively;the improved reagent bottles were 3.38% and 2.03% respectively;(4)The reagent blank with improved reagent bottles decline significantly slower than common reagent bottles;(5)The measured result of t test of the two kinds reagent bottles in the monitoring period was t=4.889,P0.01,the result there was significantly different.Conclusion The impvored reagent bottles have good performance to slow down the decay of total bile acid reagentand,and it′s suitable for extending the period of reagents′ validity.It can significantly reduce daytime variation.
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    Folin reagent was one of the most important reagents in protease determination. The differences between Folin reagent from laboratory and Folin reagent sold were studied. The results showed that there was not significant difference between the absorbance of Folin reagent from lab replaced 30d and Folin reagent sold (p<0.05). The RSD of Folin reagent from lab was between 0.3and 1.67, and Folin reagent sold between 0.63 and 1.49. The precision of them was both higher. The maximum absorption wave length of the chromogenic agent of Folin reagent was with 736-755. And there was no significant difference of the value of the same sample protease between both Folin reagent (p<0.05). Folin reagent from lab based on GB/T23527-2009 was perfect.
    Chromogenic
    Absorbance
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