Transformations initiated

The average ( ) in (5.6) is over many repetitions of the transformation initiated from an equilibrium ensemble of configurations at A = 0, with the same prescribed... 

The two articles in this current volume describe recent developments with small ring compounds which have not teen compiled in such a context before. T. Hirao discusses selective transformations initiated by transition derivatives in the construction of functionally substituted five-, six- and seven-membered rings as well as open-chair compounds. Cycloadditions onto methylene- and alkylidene-cyclopropane derivatives, described by A. Goti, F. M. Cordero and A. Brandi, not only yield products with spirocyclopropane moieties which can be desirable as such or as potential mimics of gem-dimethyl groupings, but also intermediates which can undergo further transformations with ring-opening of the cyclopropane units. 

Bruneau C (2004) Ruthenium Vinylidenes and Allenylidenes in Catalysis. 11 125-153 Bruneau C, D4rien S, Dixneuf PH (2006) Cascade and Sequential Catalytic Transformations Initiated by Ruthenium Catalysts. 19 295-326 Brutchey RL, see Fujdala KL (2005) 16 69-115... 

The amino group of 463 is transformed initially into carbamate compounds by treatment with several isocyanates. The carbamate intermediates were readily cyclized in base to give dihydrothieno[3,2-4]pyrimidines 464 (Equation 173) <1996MI597, 1995JOC1461>. 

Fortunately, as this chapter is written in January 2005, product and process development in the pharmaceutical industry appears to be entering a period of deep transformation, initially driven by recognition at the FDA that a higher technological standard was a desirable and achievable goal, and fueled by an intense desire for improvement on the part of many industrial scientists and engineers. 

Recently, evidence for this microbial transformation initiation strategy has also been seen for alkanes incubated in anaerobic cultures (Kropp et al., 2000 Rabus et al., 2001). In one case, a denitrifying bacterium was involved, while in the other case, the alkane was metabolized by a sulfate-reducing organism. Consistent with the hydrogen abstraction-fumarate addition mechanism (Fig. 17.11), succinate was found attached to the subterminal carbons of alkanes like hexane and dodecane ... 

One of the first significant advances in the chemistry of TT-allylpalladium complexes was the discovery that alkenes could be directly converted into the corresponding allyl complex by substitution into the allylic C—H bond. A variety of recipes have now been reported that can accomplish this transformation. Initially, palladium chloride17-23 or its more soluble forms, sodium or lithium tetrachloropalladate24-27 and bisacetonitrile palladium dichloride,28-30 in alcohol or aqueous acetic acid solvent were employed. The use of palladium trifluoroacetate, followed by counterion exchange with chloride, represents the mildest and most effective means available to accomplish this reaction.31... 

Stages of Transformation. The gradual character apparently represents stages of the transformation initiated by mechanical energy at different structural levels of the polymer. These stages are ... 

The transformations initiated by mechanical energy do not uniformly and necessarily pass through all three stages. The number and duration of the stages are determined by the nature and intensity of the mechanical stress. 

RNAi in larval schistosomes was only observed if dsRNA was administered at, or shortly after, the initiation of miracidial transformation. As the time between transformation initiation and the addition of dsRNA increased, the effectiveness of the treatment decreased by 24 h, dsRNA treatment was completely ineffective at reducing target transcript levels (Boyle et al., 2003). As noted earlier, both miracidial transformation and cercarial transformation involve complex outer tegumental membrane reorganizations it may be that the... 

At Ms temperature TiNi initiates a uniform (inhomogeneous) distortion of its lattice — through a collective atomic shear movement. The lower the temperature, the greater the magnitude of shear movements. As a result, between Ms and Mr temperature the crystal structure is not definable. In sharp contrast, other known martensitic transformations initiate a nonuniform (heterogeneous) nucleation at Ms and thereafter the growth of martensite is achieved by shifting of a two dimensional plane known as invariant plane [28] at a time. Thus, between Ms and Mr temperature the crystal structure is that of austenite and/or martensite . 

Shifting successfully away from a narrow and short-lived approach, however, opens up the potential for purchasing to become a valued and trusted partner for the other functions. A sustainable purchasing performance transformation initiates change that penetrates deep into the heart and mind of the organization. To be successful in the long term, it has to rest on four strong pillars ... 

E. V Gorobets, M. S. Miftakhov, F. A. Valeev, Tandem Transformations Initiated and Determined by the Michael Reaction, Russ. Chem. Rev. 2000, 69, 1001-1019. 

Cascade and Sequential Catalytic Transformations Initiated by Ruthenium Catalysts... 

Abstract Ruthenium holds a prominent position among the efficient transition metals involved in catalytic processes. Molecular ruthenium catalysts are able to perform unique transformations based on a variety of reaction mechanisms. They arise from easy to make complexes with versatile catalytic properties, and are ideal precursors for the performance of successive chemical transformations and catalytic reactions. This review provides examples of catalytic cascade reactions and sequential transformations initiated by ruthenium precursors present from the outset of the reaction and involving a common mechanism, such as in alkene metathesis, or in which the compound formed during the first step is used as a substrate for the second ruthenium-catalyzed reaction. Multimetallic sequential catalytic transformations promoted by ruthenium complexes first, and then by another metal precursor will also be illustrated. 

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