Organometallics esters

The resolution procedure applies to racemic organometallic esters and to the esters of a thianucleoside, for the preparation of pure enantiomers of an antiviral agent (2, 3 -dideoxy-5-fluoro-3 -thiacytidine) (eq 7). ... 

Initial boiling point The titanate or zirconate selected is a liquid ester with an initial boiling point (IBP). For in situ exfoliation, the initial contact of the organometallic ester with the polymer should be below the IBP of the titanate, which must be solvated into the heat sink of the polymer before the temperatures are raised to process temperatures. This usually means adding the titanate to the extruder hopper at room temperature and then allowing a transition up in temperature over the next two or three zones where the filler would also be present. Otherwise, the functionality of the titanate will be significantly diminished. 

Schut, J. (1996) Organometallic esters enhance recycling of PET/PC blends. Plastics Formulat. Compound. 

Schut, J. H. (1996) "Organometallic esters enhance PET/PC blends," Plast World,... 

Although used primarily as adhesion promoters, certain organometallic esters (titanates, zirconates, aluminates, zircoalmninates) and in some cases even silanes are used at catal)rtic levels in filled or reinforced epoxy resins to modify viscosity and achieve novel compositions. 

Application of 7r-allylpalladium chemistry to organic synthesis has made remarkable progress[l]. As deseribed in Chapter 3, Seetion 3, Tt-allylpalladium complexes react with soft carbon nucleophiles such as maionates, /3-keto esters, and enamines in DMSO to form earbon-carbon bonds[2, 3], The characteristie feature of this reaction is that whereas organometallic reagents are eonsidered to be nucleophilic and react with electrophiles, typieally earbonyl eompounds, Tt-allylpalladium complexes are electrophilie and reaet with nucleophiles such as active methylene compounds, and Pd(0) is formed after the reaction. 

R Cu, or litliium or magnesium homocuprates RfCuM fM = Li, MgX), are fre-quently used, but a number of catalytic processes have also been developed. These processes nornnally utilize a catalytic amount of a copper salt CuY and a stoichiometric amount of an organometallic reagent R M IM = Li, MgX, ZnX, etc.). Hie leaving groups used include balides, esters, sulfonates, and epoxides, among others. 

Organometallics bearing esters fEq. 4.102 / ° dienes fEq. 4.1031, or oxygen funcdons fEq. 4.104/ " give nitroalkenes funcdonalized by these groups. 

The most common reactions of carboxylic acid derivatives are substitution by water (hydrolysis) to yield an acid, by an alcohol (alcoholysis) to yield an ester, by an amine (aminolysis) to yield an amide, by hydride ion to yield an alcohol (reduction), and by an organometallic reagent to yield an alcohol (Grignard reaction). 

One of the most general preparative routes to allyl- and 2-butenylboranes involves the reaction of an allylic organometallic species and an electrophilic borylating reagent. Various esters of allylboronic acid have been prepared in this way2,4-5. 

Preparation of the appropriate optically active sulfmate ester is initially required for reaction with a Grignard or other organometallic reagent. If the method is to produce homochiral sulfoxides, the precursor sulfmate ester must be optically pure. An exception to this statement occurs if the reaction yields a partially racemic sulfoxide which can be recrystallized to complete optical purity. 

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