Inversion of configuration, and

Furthermore, the catalytic allylation of malonate with optically active (S)-( )-3-acetoxy-l-phenyl-1-butene (4) yields the (S)-( )-malonates 7 and 8 in a ratio of 92 8. Thus overall retention is observed in the catalytic reaction[23]. The intermediate complex 6 is formed by inversion. Then in the catalytic reaction of (5 )-(Z)-3-acetoxy-l-phenyl-l-butene (9) with malonate, the oxidative addition generates the complex 10, which has the sterically disfavored anti form. Then the n-a ir rearrangement (rotation) of the complex 10 moves the Pd from front to the rear side to give the favored syn complex 6, which has the same configuration as that from the (5 )-( )-acetate 4. Finally the (S)-( )-mal-onates 7 and 8 are obtained in a ratio of 90 10. Thus the reaction of (Z)-acetate 9 proceeds by inversion, n-a-ir rearrangement and inversion of configuration accompanied by Z to isomerization[24]. 

The reaction of diethyl tartrate with sulfur tetrafluonde at 25 °C results in replacement of one hydroxyl group, whereas at 100 °C, both hydroxyl groups are replaced by fluonne to form a,a -difluorosuccinate [762] The stereochemical outcome of the fluonnation of tartrate esters is retention of configuration at one of the chiral carbon atoms and inversion of configuration at the second chiral center [163,164, 165] Thus, treatment ofdimethyl(+)-L-tartrate with sulfur tetrafluonde gives dimethyl meso-a,a difluorosuccinate as the final product [163, 164], whereas dimethyl meso tartrate is converted into a racemic mixture of D- and L-a,a -difluorosuccmates [765] (equation 80)... 

The enantiomerization of phenoxyalkanoic acids containing a chiral side chain has been studied in soil using (Buser and Muller 1997). It was shown that there was an equilibrium between the R- and S- enantiomers of 2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) and 2-(2,4-dichlorophenoxy)propionic acid (DCPP) with an equilibrium constant favoring the herbicidally active f -enantiomer. The exchange reactions proceeded with both retention and inversion of configuration at the chiral sites. 

In organometallic compounds of the form RR R"C—M, pretty well the whole spectrum of bonding is known from the essentially covalent, via the polar-covalent, RR R"C, —M4+, to the essentially ionic, RR R"CeM . In their reactions, predominant retention, racemisation, and inversion of configuration have all been observed the outcome in a particular case depending not only on the alkyl residue, but also on the metal, and particularly on the solvent. Even with the most ionic examples it seems unlikely that we are dealing with a simple carbanion thus in the reaction of EtI with [PhCOCHMe]6 M , the relative rates under analogous conditions are found to differ over a range of 104 for M = Li, Na and K. 

Under this term we shall consider only nucleophilic attack at the group IVg metal, the transition metal behaving as a leaving group. Nucleophiles may cleave the M -M,vb bond with both retention and inversion of configuration at the group... 

Stereospecific reaction (Section 7.13) Reaction in which stereoisomeric starting materials give stereoisomeric products. Terms such as syn addition, anti elimination, and inversion of configuration describe stereospecific reactions. 

As in substitution at carbon, stereochemical and kinetic data provide the means of differentiating between these two possibilities. The stereochemical data are examined first. Substitution at silicon leads to both retention and inversion of configuration and the stereochemical outcome depends upon the nature of the leaving group, the nucleophile, solvent, complexing agents and whether or not the silicon is part of a ring. 

Both retention of configuration and inversion of configuration have been observed in these electrophilic substitutions. The kinetic form of substitutions proceeding as in reactions (4) and (5) should be second-order overall, first-order in substrate and first-order in electrophile, when the two reactants are present in dilute solution at the same order of concentration. 

C. Only product K shows retention of configuration at one chiral center and inversion of configuration at the other chiral center. 

L-Rhodinose (174) was prepared from the readily available L-rhamnose.269 The method required deoxygenation of C-2 and C-3 and inversion of configuration at C-4 (Scheme 56). Oxidation of 187 with ruthenium dioxide-IOj, followed by reduction of the keto groups with lithium aluminum hydride yielded the alcohol 188. After protection as the benzyl derivative, an alkenic linkage was... 

Several different nucleophilic displacement reactions of ring substituents were utilized in the synthesis of 3-azido-oxetane-2-carboxylates (Scheme 12) <2001TL4247>. The triflate ester 66, prepared from the corresponding trans-/3-hydroxy ester and triflic anhydride, was displaced by reaction with sodium azide, and inversion of configuration, to... 

Although each pair of reactions is chemically matched their reaction mechanisms are quite different. The first member of each pair, 21 and 23, follow sequential kinetic pathways involving ternary complexes and inversion of configuration [88,89]. They seem to proceed by single displacement mechanisms. Their chemically matched... 

The reactions of HO and 02 - with alkyl halides exhibit the same general pattern (Scheme 16), with second-order kinetics and inversion of configuration. Radicals are not detected in the reactions with hydroxide ion, which indicates that there probably is not a discrete SET step, but rather that the transfer of the entering and leaving groups is synchronous with a single-electron shift. 

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