Replacement with rearrangement

The retention times for solutes A and B are replaced with their respective capacity factors by rearranging equation 12.10... 

The benzyl 1,2,4-thiadiazolium salt 59 can be isomerized to the 5-imino-l,2,4-thiadiazolidine 60 when treated with a strong base like potassium /-butoxide (Equation 17) <1997ZOR1728>. If the 2-substituent is replaced with a tosylmethyl group and the 5-position substituent is a diphenylamino in place of an aniline such as compound 61, then a rearrangement occurs to give an imidazole 62 (Equation 18) <1997ZOR1728>. 

The term hetero rearrangement is not limited to those reactions in which only the initially electron-deficient atom is something other than carbon, but may be applied to rearrangements in which any of the carbon atoms of formula L have been replaced with other elements. 

As a second possibility, lipid-protein interaction must be considered. The red shift might be explained in terms of hydrophobic interaction of the hydrocarbon chains of phospholipids with the protein in such a way that the amide chromophores are transferred to a less polar environment (89). Again, the hypothesis can be tested by removal of lipid. The existence of the red shift in lipid-depleted mitochondria and in lipid-free mitochondrial structural protein shows that lipid-protein interaction is not necessary to produce the ORD spectra characteristic of membranes. It is possible that if some molecular rearrangement occurs during the extraction process, a red shift caused by hydrophobic lipid-protein association could be replaced with a red shift arising from hydrophobic protein-protein association. Such an explanation is unlikely, especially in view of the retention of the unit membrane structure in electron micrographs taken of extracted vesicles (30). On the basis of ORD, then, the most reasonable conclusion is that the red shift need not be assigned to lipid-protein association. 

In a similar manner, the dihydropyrrole derivatives were investigated. The Ns protected cis- precursor 15b underwent ring rearrangement to give 23 in an 89% yield in a ratio of 15b 23 of 1 10. However, only a ratio of 2.5 1 was observed in the metathesis of the trans-precursor 16b. The Ns protection group was replaced with CBz to give 25. The subsequent RRM to yield 26 proceeded with complete conversion. 

This is called a steady-state approximation and is expressed mathematically by setting the rate of ES formation equal to the rate of ES consumption (Equations 4.6 and 4.7). After a number of rearrangements, Equation 4.7 can be solved for [ES] (Equation 4.8). The collection of three rate constants is replaced with a single term, Km, the Michaelis constant. 

An ester group at C-3 or C-5 is not different in function from any ester in aliphatic or aromatic compounds. The ester can be converted into an amide or a hydrazide, or it may be hydrolyzed. The hydrazide can be converted into an acid azide and rearranged to an isocyanate which in turn will form a carbamate or can be hydrolyzed to an amine. However, the amine group can be replaced with chlorine by diazotization in hydrochloric acid, not an ordinary pattern of behavior (76AHC(20)65) although similar reactions do occur in the 1,2,4-triazole ring system. 

Asymmetric [2,3]sigmatropic rearrangements can proceed via optically active selenoxides. It has been shown that the Davis oxidant 158 can be used for the oxidation of selenides such as 172. The reaction product, after oxidation and rearrangement, is the allylic alcohol 173 formed with 35% ee (Scheme 50).279,282 Also Sharpless conditions (Ti(/ -PrO)4, (+)-DIPT, /-BuOOH) have been applied to this reaction and the product has been obtained in 69% ee. When, however, the phenyl selenide moiety in 172 is replaced with an or/ < -nitrophenyl selenide, the selectivity is increased to 92% ee in the allylic alcohol 173 using Sharpless conditions.296 Other selenides such as 2 -pyridyl or ferrocenyl selenides gave much lower selectivities. 

As discussed for the previous two rearrangements, the carboxylate groups in 10 and 11 were replaced with hydrogen atoms and the computational problem reduces to investigating the rearrangement of the radical derived from propylamine [35] ... 

Divinylcyclopropanes in which one of the vinyl groups has been replaced with an isocyanate moiety also undergo a facile Cope rearrangement. ... 

Treatment of bicyclo[4.1.0]heptan-2-ols with perchloric acid in acetic acid caused very clean rearrangement with formation of cyclohept-3-enyl acetates (Table 1). Only in the case of cxo-7-methylbicyclo[4.1.0]heptan-2-ol was the cyclohex-2-enyl acetate the major product probably because the 7-methyl group conferred additional stabilization on the carbocation formed by j0-scission of the outer cyclopropane bond. The same type of reactant could be oxidatively rearranged using pyridinium chlorochromate to afford cyclohepten-4-ones, together with (chloromethyl)cyclohexenes. However, if the chloride in the reagent was replaced with tetrafluoroborate, or if pyridinium chlorochromate was used with silver(I) nitrate, formation of the substituted cyclohexenes was completely suppressed, e.g. formation of 7 from 6, although the reported yields were low. ... 

---