Inductive effects compounds

The ligand effect seems to depend on the substrates. Treatment of the prostaglandin precursor 73 with Pd(Ph3P)4 produces only the 0-allylated product 74. The use of dppe effects a [1,3] rearrangement to produce the cyclopen ta-none 75(55]. Usually a five-membered ring, rather than seven-membered, is predominantly formed. The exceptionally exclusive formation of seven-membered ring compound 77 from 76 is explained by the inductive effect of an oxygen adjacent to the allyl system in the intermediate complex[56]. 

Fluorinated Acids. This class of compounds is characterized by the strength of the fluorocarbon acids, eg, CF COOH, approaching that of mineral acids. This property results from the strong inductive effect of fluorine and is markedly less when the fluorocarbon group is moved away from the carbonyl group. Generally, their reactions are similar to organic acids and they find apphcations, particularly trifluoroacetic acid [76-05-1] and its anhydride [407-25-0] as promotors in the preparation of esters and ketones and in nitration reactions. 

The alkyl and alkoxy substituents of phosphate or phosphonate esters also affect the phosphorylating abiUty of the compound through steric and inductive effects. A satisfactory correlation has been developed between the quantitative measure of these effects, Tafts s O, and anticholinesterase activity as well as toxicity (33). Thus long-chain and highly branched alkyl and alkoxy groups attached to phosphoms promote high stabiUty and low biological activity. 

The fact that the equilibrium for aminopyridine 1-oxides is displaced further in favor of the amino form than is the equilibrium for aminopyridines is in accord with the mesomerism of these compounds. The stabilization of the amino forms (e.g., 241) by structures of type 240 is more effective than the corresponding stabilization in the pyridine series since the negative charge is associated with the oxygen atom. The stabilization of the imino form (e.g., 242) by structures of type 243 is less than in the pyridine series because of the adverse inductive effect of the oxygen atom. ... 

It has been proposed that the ring-expansion reaction is initiated by attack of the base at position 2 of the quinazoline oxide, which is rendered electron deficient by the inductive effect of the (V-oxide group. In fact, 2-(Chloromethyl)quinazolines, compounds that lack this feature, react with amines to give only simple substitution products.1133... 

In the N-Bz derivatives of Gly and Gly-Gly, the planar [R3Sn(IV)] moieties are bridged by -COO groups. Because of the negative inductive effect of the Ph group, which reduces the donor ability of oxygen atoms, coordination of the amide -C = O in the latter compounds could be ruled out. 

Although the reaction mechanism of this type of reactions is not fully elucidated, it is easily anticipated that no intramolecular special stabilization effect for the carbanion generated from decarboxylation is expected, different from the case of malonic acid-type compounds. Moreover, cinnamic acid derivatives that have both the electron-donating and withdrawing substituents have been reported to undergo this reaction. This fact suggests that the enzyme itself stabilizes the transition state without the aid of mesomeric and inductive effects of the other part of the substrate molecule itself. If such unknown mechanism also works for other... 

Several trends have emerged in the extensive carbon-13 NMR spectroscopy data that have been accumulated for sulfones and sulfoxides. Based on many studies of cyclic systems—particularly five- and six-membered ring sulfur compounds—these trends were shown to generally apply equally to both the cyclic and acyclic systems . Thus (a) oxidation of a sulfide to a sulfone results in a 20-25 ppm downfield chemical shift for sp -hybridized a-carbon atoms and 4-9 ppm upfield shift for / -carbons , and (b) there is very little difference between the chemical shifts of a-carbon atoms of sulfones and sulfoxides despite the difference in the inductive effects of these two functional groups . A difference is observed, however, in the H chemical shift of related cyclic sulfoxides and sulfones . 

The applicability of these methods is restricted to polyhalogenated compounds, since the inductive effect of the halogen atoms is necessary for facilitating formation of the carbanion. 

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