Neighboring-group participation in reactions

II. The Nature and Activating Effect of Neighboring-group Participation in Reactions at the Lactol Carbon Atom. 

According to these previous results, a generalization was proposed67 for an effective gas-phase neighboring group participation in reactions of organic molecules as follows ... 

Also at this time examples of neighboring group participation in addition reactions were known, and work was commencing on neighboring group participation in reactions of derivatives of carboxylic acids and of phosphate esters. ... 

Examples of neighboring group participation in isoxazole bromination have been reported. When the isoxazolylpropanol (80) was treated with bromine in pyridine, it gave the spiro (furan-2,5-isoxazole) (81) (74BAU2566). The corresponding propenoic acid gave 82 [76JCS(P1)1694], whereas a similar process accounts for the reaction of... 

In organic chemistry it is well known that a substituent directly linked to a reaction center has a profound effect on the latter s reactivity. The influence of a remote substituent has also received much attention as more organic molecules are being scrutinized. Thus, neighboring group participations in solvolysis are generally observed. Certainly, the full attribution of a substituent must be the sum of electronic, steric, and stereoelectronic factors. 

The absence of neighboring-group participation in deamination reactions seems to be a fairly general phenomenon in the chemistry of these hot ions, although when the neighboring group is as reactive as p-methoxyphenyl some participation may occur.41... 

The above definition excludes a number of types of heteroatom cyclofunctionalization reactions from discussion in this chapter. Examples include neighboring group participation in which the cyclic structure is only a transient intermediate cyclization reactions where the C—C tr-bond is internally activated... 

Morzycki, J.W., Gryszkiewicz, A., and Jastrzebska. I., Neighboring group participation in epoxide ring cleavage in reactions of some 16a,17a-oxidosteroids with lithium hydroperoxide. Tetrahedron, 57, 2185, 2001. 

In contrast to sulfides, sulfoxides and sulfones show no tendency of neighboring group participation in exchange reactions at the 0-carbon atom, see S) 5 experiments... 

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