Relationships between Ring Size and Rate of Cyclization

Relationships between Ring Size and Rate of Cyclization 

Many examples of intramolecular reactions leading to ring closure have served to establish a correlation between the rate of a reaction and tiie size of the ring being formed.  

SECTION 3.9. RELATIONSHIPS BETWEEN RING SIZE AND RATE OF CYCLIZATION 

A systematic effort to correlate ease of ring closure with the stereoelectronic requirements of the transition state has been developed by Baldwin and co-workers. They classify ring closures with respect to three factors (a) ring size, (b) the hybridization of the carbon at the reaction site, and (c) the relationship (endocyclic or exocyclic) of the reacting bond to the forming ring. Certain types of ring closures are found to be favorable whereas others are unfavorable for stereoelectronic reasons. The relationships are summarized in Table 3.12. 

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