state of ring formation and the absence of significant strain associated with formation of rings of these sizes. For the formation of different ring sizes via cyclization of substrates of varying tether length, the order of reaction rates (rate constants k_n for the formation of an n-membered ring) is usually k₅ > k₆ > k₃ > k₇ > k₄ as shown below for a series of ?-bromoalkylamines. This somewhat complicated rate trend reflects the interplay of these entropic and strain factors:

For