allow RCM macrocyclization with maintenance of the critical
‘P3T4A5P6’ recognition region. By employing a range of chain
lengths in the N-alkenyl side chains, a series of macrocycles (1–
4) could be constructed that would vary in ring size and location
of ring-closure attachments (Fig. 1). In this fashion, we could explore
a variety of macrocycle structures in an attempt to arrive
at optimum configurations. A similar generation of libraries of
macrocyclic peptides has previously been described as an approach
at interrogating bioactive conformations.