We first began our structural investigation with peptides 7a and 8a (Figure ). Both solution structures possessed key similarities and differences. Most notably, the characteristic endocyclic amine IMHB between the NH of Gly2 and the nitrogen of Pro1 was retained in both compounds. Likewise, both structures fostered b-turns between the NH of Gly5 and the carbonyl of Gly2. The noticeable difference between the two structures was a g-turn found in peptide 8a in place of a bturn at the anilide NH in 7a. To examine the structural effects of altering the heterobiaryl f-angle as well as the substitution pattern of the heterobiaryl linage further, we turned our attention toward peptide 11a-b and 12a-b. As previously illustrated, this group of peptides were made using both reagents Pinc and 2. Indeed, a high degree of structural modulation was obtained in this group of peptides (Figure ). The anilide NH of 11a and 11b both were involved in formation of well-defined b-turns. However, slight variations were measured in both the f and y dihedral angles of the i+1 and i+2 residues. In peptide 12a, substitution of a methyl group on the aryl ring resulted in complete disruption of any turn motif at the anilide NH. In contrast, methylated oxazole-containing 12b was found to contain a tight g-turn in place of the b-turn observed in 11a and 12b. This trend indicated that a bulky-methyl substituent pointing into core of the macrocycle leads to disruption of b-turnlike transannular IMHB and fosters the formation of tighter/shorter turns. Much like with the peptides of Figure , peptide 11a, 11b, 12a and 11b all possessed the classical endocyclic amine IMHB between the NH of Gly2 and the reduced amide of Pro1.