12,132513-32-7; 13,37466-41-4; 14,138571-38-7; 15,138571-39-8; 16, 138605-23-9; 17, 138571-40-1; 18, 138571-41-2; Cbz-m(3- Ac)-OMe, 79677-60-4; Boc-NMe-Phe(I), 138571-42-3; BOC-D- Ala-Ala-NMe-Tyr(Me)-Ala, 112196-84-6. Supplementary Material Available: Full physical and spectroscopic characterization of 14, 16, 9, and 10 and tables comparing the spectroscopic properties ('H and "C) of 1 and 9 (6 pages). Ordering infomation is ...