Cyclative release of peptidic compounds

A method for preparing a cyclized peptidic compound of Formula

• the method comprising
• forming a cyclization reaction mixture comprising a thiophilic catalyst, a non-nucleophilic base, and a compound of Formula II:
• under conditions suitable to form the cyclized peptidic compound of Formula I, wherein
• is a solid-phase support;
• R1a is selected from the group consisting of H, NH2, C1-8 alkyl, and C3-8 cycloalkyl;
• L1 is selected from the group consisting of a bond, N—H, and —O—,
• provided that when R1a is NH2, then L1 is a bond;
• and
• provided that when L1 is —O—, then R1a is H, C1-8 alkyl, or C3-8 cycloalkyl;
• R1 is selected from the group consisting of H, NH2, C1-8 alkyl, and C3-8 cycloalkyl,
• provided than when R1 is NH2, then L1 is a bond;
• R2 is H;
• L2 is selected from the group consisting of C2-8 alkylene, C3-8 cycloalkylene, 3- to 8-membered heterocycloalkylene, C6-10 arylene, and 5- to 10-membered heteroarylene, each of which is optionally substituted with from 1 to 4 substituents selected from the group consisting of C1-4 alkyl, cyano, —C(O)Ra, —C(O)ORa, —SRa, —C1-4alkyl-SRa, and oxo, wherein the heterocycoalkylene and heteroarylene each have from 1 to 3 heteroatom ring members each independently selected from the group consisting of N, O and S;
• and
• Ra is selected from the group consisting of H and C1-8 alkyl.