Table 1. Selected examples of linear peptide (A) cyclization leading to macrocyclic (B) and amidine-based products (C and D).

Linear peptide (A)	Sequence	Major product isolated yield
14	PGLGF	34% B45
15	PGlGF	28% B
16	PALGF	12% B
17	PGLAF	9% B a
18	PGLGf	12% C
19	PS(tBu)LGF	49% B b
20	PS(tBu)LY(tBu)F	22% B
21	PGLGK(Boc)	23% B a
22	PGlGk(Boc)	8% D a
23	PGLK(Boc)	8% D a
24	PGF	8% C

^aIsolated after telescopic synthesis.

^bCyclized with d-leucine-derived dimer.