Scheme 3. Synthesis of oCOm-19 reagents and conditions: (a) BocNHCH₂CH₂NH₂, CH₂Cl₂, 0 °C to rt (69%). (b) Br₂, CCl₄, reflux. (c) NEt_3, THF, 0 °C (57% over two steps). (d) PhCH₃, 15, reflux, (93%). (e) DBU, THF, rt, (88%). (f) 6 M HCl, 1,4-dioxane, 0 °C to rt, A^– = Cl^– (99%), A^– = TFA^–, (34% + inseparable mixture of oCOM-19 and BP-CO-19). (g) 6 M HCl, 1,4-dioxane, 0 °C to rt, (95%).