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General procedure: General Procedure A for Rink Amide Resin Activation. Rink amide resin (Advanced ChemTech) was mixed with DCM (1 mL per 100 mg resin) and then shaken for 30 minutes. After activation, resin was washed three times with DMF (1 mL per 100 mg resin). [0079] General Procedure B for the Removal of the Fmoc Group from the Rink Amide Resin. Rink amide resin was mixed with 20% piperidine in DMF (1 mL per 100 mg resin) and shaken for 30 minutes, and then washed with DMF (1 mL per 100 mg resin, 3 times), isopropanol (1 mL per 100 mg resin, 3 times), and DCM (1 mL per 100 mg resin, 3 times) sequentially. The removal of the Fmoc group was confirmed by the ninhydrin test. [0080] General Procedure C for the Removal the Alloc Group from the Rink Amide Resin. The resin (200 mg) was washed with DCM (2 mL, 5 times) and shaken under 2 overnight with a solution of tetrakis(triphenylphosphine)palladium(0) (10 mg), AcOH (0.5 mL), and NMM (0.2 mL) in DCM (10 mL). The resin was then washed with DMF (2 mL, 3 times), isopropanol (2 mL, 3 times), and DCM (2 mL, 3 times). The removal of the Alloc group was confirmed by the ninhydrin test. [0081 ] General Procedure D for the Removal the Mtt Group from the Rink Amide Resin. The resin was washed with DCM (1 mL per 100 mg resin, 10 times). The resin was shaken with TFA (1% in DCM, 1 mL per 100 mg resin) for 1 minute (repeat 10 times). The resin was then washed with DCM (1 mL per 100 mg resin, 3 times), DMF (1 mL per 100 mg resin, 3 times), isopropanol (1 mL per 100 mg resin, 3 times), and DCM (1 mL per 100 mg resin, 3 times). The removal of the Mtt group was confirmed by the ninhydrin test. [0082] General Procedure E for the Coupling of Carboxylic Acids to the Rink Amide Resin. Carboxylic acids (5 equiv, 0.5 M in DMF) were first mixed with HBTU (5 equiv, 0.5 M in DMF), HOBt (5 equiv, 0.5 M in DMF), and NMM (15 equiv, 1.5 M inDMF). The mixed solution was then added to the resin and shaken for 2 hours. The resin was then washed with DMF (1 mL per 100 mg resin, 3 times), isopropanol (1 mL per 100 mg resin, 3 times), and DCM (1 mL per 100 mg resin, 3 times). The completion of the coupling reaction was confirmed by the ninhydrin test. [0083] General Procedure F for Peptide Cleavage from the Rink Amide Resin. The resin was washed with DCM (1 mL per 100 mg resin, 5 times) and subsequently shaken with a solution of 95% TFA, 2.5% TIS, and 2.5% H20 (1 mL per 100 mg resin) for 2 hours. The resin was removed by filtration, and the TFA was evaporated under vacuum. The crude peptide was obtained after trituration with diethyl ether (5 mL per 100 mg resin, 2 times). Compound 6a was synthesized using standard Fmoc chemistry on the Rink amide resin in a disposable syringe with a frit (Figure 16). Rink amide resin (200 mg, 0.7 mmol/g loading, 0.14 mmol) was first activated with DCM (2 mL, general procedure A). Fmoc group was removed by piperidine (20% solution in DMF, 2mL, general procedure B). The resin was the coupled with Fmoc-Lys(Mtt)-OH (general procedure E). After the deprotection of Fmoc group (general procedure B), the resin was couple with Fmoc^-Ala-OH (general procedure E). The resin was treated with piperidine (general procedure B) and coupled with Fmoc-Dpr(Boc)-OH (general procedure E). The resin was treated with piperidine (general procedure B) and coupled with Fmoc- Orn(Alloc)-OH (general procedure E). The Fmoc group was removed (general procedure B), and the resin was coupled with Fmoc-F2Pmp-OH (general procedure E). The resin was treated with piperidine (general procedure B) and coupled with BMBA (general procedure E). The Alloc group was removed (general procedure C), and resin was coupled with mlBA (general procedure E). The resin was treated with 1% TFA in DCM for the removal of Mtt group (general procedure D) and coupled with 5-FAM (general procedure E). Compound 6a was cleaved from beads (general procedure F). Crude peptide was purified by HPLC to afford Compound 6a (8.6 mg, 4% yield). MS (ESI): calculated for [M] 1477, found [M+H]+ 1478. Figure 16 depicts the synthesis of Compound 6a: (a) 30% piperidine/DMF; (b) Fmoc-Lys(Mtt)-OH/HBTU/HOBt/NMM; (c) Fmoc-p-Ala- OH/HBTU/HOBt/NMM; (d) Fmoc-Dpr(Boc)-OH/HBTU/HOBt/NMM; (e) Fmoc- Orn(Alloc)-OH/HBTU/HOBt/NMM; (f) Fmoc-F2Pmp-OH/HBTU/HOBt/NMM; (g) 3- bromo-4-methylbenzoic acid/HBTU/HOBt/NMM; (h) Pd(0)/NMM/AcOH; (i) 3- iodobenzoic acid/HBTU/HOBt/NMM; (j)l% TFA/TIS/DCM; (k) 5-Carboxyfluorescein/ HBTU/HOBt/NMM; (1) 95% TFA/H2O/TIS. |
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