[C:1]([NH:8][C@@H:9]([C:18](O)=[O:19])[CH2:10][C:11]1[CH:16]=[CH:15][CH:14]=[C:13]([I:17])[CH:12]=1)([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2].CN1CCOCC1.ClC(OCC(C)C)=O.[BH4-].[Na+]>C1COCC1.CC(N(C)C)=O>[C:4]([O:3][C:1](=[O:2])[NH:8][C@@H:9]([CH2:18][OH:19])[CH2:10][C:11]1[CH:16]=[CH:15][CH:14]=[C:13]([I:17])[CH:12]=1)([CH3:5])([CH3:7])[CH3:6]A solution of Boc-3-iodo-D-phenylalanine (6.32 g, 16.2 mmol) and 4-methyl-morpholine (1.87 ml, 17 mol) in THF (13 mL) was added dropwise to a −15° C. solution of isobutyl chloroformate (2.22 mL, 17 mmol) in THF (13 mL) and the resulting suspension was stirred for 1 h. The cold reaction mixture was filtered and the filter cake was rinsed with THF. The filtrate was added dropwise to a 0° C. solution of NaBH4 (0.92 g, 24.2 mmol) in dimethylacetamide (7 mL) and the resulting suspension was warmed to RT and stirred for 1 h. The reaction mixture was cooled back to 0° C. and quenched with 1M aq. citric acid. Additional water was added and the mixture was concentrated in vacuo. The remaining aqueous phase was acidified with 1M aq. HCl before being filtered. The filter cake was rinsed with water and dried under HV to give the title compound as an orange solid that was used further without purification. LC-MS A: tR=0.84 min; [M-Me]+=362.93.
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