4-Methylmorpholine → tert-butyl 5-[2-[1(RS)-[[N-[(9-fluorenyl)methoxycarbonyl]-L-leucyl]amino]propyl]-4(RS),5,5-trimethyl-1,3,2-dioxaborolan-4-yl]-3(RS)-methylvalerate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

0.5 g (1.42 mmol) of N-[(9-fluorenyl)methoxycarbonyl]-L-leucine was dissolved in 7 ml of dichloromethane. 0.6 ml (5.7 mmol) of N-methylmorpholine was added and the solution was cooled to -10° C. under a nitrogen atmosphere. 0.22 ml (1.7 mmol) of isobutyl chloroformate was added and the solution was stirred for 7 minutes at -10° C. 1 g (2.13 mmol) of tert-butyl 5-[2-(1(RS)-aminopropyl)-4(RS),5,5-trimethyl-1,3,2-dioxaborolan-4-yl]-3(RS)-methylvalerate was added and the mixture was stirred at room temperature for 16 hours, then diluted with dichloromethane and extracted with 2M hydrochloric acid. The organic phase was extracted with 2M hydrochloric acid and saturated sodium hydrogen carbonate solution and then dried over anhydrous magnesium sulphate. After evaporation the residue was purified by chromatography on silica gel using ethyl acetate/hexane (1:2) for the elution. There was obtained 0.56 g of tert-butyl 5-[2-[1(RS)-[[N-[(9-fluorenyl)methoxycarbonyl]-L-leucyl]amino]propyl]-4(RS) ,5,5-trimethyl-1,3,2-dioxaborolan-4-yl]-3(RS)-methylvalerate as an oil; MS: m/e 677 [M+H]+.

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