Dicyclohexylcarbodiimide → N,N'-Dicyclohexylurea

Beteiligte Stoffe

Reaktionsschritte

t-Boc-Ala (4.16 gr, 22 mmol) was dissolved in 11 ml dioxane. N,N′-Dicyclohexylcarbodiimide (DCC) (11 mmol in 11 ml 1 M DMF) was then added and the reaction was carried out for 3 hours at 25° C. under stirring. Dicyclohexylurea (DCU) formed was removed by centrifugation. The symmetrical anhydride product thus obtained (t-Boc-Ala-anhydride) was reacted overnight under stirring with 2-aminofluorene (0.925 g, 11 mmol) in 30 ml dioxane-water (1:1, v:v) containing 11 mmol of NaHCO3. The white solid formed was collected and dried under P2O5 in vacuum for 24 hours. Intermediate a was obtained in 60% yield (1.31 g, 3.34 mmol). It migrated on TLC (dichloromethane) with Rt=0.17. Mass-spectroscopy revealed a mass of 352.45 Da (calculated mass=352.2 Da).

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