Ethyl trifluoromethanesulphonate → HCID 86747926, compound

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 8.65 ml (5.2 mmol) KHMDS (0.6M solution in toluene) in 50 ml dry THF was added 1.96 g (4.0 mmol) of dimethyl N-benzyl-N-(9-phenylfluorenyl)-aspartate of Example 3 dissolved in 8 ml THF drop by drop at -74° C. under N2. The pale yellow solution was stirred at -74° C. for 45 minutes then 568 μl (4.4 mmol) EtOTf were added neat at once at -76° C. After 10 minutes the reaction was quenched with 3 ml MeOH and partitioned between 40 ml 1M H3PO4 and 50 ml Et2O. The water layer was extracted with 40 ml Et2O and the combined organic layers were dried (MgSO4) and evaporated. The residue was purified by flash-chromatography (Kieselgel, Hexane/EtAc 8:1) to yield a mixture of dimethyl 3-ethyl N-benzyl-N-(9-phenylfluorenyl)-aspartate (20:1 mixture of diastereomers). The diastereomers were separated by MPLC (Kieselgel, Hexane/EtOAc 15:1) to yield the desired compound.

Provenance & Evidence