Imidazole → (S)-8-Benzyloxy-4-[dimethyl-(1,1,2-trimethyl-propyl)-silanyloxymethyl]-3,4-dihydro-2H-pyrazino[1,2-a]indol-1-one

Participants

Reaction Steps

The title compound was synthesized in analogy to example 8, intermediate a), from 5-benzyloxy-1-{(S)-1-(tert-butoxycarbonylamino-methyl)-2-[dimethyl-(1,1,2-trimethyl-propyl)-silanyloxy]-ethyl}-1H-indole-2-carboxylic acid ethyl ester to give a mixture of the desired compound and the unprotected hydroxymethyl compound. The mixture was dissolved in N,N-dimethylformamide and 1 equivalent of imidazole was added. At 0° C., 1 equivalent of dimethylthexylsilyl chloride was added and the cooling bath was removed. The reaction mixture was poured on water and was extracted twice with ethyl acetate. The combined organic layers were washed with brine, dried over magnesium sulfate, filtered and evaporated. The residue was purified by column chromatography over silica gel using n-hexane:ethyl acetate (1:2 v/v) as eluant to give the desired product as a light yellow foam (35%).

Provenance & Evidence