Dicyclohexylcarbodiimide → 4,4,4-Trifluoro-3-methyl-but-2-enoic acid {2-[5-(tert-butyl-dimethyl-silanyloxy)-8a-methyl-decahydro-naphthalen-1-yl]-propyl}-amide

Participants

Reaction Steps

701 mg (2.06 mmol) of (S)-2-[(1R,4aR,5S,8aR)-5-(tert-Butyl-dimethyl-silanyloxy)-8a-methyl-decahydro-naphthalen-1-yl]-propylamine, 532 mg (1.5 eq.) of rac-3-trifluoromethyl-3-hydroxy-butyric acid, and 50 mg (0.2 eq.) of DMAP (N,N-dimethylaminopyridine) were dissolved in 20 ml of CH2Cl2. At 0° 680 mg (1.6 eq.) of DCC (dicyclohexylcarbodiimide) was added and the mixture allowed to react for 4 h at ambient temperature. The precipitated urea was filtered off and the filtrate evaporated to dryness. Flash chromatography (SiO2, hexane/AcOEt=85/15) yielded in the less polar fractions 149 mg of unwanted 4,4,4-trifluoro-3-methyl-but-2-enoic acid {2-[5-(tert-butyl-dimethyl-silanyloxy)-8a-methyl-decahydro-naphthalen-1-yl]-propyl}-amide and in the more polar ones 811 mg of the title compound as colorless oil. Medium pressure chromatography of the latter (SiO2, hexane/AcOEt=90/10) gave in the less polar fractions 367 mg of the (R)-butyramide and in the more polar ones 314 mg of the (S)-isomer, both as white foam. For determination of abs. configuration see d] below.

Provenance & Evidence