Boron trifluoride → HCID 57304755, compound

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Reaction Steps

This compound was synthesized by adapting, to N-isobutyryl-L-cysteine, the tritylation method described by K.-Y. Zee-Cheng and C. C. Cheng, J. Med. Chem., 1970, 13, 414-418. A suspension comprising 4.1 g (21.5 mmol) of N-isobutyryl-L-cysteine [(prepared according to H. Brückner et al., J. Chromatogr., 1989, 476, 73-82), ([α]D20=+84° (c 1, CHCl3))], 5.6 g (21.5 mmol) of triphenylmethanol and 16 ml of glacial acetic acid is stirred at ambient temperature. 4.1 ml (32.2 mmol) of BF3 etherate are added dropwise to the mixture while maintaining the temperature at 20-25° C. After stirring for 3 h, the brown solution obtained is subsequently cooled to 0° C. and then 70 ml of an aqueous sodium acetate solution and 140 ml of water are added. At the end of the additions, the reaction mixture sets solid in the form of a gel. This mixture is left overnight at 0° C. and then 150 ml of ice-cold water and 120 ml of ether are subsequently added with vigorous stirring. The ethereal phase is separated by settling and the aqueous waste liquors are washed with 4×80 ml of ether. The organic phases are combined, washed with 4×60 ml of ice-cold water, dried over sodium sulfate, filtered and evaporated to dryness under vacuum. The crude product obtained is purified by washing successively with hexane (5×50 ml) to provide 13 in the form of a gum which is homogeneous by TLC with a yield of 81%. Rf (CH2Cl2/MeOH/AcOH, 9.4/0.6/0.07): 0.53. [α]D20=+21.40 (c 1.12, CHCl3).

Provenance & Evidence