反应详情

The compound of formula XV is then treated with benzylchloroformate in a polar solvent such as water, water/acetone, chloroform, dichloroethane or ethyl acetate, in the presence of a base such as triethylamine or sodium bicarbonate, to yield the N-carbobenzyloxy piperidine (N-Cbz piperidine) of formula XVI having the same stereochemistry (i.e., wherein R2 and --COOCH3 are in the cis configuration). This reaction may be carried out at temperatures from about 0° C. to about 100° C., preferably about 25° C., for about 5 minutes to 18 hours. Treatment of the compound of formula XVI so formed with about 5 equivalents each of trimethyl aluminum and ammonium chloride in a nonpolar solvent such as benzene or toluene for about 0.5 to about 16 hours yields a compound of the formula XVII having the same stereochemistry. Reaction temperatures may range from about room temperature to about 100° C., with about 50° C. being preferred.