The New Chiral Amino Alkylphenol Synthesis And Asymmetric Induction

In this paper, from starting materials of p-cresol and corresponding carboxylic acid chlorides or carboxylic acid anhydrides, five novel aminoalkylphenols were synthesized by reactions of esterification, rearrangement, methylation, amination and hydrolysis. All these five compounds were named as 2-(1-aminoethyl)-4-methylphenol, 2-(1-aminopropyl) -4-methylphenol, 2-(1-amino-2-methylpropyl)-4-methylphenol, 2-(1-aminophenyl)-4- methylphenol and 2-(1-amino benzyl)-4-methylphenol.Also in this paper, optical active dehydroabietic acid was obtained from disproportionated rosin by recrystallation of its ethanolamine salt. Using dehydroabrietic acid was as resolving reagent, 2-(1-aminoethyl)-4-methylphenol and 2-(1-amino-2-methyl- propyl)-4-methylphenol were obtained by fractional recrystallization, and their optical purity were 100% e.e. measured chiral high pressure liguid chromatography (HPLC). In addition, L-(+)-tartaric acid and D-(-)-tartaric acid were also used as resolving reagent to obtaine (+)1-(2-methoxy-5-methylphenyl)phenylethylamine and (-)1-(2-methoxy-5- methylphenyl) with the optical purity of 100% e.e. measured with chiral HPLC.Optical pure (+)-1-(2-methoxy-5-methylphenyl)phenyl ethylamine which was prepared above reacted with (2-hydroxy-5-methylphenyl)ethyl ketone or (2-hydroxy-5- methylphenyl)phenyl ketone and the corresponding compounds containing imine group were obtained. Then, such compounds were reduced by NaBH4 to give novel chiral aminoalkylphenols with 100% and 97% d.e. checked by chiral HPLC. All described above reveal a satisfied asymmetric result of reduction.Structures of all intermediates and terminal products prepared in this paper were confirmed by IR,1HNMR and element analysis.