With methyl ester of N-acylated L-3-（3,4-dihydroxyphenyl）alanine（L-DOPA） as starting material, racemic derivatives of 3-hydroxymethyl-1,2,3,4-tetrahydroisoquinoline were obtained with cyclization by Bischler-Napie...With methyl ester of N-acylated L-3-（3,4-dihydroxyphenyl）alanine（L-DOPA） as starting material, racemic derivatives of 3-hydroxymethyl-1,2,3,4-tetrahydroisoquinoline were obtained with cyclization by Bischler-Napie- ralski（BN） reaction followed by reduction of methyl ester group to hydroxymethyl, while the optical pure enantiomers were prepared by the reduction of the methyl ester group to hydroxymethyl prior to cyclization with BN reaction. Racemerization took place in the BN stage in the presence of methyl ester, an electron-withdrawing group adjacent to chiral center. Therefore, the sequence of synthetic stages of cyclization and reduction, and subsequently whether there is electron-withdrawing group or not determines the chiral optical activity of the products.展开更多
文摘With methyl ester of N-acylated L-3-（3,4-dihydroxyphenyl）alanine（L-DOPA） as starting material, racemic derivatives of 3-hydroxymethyl-1,2,3,4-tetrahydroisoquinoline were obtained with cyclization by Bischler-Napie- ralski（BN） reaction followed by reduction of methyl ester group to hydroxymethyl, while the optical pure enantiomers were prepared by the reduction of the methyl ester group to hydroxymethyl prior to cyclization with BN reaction. Racemerization took place in the BN stage in the presence of methyl ester, an electron-withdrawing group adjacent to chiral center. Therefore, the sequence of synthetic stages of cyclization and reduction, and subsequently whether there is electron-withdrawing group or not determines the chiral optical activity of the products.
