Study of the Reaction of Unprotected Amino Acids in Aqueous Media and its Application for the Short-Step Synthesis of Ergot Alkaloids

点击翻译按钮获取中文摘要

1)Several free amino acids, phrnylglycine, phenylalanine, tryptophan were heated at 100-130℃ under alkaline or acidic condition in water or various polar organic solvents.Although serious racemization and decomposition occurred in polar organic solvents such as DMF, DMSO, or ethylene glycol under alkaline condition (K_2CO_3, KOH, Et_3N), those phenomenon did not occur, or were largely decreased in water or water containing organic solvent under the same alkaline condition.2)Bromination of unprotected phenylalanine with bromoisocyanuric acid sodium salt in strong acidic solution (60% H_2SO_4) gave the mixture of 2-bromo-and 4-bromophenylalanine in 31% and 58% yield, respectively.3)The reaction of benz[e]-, benz[f]-, benz[g] indoles with dl-serine in the presence of Ac_2O in AcOH at 50-60℃ gave the corresponding dl-N-acetylbenztryptophanes in 42-59% yield accompanied with 2,3-di-subusituted derivatives as by-products. Kinetic resolution of the above dl-N-acetylbenztryptophans by Aspergillus acylase gave corresponding optically pure(S)-benztryptophans.