4079-64-5Relevant articles and documents
Enantiomerically Pure Dibenzyl Esters of l -Aspartic and l -Glutamic Acid
Bolchi, Cristiano,Valoti, Ermanno,Fumagalli, Laura,Straniero, Valentina,Ruggeri, Paola,Pallavicini, Marco
, p. 878 - 883 (2015/07/27)
(S)-Dibenzyl aspartate p-toluenesulfonate [(S)-1·TsOH] and (S)-dibenzyl glutamate p-toluenesulfonate [(S)-2·TsOH] were efficiently prepared from the respective l-amino acids and benzyl alcohol with very high yields by using cyclohexane as a water azeotroping solvent instead of benzene, carbon tetrachloride, toluene, or benzyl alcohol itself, as reported in literature methods. Preventively, chiral HPLC methods were developed to determine the enantiomeric excess of the two diesters and DSC analyses were performed on the respective p-toluenesulfonates. With the aid of such investigation tools, we demonstrated that (S)-1·TsOH and (S)-2·TsOH were formed enatiomerically pure in cyclohexane, whereas more or less pronounced racemization occurred both in toluene and in benzyl alcohol. The two one-pot procedures, which did not require crystallization of the product or any other purification step, were accomplished on multigram scale.
