I made an attempt to synthesize an unnatural amino acid containing phenyl group. In the last step of the synthesis I deprotected trityl protected amino group using 1N HCl aq., extracted, collected aq. layer, neutralized it with NaHCO3 aq. till pH roughly 8, evaporated water and used it further in deprotection of methyl ester group using LiOH monohydrate, quenched reaction with water, neutralized the media and purified the residue by reverse column. After purification i can see a strange impurity in the downfield region of the NMR, it looks like a second set of peaks resembling the product (amino acid) peaks but in the upfield region, i did not observe any extra methine and benzylic proton peaks. The amino acid synthesis started from pure enantiomeric starting material. So, I am not sure what could happen during the deprotection step. I would appreciate your help or any suggestions. Thank you. I will attach a proton NMR of the aromatic region where impurity is observed.