Multiple production of α,α-disubstituted amino acid derivatives through direct chemical derivatization of natural plant extracts: An apparently difficult but successful route

Natural plant extracts are rich in chemical entities with structural, stereochemical, and functional group diversity and complexity. Here, such privileged extracts were effectively harnessed as synthetic platforms for multiple production of α,α-disubstituted amino acid derivatives through the direct chemical derivatization under the Bucherer–Bergs reaction conditions. The derivatization proceeded with chemoselectivity, enough to identify a series of novel hydantoins 5 and 10–13 and cyclic carbamates 6 and 14–16, starting with the ethyl acetate extracts of Paeonia suffruticosa and Zingiber officinale, respectively. The substrate extracts were definitely selected through the quantitative and qualitative analyses of 68 natural plant candidates.