The first synthesis of natural alkaloid capparine A

Substances containing a spirooxindole framework display important biological activities. Natural alkaloid capparine A [(S)-(-)-1] has an anti-inflammatory effect. In the present study, attention has been paid to the first total synthesis of natural capparine A [(S)-(-)-1]. Racemic capparine A [(-+/-)-1] was synthesized by bromospirocyclization of 6-methoxy-1-Boc-brassinin with water, followed by oxidation of obtained spirobrassinol derivatives and removal of the Boc group. Synthesized racemic capparine A [(-+/-)-1] was enantioresolved by derivatization with (1R,2S,5R)-menthyl chloroformate, chromatographic separation of diastereoisomers and the cleavage of the chiral auxiliary using sodium methoxide. Screening of antiproliferative activity against human cancer cells revealed no anti-proliferative activity of the capparine A [(S)-(-)-1]. (C) 2020 Elsevier Ltd. All rights reserved.