A spiroketal bisphosphine (SKP) derived chiral digold complex is identified as a powerful catalyst for the highly diastereo- and enantioselective synthesis of spirocyclopropyloxindoles from diazooxindoles and a broad range of alkenes, including both cis and trans 1,2-disubstituted alkenes.
We report a highly enantioselective Cu(I)-catalyzed azide-alkyne cycloaddition via asymmetric desymmetrization of oxindole-based 1,6-heptadiynes, which furnishes quaternary oxindoles bearing a 1,2,3-triazole-containing moiety with 84-98% ee.
Huperzine Q (1) and N-oxyhuperzine Q (2), two novel irregular fawcettimine-type Lycopodium alkaloids were isolated from the CHCl 3 fraction of the basic material of the whole plant of the Chinese medicinal herb Huperzia serrata. Their structures were determined as 13-epi-13b,16-epoxydihydrofawcettimine (1) and N-oxy-13-epi-13b,16-epoxydihydrofawcettimine (2) by means of spectroscopic studies and X-ray crystallographic analysis.Introduction. ± Huperzia serrata (Thunb.) Trev. (Huperziaceae) is one of the most commonly used traditional Chinese herbal medicines for the treatment of contusion, strain, swelling, and schirophrema [1]. The discovery that huperzine A, a Lycopodium alkaloid isolated from this plant, was a potent acetylcholinesterase inhibitor [2] has prompted us reinvestigate the chemical constituents of this plant. As a continuation of our work [3], we re-examined the CHCl 3 extract of the basic materials of dry whole plants (10 kg), and obtained huperzine Q (1) and N-oxyhuperzine Q (2), two novel compounds that represent a unique structural type among the Lycopodium alkaloids [4]. In the present paper, we report the isolation and structural elucidation of the above compounds.
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