Biosynthesis of sitosterol in higher plants involves the double bond isomerization of isofucosterol to 24-ethyldesmosterol followed by reduction of the latter. The mechanism of the double bond isomerization from Δ24(28) to Δ24(25) was investigated by feeding [28-13C,28-2H] doubly labeled isofucosterol to cell cultures of Oryza sativa and 2H-decoupled 13C, 1H shift correlation NMR analysis of the biosynthesized
Pd-Catalyzed Cascade Reactions of Aziridines: One-Step Access to Complex Tetracyclic Amines
作者:Jonathan P. Knowles、Hannah G. Steeds、Maria Schwarz、Francesca Latter、Kevin I. Booker-Milburn
DOI:10.1021/acs.orglett.1c01403
日期:2021.7.2
cycloaddition is shown to transform tricyclicaziridines into complex, stereodefined tetracyclic products in a single step. This highly unusual cascade process involves a diverted Tsuji–Trost sequence leading to a surprisingly facile intramolecular Diels–Alder reaction. The starting materials are accessible on multigram scales from the photochemical rearrangement of simple pyrroles. The tetracyclic amine products