Oxidation of 3β-Acetoxy-21β-acetyl-20β,28-epoxy-18α,19βH-ursane into Novel gem-Chloronitro- and 1,2,4,5-tetraoxane derivatives
2018 ◽
Vol 13
(3)
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pp. 1934578X1801300
Keyword(s):
X Ray
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The first oxidative transformations of 3β-acetoxy-21β-acetyl-20β,28-epoxy-18α,19β H-ursane at the 21β-acetyl reaction center were performed. Ursane-type 1,2,4,5-tetraoxanes were synthesized by acid-catalyzed peroxy-condensation with cyclohexanone bis-hydroperoxide, and oxidation of the C(28)H2 group to C(28)=O was also observed. The ursane-bearing exogenous oximino-moiety was formed as a mixture of syn- and anti-isomers (1:1). Oxidative chlorination of oxime via NaCl/oxone led to the diastereomeric mixture of novel ( R) and ( S)- gem-chloronitro-derivatives (1:1). The stereochemistry of oximino- and gem-chloronitro- derivatives was established through X-ray analysis and NMR spectroscopy.
1997 ◽
Vol 62
(5)
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pp. 746-751
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