Stereochemistry of 16a-Hydroxyfriedelin and 3-Oxo-16-methylfriedel-16-ene Established by 2D NMR Spectroscopy

Stereochemistry of 16a-hydroxyfriedelin and 3-Oxo-16-methylfriedel-16-ene established by 2D NMR spectroscopy.

Friedelin (1), 3beta-friedelinol (2), 28-hydroxyfriedelin (3), 16alpha-hydroxyfriedelin (4), 30-hydroxyfriedelin (5) and 16alpha,28-dihydroxyfriedelin (6) were isolated through fractionation of the hexane extract obtained from branches of Salacia elliptica. After a week in CDCl(3) solution, 16alpha-hydroxyfriedelin (4) reacted turning into 3-oxo-16-methylfriedel-16-ene (7). This is the first re...

Chapter 16 X-ray Spectroscopy

Before the discovery of the diffraction of X-rays in crystals some very important studies had been made of the quality of these rays by measuring their absorption in different materials. Especially Barkla had been able, by this rather simple method, to find some fundamental properties of the X-rays when they were scattered by different elements. It was known that the radiation leaving an X-ray ...

cover Vol.16,no.3- June 2019

16-Isopropyl-5,9-dimethyl­tetra­cyclo­[10.2.2.01,10.04,9]hexa­dec-15-ene-5,14-dimethanol

The title compound, C(23)H(38)O(2), a tetra-cyclo-[10.2.2.0(1,10).0(4,9)] hexa-decane structure, crystallized with four independent mol-ecules in the asymmetric unit. In the crystal, these independent mol-ecules are linked by O-H⋯O hydrogen bonds, forming a polymeric chain propagating in [100].

Rsc_cp_c3cp54834a 3..16

The quasi two-dimensional electron gas on a metal film can transmit to the surface even minute mechanical disturbances occurring in the depth, thus allowing the gentlest of all surface probes, helium atoms, to perceive the vibrations of the deepest atoms via the induced surface-charge density oscillations. A density functional perturbation theory (DFPT) and a helium atom scattering study of the...