Related Experiment Video
Updated: Jun 1, 2026

One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates
Published on: January 15, 2018
Redetermination and absolute configuration of 7α-hy-droxy-royleanone
Abstract:
THE TITLE COMPOUND [SYSTEMATIC NAME: 7α,12-dihy-droxy-8,12-abietadiene,11,14-dione or (4bS,8aS,10R)-3,10-dihy-droxy-2-isopropyl-4b,8,8-trimethyl-1,4,4b,5,6,7,8,8a,9,10-deca-hydro-phenanthrene-1,4-dione], C(20)H(28)O(4), is an abietane diterpen-oid, which was isolated from the roots of Premna obtusifolia (Verbenaceae). Its crystal structure has been reported previously [Chen et al. (2000 ▶). Jiegou Huaxue, 19, 122-125], but the absolute configuration could not be determined using data collected with Mo radiation. This redetermination using Cu radiation shows the the absolute configurations of the stereogenic centres at positions 4b, 8a and 10 to be S, S and R, respectively. Two intra-molecular O-H⋯O hydrogen bonds [one generating an S(5) ring and one generating an S(6) ring] and a number of short C-H⋯O contacts occur. In the crystal, mol-ecules are linked into infinite chains propagating in [100] by O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions.
Related Concept Videos
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
Stereoisomerism of Cyclic Compounds
Stereochemical Effects of Enolization
Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Prochirality

