Resolution of (S,S)‐4‐(2,2,4‐tri­methyl­chroman‐4‐yl)­phenyl camphanate and its 4‐chromanyl epimer by crystallization

Dianin's compound (4‐p‐hydroxy­phenyl‐2,2,4‐tri­methyl­chroman) has been resolved by crystallization of the (S)‐(−)‐camphanic esters (S,S)‐ and (R,S)‐4‐(2,2,4‐tri­methyl­chroman‐4‐yl)­phenyl 4,7,7‐tri­methyl‐3‐oxo‐2‐oxabi­cyclo2.2.1]heptane‐1‐carboxyl­ate, both C₂₈H₃₂O₅, from 2‐methoxy­ethanol, yielding the pure S,S diastereomer. The relative stereochemistry of both diastereomers has been determined by X‐ray crystallography, from which the absolute stereochemistry could be deduced from the known configuration of the camphanate moiety. The crystallographic conformations have been analysed, including the 1:1 disorder of the R,S diastereomer.