( R )‐4‐(4‐Aminophenyl)‐2,2,4‐trimethylchroman and ( S )‐4‐(4‐aminophenyl)‐2,2,4‐trimethylthiachroman

The title compounds, C 18 H 21 NO and C 18 H 21 NS, in their enantiomerically pure forms are isostructural with the enantiomerically pure 4‐(4‐hydroxyphenyl)‐2,2,4‐trimethylchroman and 4‐(2,4‐dihydroxyphenyl)‐2,2,4‐trimethylchroman analogues and form extended linear chains via N—H...O or N—H...S hydrogen bonding along the [100] direction. The absolute configuration for both compounds was determined by anomalous dispersion methods with reference to both the Flack parameter and, for the light‐atom compound, Bayesian statistics on Bijvoet differences.