• ECD calculations confirm configuration of as (R,R)
• Reassign to (R,R) as well,
• Establishing the as retention.
• Ottenheijm's epithiodioxopiperazine:
  1. "(S,S)" [α]_D -53°_obs
  2. (R,R) [α]₅₈₉ -131°_calc, corresponding to ~70% (R,R) and ~30% (S,S)

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