Starting from cholesterol the three possible stereoisomeric 1,4‐benzodioxanes 24, 31, 32 and a series of analogues with 2βH,3βH configuration (25–27, 29, 30) have been synthesized. The α band of the 1,4‐benzodioxane chrompohore has been unequivocally identified in the CD spectra between 325–300 nm. For its Cotton effect the same helicity rule is valid as for homochirally analogous tetralins: the P/M helicity of the heteroring leads to a positive/negative CD within the α‐band. The (2′R,3′R) configuration of 6 has been established by a comparison of its CD data with those of 39 and with the help of the above‐mentioned helicity rule. This allows the assignement of the (2S,2′R,3′R) configuration of (−)‐silandrin (3).
- Circular dichroism
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry