Fuss, Werner published the artcile< Previtamin D: Z-E photoisomerization via a Hula-twist conical intersection>, Category: alcohols-buliding-blocks, the main research area is previtamin photoisomerization conical intersection rotamer CD.
On photoisomerization of previtamin D – a steroid Z-triene – produced in situ by ring opening of 7-dehydrocholesterol in a cold matrix, it was found in A.M.Muller et al. [Angew.Chem., Int.Ed., 1998, 37, 505-507] that the product (tachysterol) had rotated not only its central double bond but also an adjacent single bond. This is called a Hula twist (HT) due to the alternative description, in which it is just one central CH group that rotates. It was pointed out that the results directly support the calculated mol. structure at a conical intersection, which mediates the Z-E isomerization of polyenes. With a more sophisticated technique, Saltiel et al. (J.Phys.Chem.Lett., 2013, 4, 716-721) confirmed this tachysterol rotamer as the main product but found two addnl. conformers. They believed to have seen also three previtamin D conformers, suggested to be a result of hot-ground-state reactions from the primary rotamer, and interpreted all tachysterol products to be a result of a double-bond twist (DBT), not a HT. On the basis of published CD data and consideration of other reactions, it is here shown that under these conditions hot-ground-state reactions are unimportant or even negligible and that there is practically only a single conformer of previtamin D after ring opening. All products can be easily understood on the basis of an HT-type conical intersection, which is thus further supported. Invoking a published pretwist model even rationalizes product ratios. The two twists in HT are concerted. Furthermore HT is fully consistent with the NEER principle (nonequilibration of excited rotamers) and even offers addnl. possibilities for conformer control.
Physical Chemistry Chemical Physics published new progress about Bond angle, torsional. 434-16-2 belongs to class alcohols-buliding-blocks, and the molecular formula is C27H44O, Category: alcohols-buliding-blocks.
Referemce:
Alcohol – Wikipedia,
Alcohols – Chemistry LibreTexts