Gold(I)-catalyzed tandem 1,3-acyloxy migration/ferrier rearrangement and its application
Date of Issue2017
School of Physical and Mathematical Sciences
During our investigation to study the transition metal mediated C-glycosylation, a gold(I)-catalyzed tandem 1,3-acyloxy migration/Ferrier rearrangement has been serendipitously discovered and we have went on to establish a new concise way to furnish vinyl-C-glycoside product and 8-oxabicyclo[3.2.1]octane derivatives in good yields and exclusive diastereoselectivity. The intermolecular gold(I)-catalyzed tandem 1,3-acyloxy migration/Ferrier rearrangement with glycals and propargylic esters allowed access to the a, (E)-selective C-vinyl glycoside products in the presence of PPh3AuOTf. Both D-glucal and D-glactal could be applied into the C-vinyl glycosylation through this methodology. The intramolecular gold(I)-catalyzed tandem 1,3-acyloxy migration/Ferrier rearrangement with glycal-linked propargyl esters allowed access to the optically pure 8-oxabicyclo[3.2.1]octane derivatives in the presence of PPh3AuSbF6. The reaction mechanism was further investigated with a series of experiments. In addition, the 8-oxabicyclo[3.2.1]octane products was evaluated for their cytostatic activities against selected human cancer cells lines and most compounds have shown promising inhibitory effects with the IC50.value as low as 2.31 µM, which suggested that these oxabicyclo[3.2.1]octane derivatives could be potential anti-tumor reagents. Furthermore, it was found that the 8-oxabicyclo[3.2.1]octanes with divinyl ketone motif could undergo asymmetric interrupted Nazarov cyclization to generate the optically pure 11-oxatricyclo[188.8.131.52]undecanes catalyzed by BF3•OEt2, suggesting the possibility of applying the methodology in total synthesis of complex natural product.