Squaric acid esters were treated with triethyloxonium tetrafluoroborate at room temperature to produce ethoxycarbenium ion species, and subsequent addition of trimethylsilyl cyanide (TMSCN) to this intermediate at 0°C afforded O-ethyl cyanohydrins in fair to good yields. In a similar manner, the ester reacted effectively with silyl enol ether and silyl ketene acetal to give the corresponding O-ethylated addition products. On the other hand the reaction with allylsilanes preferred the formation of 1:2 adducts.
The synthesis of azabicycloalkenones bearing a vinylogous amide moiety was achieved by means of the rhodium-catalyzed decarbonylative cycloaddition of cyclobutenediones with a pendant alkene. The starting cyclobutenediones were efficiently prepared from appropriate squaricacid monoesters and N-benzylalkenylamines under microwave heating conditions.
Triggering apoptosis in cancer cells with an analogue of cribrostatin 6 that elevates intracellular ROS
作者:D. J. Asby、M. G. Radigois、D. C. Wilson、F. Cuda、C. L. L. Chai、A. Chen、A. S. Bienemann、M. E. Light、D. C. Harrowven、A. Tavassoli
DOI:10.1039/c6ob01591c
日期:——
species (ROS) is both a consequence and driver of the upregulated metabolism and proliferation of transformed cells. The resulting increase in oxidativestress is postulated to saturate the cellular antioxidant machinery, leaving cancer cells susceptible to agents that further elevate their intracellular oxidativestress. Several small molecules, including the marine natural product cribrostatin 6, have