RESUMEN
A novel strategy for the synthesis of Aspidosperma alkaloids has been achieved via a photoredox-initiated [2+2]/retro-Mannich reaction of tryptamine-substituted enaminones as a key step. The developed chemistry has been applied to the construction of the core tetracycle of Aspidosperma alkaloids (±)-aspidospermidine and (±)-limaspermidine.
RESUMEN
A novel method for the concise synthesis of cyclohepta[b]indoles in high yields was developed. The method involves a visible-light-induced, photocatalyzed [2+2]-cycloaddition/ retro-Mannich-type reaction of enaminones. Experimental and computational studies suggested that the reaction is a photoredox process initiated by single-electron oxidation of an enaminone moiety, which undergoes subsequent cyclobutane formation and rapidly fragmentation in a radical-cation state to form cyclohepta[b]indoles.
RESUMEN
Electrochemical actuators are devices that convert electrical energy into mechanical energy via electrochemical processes. They are used in soft robotics, artificial muscles, micropumps, sensors, and other fields. The design of flexible and stable electrode materials remains a major challenge. MXenes, an emerging family of 2D materials, have found applications in energy storage. Here, we report an actuator device using MXene (Ti3C2Tx) as a flexible electrode material. The electrode in 1 M H2SO4 electrolyte exhibits a curvature change up to 0.083 mm-1 and strain of 0.29%. Meanwhile, the MXene-based actuator with a symmetric configuration separated by gel electrolyte (PVA-H2SO4) has curvature and strain changes up to 0.038 mm-1 and 0.26% with excellent retention after 10,000 cycles. In situ X-ray diffraction analysis demonstrates that the actuation mechanism is due to the expansion and shrinkage of the interlayer spacing of MXenes. This research shows promise of this new family of materials for electrochemical actuators.
RESUMEN
A stereoselective three-component coupling reaction of allylzinc bromide, silyl glyoxylate, and a ß-lactone has been developed. This has been successfully applied to the enantio- and diastereoselective synthesis of the fully functionalized furopyran moiety of azadirachtins.