RESUMO
Garsubellinâ A is a thirty-carbon meroterpenoid capable of enhancing the enzyme choline acetyltransferase whose decreased level is associated with the symptoms of Alzheimer's disease. Due to the potentially useful biological activity along with the novel molecular architecture, this plant metabolite has remained a popular synthetic target. Herein we report a full account of our synthetic investigations that have led to the enantioselective total synthesis of garsubellinâ A, establishing its absolute stereostructure. The protecting group-free, twelve-step synthetic route has enabled the syntheses of the natural (-)-garsubellinâ A and its unnatural (+)-antipode.
Assuntos
Doença de Alzheimer , Produtos Biológicos , Humanos , Estereoisomerismo , Terpenos/química , Colina O-Acetiltransferase/metabolismoRESUMO
Garsubellinâ A is a meroterpene capable of enhancing the enzyme choline acetyltransferase whose decreased level is believed to play a central role in the symptoms of Alzheimer's disease. Due to the potentially useful biological activity together with the novel bridged and fused cyclic molecular architecture, garsubellinâ A has garnered substantial synthetic interest, but its absolute stereostructure has been undetermined. We report here the first enantioselective total synthesis of (+)-garsubellinâ A. Our synthesis relies on stereoselective fashioning of a cyclohexanone framework and double conjugate addition of 1,2-ethanedithiol that promotes aldol cyclization to build the bicyclic [3.3.1] skeleton. The twelve-step, protecting group-free synthetic route has enabled the syntheses of both the natural (-)-garsubellinâ A and its unnatural (+)-antipode for biological evaluations.
Assuntos
Terpenos/síntese química , Produtos Biológicos/síntese química , Produtos Biológicos/química , Compostos Bicíclicos com Pontes/química , Cristalografia por Raios X , Ciclização , Conformação Molecular , Estereoisomerismo , Terpenos/químicaRESUMO
A high performance, stretchable UV sensor array was fabricated based on an active matrix (AM) device that combined field effect transistors of SWCNTs and SnO2 nanowires. The AM devices provided spatial UV sensing via the individual sensors in the array. SnO2 NW UV sensors showed an average photosensitivity of â¼10(5) and a photoconductive gain of â¼10(6) under very low UV (λ = 254 nm) power intensities of 0.02-0.04 mW cm(-2). The UV sensing performance was not deteriorated by a prestrain of up to 23% induced by radial deformation, consistent with the mechanical analysis.