Vnímání, kauzalita a pozornost Roger Bacon a Petr Olivi

[Sensation, Causality, and Attention: Roger Bacon and Peter Olivi] This paper investigates what conditions are to be met for sensory perception to occur. It introduces two diff erent theories of perception that were held by two medieval Franciscan thinkers — namely, Roger Bacon (1214/1220–1292) and Peter Olivi (ca. 1248–1298). Bacon analyses especially the causal relation between the object and the sensory organ in his doctrine of the multiplication of species. In his view, a necessary condition of perception is the reception of the species in a fully disposed sensory organ. On the contrary, Olivi stresses the active role of the sensory power. A necessary condition of sensation is the aspectus — i.e. the focus of our power’s attention on the object. Furthermore, the paper investigates whether and how each of the two thinkers can deal with the arguments proposed by his opponent — namely whether Bacon’s theory is able to explain attention and what the causal role of the object in Olivi’s theory is

Evolution of a Strategy for the Enantioselective Total Synthesis of (+)-Psiguadial B

(+)-Psiguadial B is a diformyl phloroglucinol mero­terpenoid that exhibits antiproliferative activity against the HepG2 human hepatoma cancer cell line. This full account details the evolution of a strategy that culminated in the first enantio­selective total synthesis of (+)-psiguadial B. A key feature of the synthesis is the construction of the <i>trans</i>-cyclo­butane motif by a Wolff rearrangement with in situ catalytic, asymmetric trapping of the ketene. An investigation of the substrate scope of this method to prepare enantioenriched 8-aminoquinolinamides is disclosed. Three routes toward (+)-psiguadial B were evaluated that featured the following key steps: (1) an <i>ortho</i>-quinone methide hetero-Diels–Alder cyclo­addition to prepare the chroman framework, (2) a Prins cyclization to form the bridging bicyclo[4.3.1]­decane system, and (3) a modified Norrish–Yang cyclization to generate the chroman. Ultimately, the successful strategy employed a ring-closing meta­thesis to form the seven-membered ring and an intramolecular <i>O</i>-arylation reaction to complete the polycyclic framework of the natural product