Sequential alcohol oxidation/putative homo Claisen-Tishchenko-type reaction to give esters: a key process in accessing novel biologically active lactone macrocycles

We report an efficient methodology for the direct oxidative esterification of primary alcohols to diether-esters using pyridinium chlorochromate (PCC). Numerous studies were carried out to probe the reaction mechanism and at the same time optimize the reaction conditions. The reaction could be conducted with 1 equivalent of PCC and 1 equivalent of BF3 center dot OEt2. Indications based on literature precedent were that the reaction may proceed via a sequential alcohol oxidation to the aldehyde followed by a putative Cr or boron catalyzed Claisen-Tishchenko-type reaction. Using this efficient methodology, we synthesized a family of novel diether-esters in very good yields; some of these molecules were subsequently tested against both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). In addition, we also disclose a new synthetic strategy for the synthesis of lactam macrocycles with potential biological activity. This methodology included the regioselective borylation of the ester substrate and a subsequent Suzuki-Miyaura coupling to obtain the desired lactam macrocycle.

Valuing landscape identity of local inhabitants through a tourism discourse

Landscape, people and identity Landscape is about the interaction of a place or an area with people, which is reflected in the material interaction of people creating or shaping the landscape as well as in their mental perception, valuation and symbolic meaning of that landscape (Cosgrove 1998). This mutual and dynamic interaction forms the fundamental principle of the concept of landscape identity. Landscape identity has been described in scientific literature as a concept to bridge the physical, social and cultural aspects of landscapes. Also policy documents related with landscape and heritage (for example the UNESCO World Heritage Convention, the European Landscape Convention, the Faro Convention) are mentioning identity and landscape as key concepts. In those examples, landscape identity can refer to either the landscape itself - its features that makes the landscape unique (thus the landscape character), or to the social and personal construction. However, there is an interdependency between those two perspectives that needs to be conceptualised. Landscape identity is therefore defined as the multiple ways and dynamic relation between landscape and people (Loupa Ramos et al 2016).