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The tin salt Sn(NTf2)4 (Tf=trifluoromethanesulfonyl) is an efficient catalyst for the selective and ring‐size‐specific cycloisomerization of highly substituted 1,6‐dienes to give six‐membered‐ring carbocycles (see scheme; X=C(CO2Et)2, C(CO2Me)2 C(CN)(CO2Et), etc.). This is the first Lewis acid catalyzed cycloisomerization of this type of substrate.

Di-and Tetra-nuclear Complexes with Bis(dipheny1phosphino)amide and Bis(diphenylphosphino1methanide as Bi-and Tri-dentate Ligands. X-Ray Structures of [(Ph3P)(03CIO)AgN(Ph2PAuPPh2)2NAg(OC103)( PPh3)] and

Mono-and dicationic palladium efficiently catalyses the cycloisomerisation of bis allyl substrates with high chemo-, regio-and enantioselectivities (60% ee).Unsaturated cycloalkanes are an integral part of many natural products and their preparation is of permanent interest in organic synthesis. One important method under the conditions of homogeneous catalysis concerns the (atom economically) interesting cycloisomerisation 1 of alkynes 2 and 1,3-dienes. 3 In this context, the cycloisomerisation of 1,6-dienes (diallylmalonates, e.g. 1) described by Grigg and coworkers 4 has been shown to lead to unsaturated five-membered rings with late transition metals, and, more precisely, palladium acetate in chloroform containing HCl gave selectively 1,2-dimethylcyclopent-2-enes 2 whereas rhodium(I) chloride triphenylphosphine complexes catalyse the formation of 1-methyl-2-methylenecyclopentanes 3. It seemed to us interesting to develop this reaction for several reasons. First of all, the starting material is easily available and it is possible to introduce heteroatoms (N, O, S, Si, and others) between the allyl groups, allowing an access to carbo-and heterocylic five-membered rings. On the other hand, the generation of a chiral centre is an opportunity to study enantioselective catalytic transformations, provided the system tolerates chiral ligands. Now, we are able to show that palladium complexes can catalyse both reactions efficiently with high regioselectivity and, more importantly, that the addition of nitrogen centered chelating ligands does not alter the reactivity thus permitting enantioselective palladium catalysis with chiral complexes.It is well known that cationic palladium complexes favour the dimerisation of ethylene compounds. 5 When 1 was treated in chloroform at 60°C with cationic [(MeCN) 3 PdCl]BF 4 generated in situ from bisacetonitrile palladium(II) chloride and AgBF 4 , 4,4-biscarboxylato-1,2-dimethylcyclopent-2-ene 2 was formed in more than 79% yield, after distillation. The compound is isomerically pure, and only trace amounts of 3 or symmetrical 4 could be detected.Scheme 1 a (MeCN) 2 PdCl 2 (0.05 equiv.), MeCN, AgBF 4 (0.045 equiv.) 20°C, filtration and CHCl 3 , 60°C, 18h, 2 79% (distilled); b (MeCN) 4 Pd(BF 4 ) 2 (0.05 equiv.), CHCl 3 , 20°C, 8h, 3 (39%) (NMR).The reaction course and the yield of 2 is not notably altered when the cationic catalyst is coordinated to polypyrazoles, e.g. the methano bis pyrazole (CH 3 ) 2 C(pz) 2 5, prepared from (MeCN) 2 PdCl 2 in dichloromethane. 6 Though the exact mechanism for the formation of 2 is not yet clear, 4 it is trivial that at least two hydride migrations must be involved. It has been shown that dicationic palladium species favour carbocationic rearrangements of substituted olefins 7 but, at the same time, are highly selective dimerisation catalysts of styrene when coordinated to pyridine ligands. 8 In the latter reaction no double bond migration was observed.When the catalyst precursor PdCl 2 -5 was treated with 2 equivalents of silver salt, presumably ...

Fresh produce within vertical farming systems grows vertically in different layers stacked atop each other, thus allowing for the efficient use of space. As the environment in vertical farming systems is completely controlled, neither sunlight nor soil is necessary. On the one hand, vertical farming may help to provide a healthy diet for the growing global population because it has a greater crop yield per square meter used than conventional farming; moreover, it can offer the opportunity to grow food in climatically disadvantaged areas. On the other hand, growth conditions may be perceived as unnatural and the entire vertical farming system as unsustainable. Therefore, understanding the consumers’ acceptance of vertical farming systems is important. This study is the first work to provide insights into consumers’ acceptance of three different vertical farming systems. Data are collected through an online survey of 482 consumers in Germany in February 2018. Drivers of consumer acceptance of vertical farming systems are identified through structural equation modelling. The results indicate that perceived sustainability is the major driver of consumer acceptance of vertical farming systems. The larger the system, the higher the likelihood that it will be considered as sustainable. Obviously, consumers perceive something like ecologies of scale.

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