A library of gold(I) chloride complexes with phosphine ligands incorporating pendant (thio)urea and squaramide H‐bond donors was prepared with the aim of promoting chloride abstraction from Au(I) via H‐bonding. In the absence of silver additives, complexes bearing squaramides and trifluoromethylated aromatic ureas displayed good catalytic activity in the cyclization of N‐propargyl benzamides, as well as in a 1,6‐enyne cycloisomerization, a tandem cyclization‐indole addition reaction and the hydrohydrazination of phenylacetylene. Kinetic studies and DFT calculations indicate that the energetic span of the reaction is accounted by both the chloride abstraction step, facilitated by the bidentate H‐bond donor via an associative mechanism, and the subsequent cyclization step.
An outline of the advantages, in terms of sustainability,
of Deep
Eutectic Solvents (DESs) is provided, by analyzing some of the most
popular DESs, obtained by the combination of choline chloride, as
a hydrogen bond acceptor, and six hydrogen bond donors. The analysis
is articulated into four main issues related to sustainability, which
are recurrently mentioned in the literature, but are often taken for
granted without any further critical elaboration, as the prominent
green features of DESs: their low toxicity, good biodegradability,
renewable sourcing, and low cost. This contribution is intended to
provide a more tangible, evidence-based evaluation of the actual green
credentials of the considered DESs, to reinforce or question their
supposed sustainability, also in mutual comparison with one another.
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