Synthesis of unsymmetrical thioethers using an uncommon base-triggered 1,5-thiol transfer reaction of 1-bromo-2-alkylthiolcarbonates.

Described herein is a convenient, odorless, metal-free, one-pot strategy for the synthesis of unsymmetrical thioethers. The key step in this new strategy is a base-catalyzed 1,5-thiol transfer reaction via a pseudointramolecular mechanism of a 1-bromo-2-alkylthiolcarbonate, which is itself obtained through a straightforward microwave-assisted thioalkylation of a 1,2-cyclic-thionocarbonate precursor with an appropriate alkyl bromide. The starting 1,2-cyclic-thionocarbonates are easily obtained from the corresponding diols. When a propargylthiolcarbonate constitutes the key alkylthiolcarbonate 1,5-shift precursor, a copper-mediated dipolar cycloaddition reaction ("click") with azide partners is rendered possible. This increases the versatility of the approach, as a very large variety of complex triazole-tethered substrates can potentially be integrated into the target unsymmetrical thioether final products. As an example of the scope of the reaction, four 1,5-shift reactions have been triggered simultaneously from a sugar-derived tetrathiolcarbonate precursor using base catalysis, to allow four 6-thioglucose moieties to be installed (78% yield for each sugar unit) onto a 1,3-alternate thiacalix[4]arene scaffold in a one-pot transformation.

[French military nurses during the First World War (1914-1918)]. / Les infirmiers militaires français dans la guerre 1914-1918.

In 1914, beingthe heirs of the ambulance soldiers who had been created during the time of the Empire, the military males-nurses were overwhelmed by the armies huge needs in paramedics. Facing both the callings of commandment which demanded the recruitment of soldiers and the necessity--which had been set up as a duty by the health service--to attend the doctors, the military male-nurse gave way, in 1918 to a new comer: the female military nurse.