Catalytic Room-Temperature C-N Coupling of Amides and Isocyanates by Using Mechanochemistry.

A mechanochemical route is developed for room-temperature and solvent-free derivatization of different types of amides into carbamoyl isatins (up to 96 % conversion or yield), benzamides (up to 81 % yield), and imides (up to 92 % yield). In solution, this copper-catalyzed coupling either does not take place or requires high temperatures at which it may also be competing with alternative thermal reactivity, highlighting the beneficial role of mechanochemistry for this reaction. Such behavior resembles the previously investigated coupling with sulfonamide substrates, suggesting that this type of C-N coupling is an example of a mechanochemically favored reaction, for which mechanochemistry appears to be a favored environment over solution.

Total synthesis of neuroprotectin D1 analogues derived from omega-6 docosapentaenoic acid (DPA) and adrenic acid (AdA) from a common pivotal, late-stage intermediate.

The first total synthesis of three omega-6 dihydroxylated (E,E,Z)-docosatrienes has been successfully achieved employing a flexible strategy. The key features encompass a Boland semireduction, to create the (E,E,Z)-triene via an (E,E)-ynediene, and a selective deprotection of a tris(tert-butyldimethylsilyl) ether. The main advantage of the present strategy over previous syntheses of noncyclic dihydroxylated PUFA metabolites derived from docosahexaenoic and arachidonic acids comes from the introduction of the polar head chain at the very end of the synthesis from an advanced, pivotal aldehyde. In terms of divergency this enables late-stage modification of the head group.

A versatile and stereocontrolled total synthesis of dihydroxylated docosatrienes containing a conjugated E,E,Z-triene.

A versatile strategy featuring a Colvin rearrangement, hydrozirconation, a Sonogashira cross-coupling reaction and a Z-selective Wittig olefination, was successfully developed for the construction of a conjugated E,E,Z-triene subunit, flanked on both sides by two Z-allylic hydroxyl groups. This chemical pattern is found in many endogenous lipid metabolites such as maresin 1 (MaR1), neuroprotectin D1 (NPD1), and its aspirin triggered-isomer AT-NPD1, which not only counter-regulate inflammation but also actively orchestrate (at nanomolar doses) the resolution and termination program of acute inflammation while promoting wound healing, return to homeostasis and neuroprotection. Unlike previous approaches, the advantages of the present strategy are obvious, as it allows us to modify the nonpolar tail, the carboxylated head or both ends of the molecule without repeating the whole synthetic sequence (about 26-34 steps according to the literature). Thus, the first total syntheses of NPD1 methyl ester epimer (which can also be considered as an enantiomer of AT-NPD1) and its n-3 docosapentaenoic acid derived analogue were achieved from a highly functionalized and late advanced pivotal intermediate. This innovative route may be easily adapted to gain access to other dihydroxylated metabolites and analogues of polyunsaturated fatty acids containing a conjugated E,E,Z-triene subunit. Different epimers/diastereoisomers may be obtained by purchasing the suitable optically pure (S)- and/or (R)-1,2,4-butanetriol(s) as a chiral pool for both stereogenic centers.

Deprotonative metallation of ferrocenes using mixed lithium-zinc and lithium-cadmium combinations.

A mixed lithium-cadmium amide and a combination of lithium and zinc amides were reacted with a range of ferrocenes; deprotonative mono- or dimetallation in general occurred chemoselectively at room temperature, as evidenced by subsequent quenching with iodine.