An efficient and user-friendly palladium(II) precatalyst, POxAP (Post-Oxidative-Addition Precatalyst), was identified for use in Fukuyama cross-coupling reactions. Suitable for storage under air, the POxAP precatalyst allowed the reaction between thioesters and organozinc reagents with turnover numbers of ≈ 90,000. A series of 23 ketones were obtained with yields ranging from 53 to 99%. As proof of efficacy, an alternative approach was developed for the synthesis of a key-precursor of the natural product isoprekinamycin. PdCl(Ph)(PPh3)2 (0.1 mL, 1.4 × 10 −3 M in THF/toluene) was used.

Recently, anandamide (AEA) analogues have been well recognized for its potent neuroprotective effects in counteracting the deterioration of Alzheimer's disease (AD) brains through multiple pathological processes. In our previous studies, dipotassium N-stearoyltyrosinate (NSTK), an AEA analogue synthesized by our laboratory was reported to exert significant efficacy through multiple interventions. Within this study, the amyloid precursor protein (APP)/presenilin-1 (PS1)/Tau mouse (3×Tg-AD) model was used to explore further the neuroprotective effects of NSTK and its underlying mechanisms. NSTK could increase spontaneous locomotor activity in the open field and low anxiety-like behavior in the elevated plus maze, and improve the spatial memory deficits in the Morris water maze. The biochemical analysis suggested that NSTK could decrease Aβ deposition, abnormal tau aggregation, and the expressions of p-APP Thr668, PS1 and p-tau Ser202/Thr205 in the hippocampus of 3×Tg-AD mice. Consistently, NSTK could reduce the level of malondialdehyde, increase the activity of superoxide dismutase and catalase. Up-regulation of Bcl-2, and down-regulation of BAX, caspase-3 and inflammatory cytokines also occurred in the hippocampus of 3×Tg-AD mice after treatment with NSTK. Thus, NSTK could intervene in multiple pathological processes of AD and would be a drug candidate against AD.

Recently developed for the Fukuyama reaction, post-oxidative addition precatalysts (POxAPs) are also very efficient in catalyzing Negishi cross-coupling reactions between organohalides and organozinc reagents. Using very low catalyst loadings, POxAPs show similar catalytic activities to those of classical precatalysts such as XPhos Pd G4 or PEPPSI-IPr, with turnover numbers of up to 93,000. POxAPs are easily prepared, are stable to air and moisture, tolerate a wide range of functional groups in the Negishi cross-coupling reaction and contribute advantageously to the arsenal of organic chemists in terms of Pd precatalysts.