Synthetic cannabinoid receptor agonists (SCRAs) are one of the largest groups of new psychoactive substances monitored in Europe. SCRAs are known to typically exert higher cannabinoid activity than tetrahydrocannabinol from cannabis, thereby entailing a greater health risk. Both Cumyl‐PEGACLONE and 5F‐Cumyl‐PEGACLONE were not controlled by the national legislation upon their first detection in Germany in 2016 and 2017, respectively, and have been linked to several fatalities. In this study, the CB1 receptor activity of these compounds, together with two newly synthesized structural isomers (Cumyl‐PEGACLONE ethylbenzyl isomer and n‐propylphenyl isomer), was assessed using two different in vitro receptor‐proximal bioassays, monitoring the recruitment of either β‐arrestin2 (β‐arr2) or a modified G protein (mini‐Gαi) to the activated CB1 receptor. In terms of both potency and relative efficacy, Cumyl‐PEGACLONE and 5F‐Cumyl‐PEGACLONE were found to exert strong CB1 activation, with sub‐nanomolar EC50 values and efficacy values exceeding those of the reference agonist JWH‐018 threefold (β‐arr2 assay) or almost twofold (mini‐Gαi assay). The ethylbenzyl and n‐propylphenyl isomers exhibited a strongly reduced CB1 activity (EC50 values >100 nM; efficacy <40% relative to JWH‐018), which is hypothesized to originate from steric hindrance in the ligand‐binding pocket. None of the evaluated compounds exhibited significant biased agonism. In conclusion, the functional assays applied here allowed us to demonstrate that 5‐fluorination of Cumyl‐PEGACLONE is not linked to an intrinsically higher CB1 activation potential and that the ethylbenzyl and n‐propylphenyl isomers yield a strongly reduced CB1 activation.

A readily available cyclic carbamate 1 functions as a general precursor to a range of functionalized piperidine products via a new Pd-catalyzed annulation strategy. An asymmetric catalytic variant provides a rapid and efficient means to access these heterocycles with high to excellent levels of enantiocontrol. Finally, these richly functionalized compounds are amenable to further chemoselective elaboration.

The regioselective addition of nucleophiles to pyridinium salts generates an intermediate enol-ether, which can be hydrolyzed in situ to provide a range of dihydropyridones. Certain Grignards have shown inherent differences in the regioselectivity of addition to these salts, and this difference can be tuned to give single regioisomeric addition products. The dihydropyridone products can be further manipulated in many ways using standard transformations.

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