Axially Chiral Cannabinoids: Design, Synthesis, and Cannabinoid Receptor Affinity

The resorcinol-terpene phytocannabinoid template is a privileged scaffold for the development of diverse therapeutics targeting the endocannabinoid system. Axially chiral cannabinols (axCBNs) are unnatural cannabinols (CBNs) that bear an additional C10 substituent, which twists the cannabinol biaryl framework out of planarity creating an axis of chirality. This unique structural modification is hypothesized to enhance both the physical and biological properties of cannabinoid ligands, thus ushering in the next generation of endocannabinoid system chemical probes and cannabinoid-inspired leads for drug development. In this full report, we describe the philosophy guiding the design of axCBNs as well as several synthetic strategies for their construction. We also introduce a second class of axially chiral cannabinoids inspired by cannabidiol (CBD), termed axially chiral cannabidiols (axCBDs). Finally, we provide an analysis of axially chiral cannabinoid (axCannabinoid) atropisomerism, which spans two classes (class 1 and 3 atropisomers), and provide first evidence that axCannabinoids retain─and in some cases, strengthen─affinity and functional activity at cannabinoid receptors. Together, these findings present a promising new direction for the design of novel cannabinoid ligands for drug discovery and exploration of the complex endocannabinoid system.

Copper-catalyzed oxidative trifluoromethylation of terminal alkynes and aryl boronic acids using (trifluoromethyl)trimethylsilane

Trifluoromethylated acetylenes and arenes are widely applicable in the synthesis of pharmaceuticals and agrochemicals. In 2010, our group has reported the copper-mediated oxidative trifluomethylation of terminal alkynes and aryl boronic acids. This method allows a wide range of functional group tolerant trifluoromethylated acetylenes and arenes to be easily prepared. After the preliminary mechanistic studies of the oxidative trifluoromethylation of terminal alkyne, an efficient copper-catalyzed oxidative trifluoromethylation of terminal alkynes and aryl boronic acids has been developed. The catalytic protocol is successfully achieved by adding both the substrate and a portion of CF(3)TMS slowly using a syringe pump to the reaction mixture.

Synthesis and computational analysis of densely functionalized triazoles using o-nitrophenylalkynes

Dipolar cylcoadditions with azides using a series of o-nitrophenylethynes and disubstituted alkynes were studied experimentally and computationally. Density functional theory computations reveal the steric and electronic parameters that control the regioselectivity of these cycloadditions. Several new substrates were predicted that would either give enhanced regiocontrol or invert the regiochemical preference. Experimentally, the alkynes were screened in the [3 + 2] cycloaddition with benzyl azide. Of the 11 alkynes screened experimentally, the acetylenes containing halogen substitution directly on the alkyne provided the highest levels of regioselectivity. These haloalkynes were also shown to tolerate variation of the azide moiety with continued good levels of regioselectivity in most cases. Diverse functional groups can be incorporated through the cycloaddition process and their subsequent orthogonal modification was demonstrated.