Enantioselective synthesis and pharmacology of 11-hydroxy-(1'S,2'R)-dimethylheptyl-delta 8-THC

Natural cannabinoids: templates for drug discovery

Recent studies have elucidated the biosynthetic pathway of cannabinoids and have highlighted the preference for a C-3 n-pentyl side chain in the most prominently represented cannabinoids from Cannabis sativa and their medicinally important decarboxylation products. The corresponding C-3 n-propyl side chain containing cannabinoids are also found, although in lesser quantities. Structure-activity relationship (SAR) studies performed on Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the key psychoactive ingredient of Cannabis, and its synthetic analogues have identified the C-3 side chain as the key pharmacophore for ligand affinity and selectivity for the known cannabinoid receptors and for pharmacological potency. Interestingly, the terminal n-pentyl saturated hydrocarbon side chain of endocannabinoids also plays a corresponding crucial role in conferring similar properties. This review briefly summarizes the biosynthesis of cannabinoids and endocannabinoids and focuses on their side chain SAR.

Structure-activity relationships for 1',1'-dimethylalkyl-Delta8-tetrahydrocannabinols

A series of 1',1'-dimethylalkyl-Delta(8)-tetrahydrocannabinol analogues with C-3 side chains of 2-12 carbon atoms has been synthesized and their in vitro and in vivo pharmacology has been evaluated. The lowest member of the series, 1',1'-dimethylethyl-Delta(8)-THC (8, n=0) has good affinity for the CB(1) receptor, but is inactive in vivo. The dimethylpropyl (8, n=1) through dimethyldecyl (8, n=8) all have high affinity for the CB(1) receptor and are full agonists in vivo. 1',1'-Dimethylundecyl-Delta(8)-THC (8, n=9) has significant affinity for the receptor (K(i)=25.8+/-5.8 nM), but has reduced potency in vivo. The dodecyl analogue (8, n=10) has little affinity for the CB(1) receptor and is inactive in vivo. A quantitative structure-activity relationship study of the side chain region of these compounds is consistent with the concept that for optimum affinity and potency the side chain must be of a length which will permit its terminus to loop back in proximity to the phenolic ring of the cannabinoid.

1-Methoxy-, 1-deoxy-11-hydroxy- and 11-hydroxy-1-methoxy-Delta(8)-tetrahydrocannabinols: new selective ligands for the CB2 receptor

Three series of new cannabinoids were prepared and their affinities for the CB(1) and CB(2) cannabinoid recptors were determined. These are the 1-methoxy-3-(1',1'-dimethylalkyl)-, 1-deoxy-11-hydroxy-3-(1',1'-dimethylalkyl)- and 11-hydroxy-1-methoxy-3-(1',1'-dimethylalkyl)-Delta(8)-tetrahydrocannabinols, which contain alkyl chains from dimethylethyl to dimethylheptyl appended to C-3 of the cannabinoid. All of these compounds have greater affinity for the CB(2) receptor than for the CB(1) receptor, however only 1-methoxy-3-(1',1'-dimethylhexyl)-Delta(8)-THC (JWH-229, 6e) has effectively no affinity for the CB(1) receptor (K(i)=3134+/-110nM) and high affinity for CB(2) (K(i)=18+/-2nM).