The 1,2,3‐triazole has been successfully utilized as an amide bioisostere in multiple therapeutic contexts. Based on this precedent, triazole analogues derived from VX‐809 and VX‐770, prominent amide‐containing modulators of the cystic fibrosis transmembrane conductance regulator (CFTR), were synthesized and evaluated for CFTR modulation. Triazole 11, derived from VX‐809, displayed markedly reduced efficacy in F508del‐CFTR correction in cellular TECC assays in comparison to VX‐809. Surprisingly, triazole analogues derived from potentiator VX‐770 displayed no potentiation of F508del, G551D, or WT‐CFTR in cellular Ussing chamber assays. However, patch clamp analysis revealed that triazole 60 potentiates WT‐CFTR similarly to VX‐770. The efficacy of 60 in the cell‐free patch clamp experiment suggests that the loss of activity in the cellular assay could be due to the inability of VX‐770 triazole derivatives to reach the CFTR binding site. Moreover, in addition to the negative impact on biological activity, triazoles in both structural classes displayed decreased metabolic stability in human microsomes relative to the analogous amides. In contrast to the many studies that demonstrate the advantages of using the 1,2,3‐triazole, these findings highlight the negative impacts that can arise from replacement of the amide with the triazole and suggest that caution is warranted when considering use of the 1,2,3‐triazole as an amide bioisostere.

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This Letter describes the synthesis and SAR, developed through an iterative analogue library approach, of a novel series of selective M1 mAChR antagonists for the potential treatment of Parkinson's disease, dystonia and other movement disorders. Compounds in this series possess M1 antagonist IC(50)s in the 441nM-19microM range with 8- to >340-fold functional selectivity versus rM2-rM5.

Allosteric ligands within a given chemotype can have the propensity to display a wide range of pharmacology, as well as unexpected changes in GPCR subtype selectivity, typically mediated by single-atom modifications to the ligand. Due to the unexpected nature of these “molecular switches”, chemotypes with this property are typically abandoned in lead optimization. Recently, we have found that in vivo oxidative metabolism by CYP 450 s can also engender molecular switches within allosteric ligands, changing the mode of pharmacology and leading to unwanted toxicity. We required a higher-throughput approach to assess in vivo metabolic molecular switches, and we turned to a “synthetic liver”, a 96 well kit of biomimetic catalysts (e.g., metalloporphyrins) to rapidly survey a broad panel of synthetic CYP 450 s’ ability to oxidize/“metabolize” an mGlu 5 PAM (VU0403602) known to undergo an in vivo CYP 450 -mediated molecular switch. While the synthetic CYP 450 s did generate a number of oxidative “metabolites” at known “hot spots”, several of which proved to be pure mGlu 5 PAMs comparable in potency to the parent, the known CYP 450 -mediated in vivo ago-PAM metabolite, namely, VU0453103, was not formed. Thus, this technology platform has potential to identify hot spots for oxidative metabolism and produce active metabolites of small-molecule ligands in a high-throughput, scalable manner.