Magnus Gustafsson

Complete regioselective addition of grignard reagents to pyrazine N-oxides, toward an efficient enantioselective synthesis of substituted piperazines

A conceptually new one-pot strategy for the synthesis of protected substituted piperazines via the addition of Grignard reagents to pyrazine N-oxides is presented. This strategy is high yielding (33-91% over three steps), step-efficient, and fast. The synthesized N,N-diprotected piperazines are convenient to handle and allow for orthogonal deprotection at either nitrogen for selective transformations. In addition, this is a synthetic route to enantiomerically enriched piperazines by using a combination of phenyl magnesium chloride and (-)-sparteine, which resulted in enantiomeric excesses up to 83%.

The Regio‐ and Stereoselective Synthesis of trans‐2,3‐Dihydropyridine N‐oxides and Piperidines

Reactivity N-Own: Pyridine N-oxides can be used for the complete regio- and stereoselective synthesis of trans-substituted piperidines. The sequential addition of Grignard reagents and aldehydes or ketones to pyridine N-oxides yields a complete regio- and stereoselective trans 2,3-addition reaction in high yields, and the substituted 2,3-dihydropyridine N-oxide can be reduced to form 2,3-trans-substituted piperidines (see scheme).

Characterization of Highly Efficacious Allosteric Agonists of the Human Calcium-Sensing Receptor

We discovered structurally novel human calcium-sensing receptor (CaSR) allosteric agonists and compared their pharmacology to phenylalkylamine calcimimetics. 1-Benzothiazol-2-yl-1-(2,4-dimethyl-phenyl)-ethanol (AC-265347) activated CaSR signaling in cellular proliferation and phosphatidylinositol (PI) hydrolysis assays with potencies of 30 and 10 nM, respectively. (S)-1-Benzothiazol-2-yl-1-(2,4-dimethyl-phenyl)-ethanol) [(S)-AC-265347], the S-enantiomer of AC-265347, was approximately 10- to 20-fold more potent than (R)-1-benzothiazol-2-yl-1-(2,4-dimethyl-phenyl)-ethanol) [(R)-AC-265347]. The phenylalkylamines cinacalcet and calindol had activity similar to that of AC-265347 in cellular proliferation assays but less activity in PI assays. All compounds had reduced activity when extracellular Ca2+ was removed, indicating that they cooperate with Ca2+ to activate CaSRs, and all activated CaSR isoforms with the N-terminal extracellular domain deleted, indicating that they interact with the transmembrane domains. In both cases, AC-265347 and therefore (S)-AC-265347 were significantly more efficacious than the phenylalkylamines. Mutations E837A7.39 and I841A7.43 strongly reduced phenylalkylamine-induced signaling, but not AC-265347- or (S)-AC-265347-induced signaling, suggesting different modes of binding. AC-265347 and (S)-AC-265347 stimulated significantly greater responses than cinacalcet or calindol at each of four loss-of-function human polymorphic CaSR variants. AC-265347 did not inhibit the CYP2D6 cytochrome P450 isozyme, unlike cinacalcet, which is a potent CYP2D6 inhibitor. In rats, AC-265347, (S)-AC-265347, and (R)-AC-265347 each reduced serum parathyroid hormone (PTH) with a rank order potency correlated with their in vitro potencies. AC-265347 and (S)-AC-265347 also reduced plasma ionizable calcium ([Ca2+]o). AC-265347 was orally active, and its plasma concentrations correlated well with its effects on serum PTH. Thus, these highly efficacious CaSR allosteric agonists represent leads for developing therapeutic agents with potential advantages over existing therapies.

Broad modulation of neuropathic pain states by a selective estrogen receptor beta agonist

The effects of estrogens on pain perception remain controversial. In animal models, both beneficial and detrimental effects of non-selective estrogens have been reported. ERb-131 a non-steroidal estrogen receptor beta ligand was evaluated in several pain animal models involving nerve injury or sensitization. Using functional and binding assays, ERb-131 was characterized as a potent and selective estrogen receptor beta agonist. In vivo, ERb-131 was devoid of estrogen receptor alpha activity as assessed in a rat uterotrophic assay. ERb-131 alleviated tactile hyperalgesia induced by capsaicin, and reversed tactile allodynia caused by spinal nerve ligation and various chemical insults. Moreover, ERb-131 did not influence the pain threshold of normal healthy animals. Thus, estrogen receptor beta agonism is a critical effector in attenuating a broad range of anti-nociceptive states.

Differential modulation of inflammatory pain by a selective estrogen receptor beta agonist

To understand the contribution of the estrogen receptor beta, the potent and selective agonist ERb-131 was evaluated in animal models of inflammatory pain. In paradigms of acute and persistent inflammatory pain, ERb-131 did not alleviate the nociception induced by either carrageenan or formalin. However, in the chronic complete Freunds adjuvant model, ERb-131 resolved both inflammatory and hyperalgesic components. Thus, ERb-131 is sufficient to alleviate chronic but not acute inflammatory pain states.

General combinatorial synthesis of tertiary amines on solid support. A novel conditional release strategy based on traceless linking at nitrogen

Abstract A novel solid phase synthesis of tertiary amines involving iodide-induced cleavage of the N O bond of resin bound alkoxyammonium intermediates is described. The quaternary intermediates were assembled via sequential reductive aminations followed by alkylation. Cleavage from the solid support was induced by iodide ion or base, to afford the target tertiary amines in excellent purity.

Discovery of a class of calcium sensing receptor positive allosteric modulators; 1-(benzothiazol-2-yl)-1-phenylethanols.

1-(Benzothiazol-2-yl)-1-(4-chlorophenyl)ethanol (1) was identified as a positive allosteric modulator (PAM) of the CaSR in a functional cell-based assay. This compound belongs to a class of compounds that is structurally distinct from other known positive allosteric modulators, for example, the phenylalkylamines cinacalcet, a modified analog (13) potently suppressed parathyroid hormone (PTH) release in rats, consistent with its profile as a PAM of CaSRs.

392 A SELECTIVE ESTROGEN RECEPTOR BETA AGONIST MODULATES NEUROPATHIC AND INFLAMMATORY PAIN STATES

Background and aims. The effects of estrogens on pain perception remain quite controversial. Depending on the animal models, both beneficial and detrimental effects of non-selective estrogens have been reported in the literature. Further, the results of multiple human clinical trials examining the potential beneficial effects of estrogens in breast, bone, pelvic pain have been inconclusive as well. While the underlying mechanisms for these discrepancies are not understood, we believe they are likely to arise from the lack of selectivity of estrogens for their two cognate receptors, the nuclear hormone receptors ER alpha and ER beta. Results and conclusions. Using a proprietary functional cell-based platform technology (R-SAT : Receptor Selection and Amplification Technology), non steroidal ER beta pharmacophores were identified. They define two classes of small molecule agonists, with low nanomolar affinity for ER beta and a high degree of selectivity (>100–1000-fold) versus ER alpha and other nuclear receptors. A prototype lead molecule, ERb-131, was evaluated in several pain animal models involving nerve injury or sensitization. ERb-131 reversed tactile allodynia caused by spinal nerve ligation (Chung model) and chemical insults. ERb-131 also alleviated tactile or thermal hyperalgesia in both acute and chronic inflammation models (capsaicin, CFA, formalin). Finally, ERb-131 did not influence the pain threshold of normal healthy animals. Thus, ER beta agonism is a critical effector in the mediation of broad anti-nociceptive states.