Platinum catalysed hydrosilylation of propargylic alcohols.

A facile and user-friendly protocol has been developed for the selective synthesis of E-vinyl silanes derived from propargylic alcohols using a PtCl2/XPhos catalyst system. The reaction is generally high yielding and provides a single regioisomer at the ß-position with E-alkene geometry. The reaction is extremely tolerant of functionality and has a wide scope of reactivity both in terms of alkynes and silanes used. The catalyst loading has been investigated and it is found that good reactivity is observed at extremely low catalyst loadings. This methodology has also been extended to a one-pot hydrosilylation Denmark-Hiyama coupling.

Screening of a Custom-Designed Acid Fragment Library Identifies 1-Phenylpyrroles and 1-Phenylpyrrolidines as Inhibitors of Notum Carboxylesterase Activity.

The Wnt family of proteins are secreted signaling proteins that play key roles in regulating cellular functions. Recently, carboxylesterase Notum was shown to act as a negative regulator of Wnt signaling by mediating the removal of an essential palmitoleate. Here we disclose two new chemical scaffolds that inhibit Notum enzymatic activity. Our approach was to create a fragment library of 250 acids for screening against Notum in a biochemical assay followed by structure determination by X-ray crystallography. Twenty fragments were identified as hits for Notum inhibition, and 14 of these fragments were shown to bind in the palmitoleate pocket of Notum. Optimization of 1-phenylpyrrole 20, guided by structure-based drug design, identified 20z as the most potent compound from this series. Similarly, the optimization of 1-phenylpyrrolidine 8 gave acid 26. This work demonstrates that inhibition of Notum activity can be achieved by small, drug-like molecules possessing favorable in vitro ADME profiles.

Neurochemical and behavioral profiling of the selective GlyT1 inhibitors ALX5407 and LY2365109 indicate a preferential action in caudal vs. cortical brain areas.

Selective inhibitors of the glycine transporter 1 (GlyT1) have been implicated in central nervous system disorders related to hypoglutamatergic function such as schizophrenia. The selective GlyT1 inhibitors ALX5407 (NFPS) and LY2365109 {[2-(4-benzo[1,3]dioxol-5-yl-2-tert-butylphenoxy)ethyl]-methylamino}-acetic acid increased cerebrospinal fluid levels of glycine and potentiated NMDA-induced increases in dialysate levels of neurotransmitters in the prefrontal cortex (PFC) and the striatum. However, higher doses produced both stimulatory and inhibitory effects on motor performance and impaired respiration, suggesting significant involvement of cerebellar and brain stem areas. A dual probe microdialysis study showed that ALX5407 transiently elevated extracellular levels of glycine in the PFC with more sustained increases in the cerebellum. In support of these findings, immuno-staining with pan-GlyT1 and GlyT1a antibodies showed a higher abundance of immunoreactivity in the brain stem/cerebellum as compared to the frontal cortical/hippocampal brain areas in four different species studied, including the mouse, rat, monkey and human. In addition, the inhibitory effects of ALX5407 on cerebellar levels of cGMP in the mouse could be reversed by the glycine A receptor antagonist strychnine but not the glycine B receptor antagonist L-701324. We propose that the adverse events seen with higher doses of ALX5407 and LY2365109 are the result of high GlyT1 inhibitory activity in caudal areas of the brain with sustained elevations of extracellular glycine. High levels of glycine in these brain areas may result in activation of strychnine-sensitive glycine A receptors that are inhibitory on both motor activity and critical brain stem functions such as respiration.

Biomimetic synthesis of pyrone-derived natural products: exploring chemical pathways from a unique polyketide precursor.

Our biomimetic hypothesis proposes that families of diverse natural products with complex core structures such as 9,10-deoxytridachione, photodeoxytridachione and ocellapyrone A are derived in nature from a linear and conformationally strained all-( E) tetraene-pyrone precursor. We therefore synthesized such a precursor and investigated its biomimetic transformation under a variety of reaction conditions, both to the above natural products as well as to diverse isomers which we propose to be natural products "yet to be discovered". We also report herein the first synthesis of the natural product iso-9,10-deoxytridachione.

A novel oxidative rearrangement of 6-methoxypyran-2-ones.

As part of our continuing studies of pyrone-containing natural products, a series 6-methoxypyran-2-ones were synthesized. These were found to react with molecular oxygen at 20 degrees C, and this novel reaction yielded a series of highly functionalized alpha,beta-butenolides. [reaction: see text]

Discovery of a potent, dual serotonin and norepinephrine reuptake inhibitor.

The objective of the described research effort was to identify a novel serotonin and norepinephrine reuptake inhibitor (SNRI) with improved norepinephrine transporter activity and acceptable metabolic stability and exhibiting minimal drug-drug interaction. We describe herein the discovery of a series of 3-substituted pyrrolidines, exemplified by compound 1. Compound 1 is a selective SNRI in vitro and in vivo, has favorable ADME properties, and retains inhibitory activity in the formalin model of pain behavior. Compound 1 thus represents a potential new probe to explore utility of SNRIs in central nervous system disorders, including chronic pain conditions.

Synthesis of 11C-labelled (R)-OHDMI and CFMME and their evaluation as candidate radioligands for imaging central norepinephrine transporters with PET.

(R)-1-(10,11-Dihydro-dibenzo[b,f]azepin-5-yl)-3-methylamino-propan-2-ol ((R)-OHDMI) and (S,S)-1-cyclopentyl-2-(5-fluoro-2-methoxy-phenyl)-1-morpholin-2-yl-ethanol (CFMME) were synthesized and found to be potent inhibitors of norepinephrine reuptake. Each was labelled efficiently in its methyl group with carbon-11 (t(1/2)=20.4 min) as a prospective radioligand for imaging brain norepinephrine transporters (NET) with positron emission tomography (PET). The uptake and distribution of radioactivity in brain following intravenous injection of each radioligand into cynomolgus monkey was examined in vivo with PET. After injection of (R)-[(11)C]OHDMI, the maximal whole brain uptake of radioactivity was very low (1.1% of injected dose; I.D.). For occipital cortex, thalamus, lower brainstem, mesencephalon and cerebellum, radioactivity ratios to striatum at 93 min after radioligand injection were 1.35, 1.35, 1.2, 1.2 and 1.0, respectively. After injection of [(11)C]CFMME, radioactivity readily entered brain (3.5% I.D.). Ratios of radioactivity to cerebellum at 93 min for thalamus, occipital cortex, region of locus coeruleus, mesencephalon and striatum were 1.35, 1.3, 1.3, 1.2 and 1.2, respectively. Radioactive metabolites in plasma were measured by radio-HPLC. (R)-[(11)C]OHDMI represented 75% of plasma radioactivity at 4 min after injection and 6% at 30 min. After injection of [(11)C]CFMME, 84% of the radioactivity in plasma represented parent at 4 min and 20% at 30 min. Since the two new hydroxylated radioligands provide only modest regional differentiation in brain uptake and form potentially troublesome lipophilic radioactive metabolites, they are concluded to be inferior to existing radioligands, such as (S,S)-[(11)C]MeNER, (S,S)-[(18)F]FMeNER-D(2) and (S,S)-[(18)F]FRB-D(4), for the study of brain NETs with PET in vivo.

Discovery and SAR studies of novel GlyT1 inhibitors.

Inhibition of the glycine transporter GlyT1 is a potential strategy for the treatment of schizophrenia. A novel series of GlyT1 inhibitors and their structure-activity relationships (SAR) are described. Members of this series are highly potent and selective transport inhibitors which are shown to elevate glycine levels in cerebrospinal fluid.

Discovery of novel and selective tertiary alcohol containing inhibitors of the norepinephrine transporter.

A novel series of tertiary alcohol containing 2-substituted benzyl morpholines have been discovered as potent and selective inhibitors of the norepinephrine transporter. Efficient synthetic routes were developed featuring a highly diastereoselective nucleophilic addition of benzyl Grignard reagents to enantiopure (4-benzylmorpholin-2-yl)phenylmethanone (11) as the key synthetic step. In vitro binding affinity for the norepinephrine, dopamine and serotonin transporters and in vivo examination of a select compound (16) in a pharmacodynamic animal model for norepinephrine reuptake inhibition are presented.

1-Aryl-3,4-dihydro-1H-quinolin-2-one derivatives, novel and selective norepinephrine reuptake inhibitors.

A novel series of 1-aryl-3,4-dihydro-1H-quinolin-2-ones have been discovered as potent and selective norepinephrine reuptake inhibitors. Efficient synthetic routes have been developed which allow for the multi-gram preparation of both final targets and advanced intermediates for SAR expansion.

Discovery and structure-activity relationships of novel selective norepinephrine and dual serotonin/norepinephrine reuptake inhibitors.

Novel arylthiomethyl morpholines are potent selective norepinephrine reuptake inhibitors (NERIs) and dual serotonin/norepinephrine reuptake inhibitors (SRI/NERIs). The target compounds were prepared using a stereochemically versatile synthesis featuring an aldol condensation as the key step. One enantiomer of the 2-methoxy-substituted analogue was found to be a potent and selective norepinephrine reuptake inhibitor, whereas the opposite enantiomer was a potent dual serotonin/norepinephrine reuptake inhibitor.

Structure-based design of agrochemicals.

This review covers recent advances in the structure-based design of agrochemicals. The three main sectors of agrochemistry, i.e. herbicides, insecticides, and fungicides are covered. The literature in this field to the present date is reviewed and 88 references are cited.