A metal-free strategy to construct fluoroalkyl-olefin linkages using fluoroalkanes.

We present a metal-free strategy to access fluoroalkyl-olefin linkages from fluoroalkane precursors and vinyl-pinacol boronic ester (BPin) reagents. This reaction sequence is templated by the boron reagent, which induces C-C bond formation upon oxidation. We developed this strategy into a one-pot synthetic protocol using RCF2H precursors directly with vinyl-BPin reagents in the presence of a Brønsted base, which tolerated oxygen- and nitrogen-containing heterocycles, and aryl halogens. We also found that HCF3 (HCF-23; a byproduct of the Teflon industry) and CH2F2 (HCF-32; a low-cost refrigerant) are amenable to this protocol, representing distinct strategies to generate RCF2H and RCF3 molecules. Finally, we demonstrate that the vinyldifluoromethylene products can be readily derivatized, representing an avenue for late-stage modification after installing the fluoroalkyl unit.

Understanding Reactive Sulfur Species through P/S Synergy.

We investigated the differential oxidative and nucleophilic chemistry of reactive sulfur and oxygen anions (SSNO-, SNO-, NO2-, S42-, and HS-) using the simple reducing electrophile PPh2Cl. In the case of SSNO- reacting with PPh2Cl, a complex mixture of mono and diphosphorus products is formed exclusively in the P(V) oxidation state. We found that the phosphine stoichiometry dictates selectivity for oxidation to P=S/P=O products or transformation to P2 species. Interestingly, only chalcogen atoms are incorporated into the phosphorus products and, instead, nitrogen is released in the form of NO gas. Finally, we demonstrate that more reducing anions (S42- and HS-) also react with PPh2Cl with P=S bond formation as a key reaction driving force.

Nucleophilic strategies to construct -CF2- linkages using borazine-CF2Ar reagents.

Using a Lewis acid-quenched CF2Ph- reagent, we show C-C bond formation through nucleophilic addition reactions to prepare molecules containing internal -CF2- linkages. We demonstrate C(sp2)-C(sp3) coupling using both SNAr reactions and Pd-catalysis. Finally, C(sp3)-C(sp3) bonds are forged using operationally simple SN2 reactions that tolerate medicinally-relevant motifs.

Defluorinative Functionalization of Pd(II) Fluoroalkyl Complexes.

When subjected to arylboranes, anionic trifluoromethyl and difluorobenzyl palladium(II) complexes undergo fluoride abstraction followed by 1,1-migratory insertion. The resulting intermediate fluoroalkyl species can be induced to undergo a subsequent transmetalation and reductive elimination from either an in situ formed fluoroboronate (FB(Ar3)-) or an exogenous boronic acid/ester (ArB(OR)2) and nucleophilic activator, representing a net defluorinative arylation reaction. The latter method enabled a structurally diverse substrate scope to be prepared from either an isolated palladium-CF3 complex, or from Pd(PPh3)4 and other commercially available reagents.

Epidemiology and Diagnosis of Gastroparesis in the United States: A Population-based Study.

GOALS: We aimed to establish the epidemiological characteristics and documentation of diagnostic workup for gastroparesis (GP). BACKGROUND: No study has used a national database to evaluate the prevalence, demographics, and associated comorbid conditions of GP, and document rates of proper diagnosis. MATERIALS AND METHODS: This was a cross-sectional population-based study using the Explorys Platform to determine the prevalence of GP in a large and diverse population highly representative of the US population and to examine the diagnostic approach of GP. Data collected were individual characteristics from electronic medical records (EMRs) included age, ethnicity/race, sex, diagnostic report for esophagogastroduodenoscopy (EGD) and gastric emptying study (GES). RESULTS: A total of 43,827,910 medical records were surveyed (1999 to 2014), of which 69,950 had a diagnosis of GP, yielding an overall prevalence of 0.16%. We identified 249,930 EMRs with type 1 diabetes mellitus (T1DM), and 2,940,280 EMR's with type 2 diabetes mellitus (T2DM), of which 11,470 (4.59%) and 38,670 (1.31%) EMR's had concurrent GP, respectively. The remainder 19,810 EMRs with a diagnosis of GP were classified as having idiopathic GP. In all three subgroups, women and Caucasians had the highest prevalence of GP. The diagnosis of GP was confirmed by both GES and EGD in 9,950 of patients (14.22%). For patients with T1DM, T2DM, or idiopathic GP, GP was confirmed by both diagnostic tests in 16.8%, 14.0%, and 13.2%, respectively. CONCLUSIONS: Our estimated rates of prevalence of GP in T1DM and T2DM indicate that GP is not a common clinical complication in these populations. Majority of EMRs that indicated a diagnosis of GP did not include any documentation of definitive diagnostic testing (EGD and/or GES).

The Difluoromethyl Group as a Masked Nucleophile: A Lewis Acid/Base Approach.

The difluoromethyl group (R-CF2H) imparts desirable pharmacokinetic properties to drug molecules and is commonly targeted as a terminal functional group that is not amenable to further modification. Deprotonation of widely available Ar-CF2H starting materials to expose nucleophilic Ar-CF2- synthons represents an unexplored, yet promising route to construct benzylic Ar-CF2-R linkages. Here we show that the combination of a Brønsted superbase with a weak Lewis acid enables deprotonation of Ar-CF2H groups and capture of reactive Ar-CF2- fragments. This route provides access to isolable and reactive Ar-CF2- synthons that react with a broad array of electrophiles at room temperature. The methodology is highly general in both electrophile and difluoromethyl (hetero)arene and can be applied directly to the synthesis of benzylic difluoromethylene (Ar-CF2-R) linkages, which are useful lipophilic and metabolically resistant replacements for benzylic linkages in medicinal chemistry.

Borazine-CF3- Adducts for Rapid, Room Temperature, and Broad Scope Trifluoromethylation.

A fluoroform-derived borazine CF3- transfer reagent is used to effect rapid nucleophilic reactions in the absence of additives, within minutes at 25 °C. Inorganic electrophiles spanning seven groups of the periodic table can be trifluoromethylated in high yield, including transition metals used for catalytic trifluoromethylation. Organic electrophiles included (hetero)arenes, enabling C-H and C-X trifluoromethylation reactions. Mechanistic analysis supports a dissociative mechanism for CF3- transfer, and cation modification afforded a reagent with enhanced stability.

A randomized, controlled comparison of ibuprofen at the maximal over-the-counter dose compared with prescription-dose celecoxib on upper gastrointestinal mucosal injury.

BACKGROUND & AIMS: Ibuprofen is a well-tolerated nonsteroidal anti-inflammatory drug (NSAID), particularly at over-the-counter (OTC) doses. Cyclooxygenase 2 (COX-2)-selective inhibitors cause less ulceration than prescription-dose nonselective NSAIDs. We compared endoscopic injury related to nonprescription ibuprofen doses with celecoxib, also comparing prescription doses of naproxen with placebo as a positive control. METHODS: The study was a randomized, placebo-controlled, double blind, double-dummy endoscopic evaluation with concealed allocation. A 2-way crossover with a 4-5-week washout period was used. Participants were healthy adults with normal baseline findings from endoscopy. Ninety-five subjects were randomly assigned, and 79 subjects completed both study phases. Age distribution was reflective of the target population of the OTC agent. Twenty percent were infected with Helicobacter pylori, and 79% and 67% had a current or past medical problem, respectively. Qualifying subjects, stratified by the presence or absence of H. pylori infection (n = 20), were randomly assigned to 1 of the 4 sequences (phase I/II) as follows: ibuprofen/celecoxib; celecoxib/ibuprofen, naproxen/placebo, or placebo/naproxen. Primary end points were the frequency of endoscopic ulcers and erosions in the groups administered: (1) celecoxib vs. ibuprofen and (2) naproxen vs. placebo. RESULTS: In celecoxib-treated subjects, 2.6% developed ulcers compared with 17.9% of those treated with ibuprofen (P = 0.056). Naproxen treatment was associated with a significantly greater ulceration rate compared with placebo. CONCLUSIONS: Short-term use of the nonselective COX inhibitors ibuprofen and naproxen is associated with a greater risk for endoscopic mucosal injury compared with the COX-2-selective inhibitor celecoxib or placebo. A prospective analysis appropriately powered to address the incidence of clinically significant gastroduodenal ulceration associated with the short-term use of these agents would be required to further define the clinical relevance of these findings.