Paroxysmal atrial fibrillation and hemochromatosis: a narrative review.

Paroxysmal atrial fibrillation (PAF) and hemochromatosis have a complex relationship. This review explores its mechanisms, prevalence, correlations, and clinical manifestations. Hereditary hemochromatosis (HH) involves iron overload due to HFE protein mutations, while atrial fibrillation (AF) is characterized by irregular heart rhythms. Iron overload in hemochromatosis can promote cardiac arrhythmias. AF is prevalent in developed countries and may be linked to cryptogenic strokes. Genetic variations and demographic factors influence the occurrence of both conditions. HH affects multiple organ systems, including the heart, while AF causes palpitations and reduced exercise tolerance. Diagnosis involves iron markers, genotypic testing, and electrocardiogram (ECG) findings. Treatment strategies focus on reducing iron levels in hemochromatosis and managing AF through antithrombotic therapy and rhythm control. Untreated hemochromatosis carries a higher risk of complications, and PAF is associated with increased cardiovascular-related mortality. For better understanding of the mechanisms and to improve management, additional studies are required. Tailored approaches and combined treatments may enhance patient outcomes.

Visible light-driven photocatalytic bacterial inactivation on PPE, supported by the DFT and bactericidal study.

A novel ZnO-MoO3-ZnMoO3@graphene GZM composite catalyst prepared by microwave hydrothermal process for personal protective equipment textiles (PPE) is presented in this study. The results indicated that the GZM with defect vacancy sites of two types as observed by EPR showed significantly superior inactivation of the E. coli bacteria compared to GZM without the lower defect vacancy sites and concomitant lower electron densities. Photocatalytic activated oxidation by the GZM composites coatings was observed to proceed in acceptable times as well as the bacterial inactivation (log bact. C/Co > 107 within 3 h). Defect sites in the GZM seem to be important leading to the bacterial inactivation process. DFT calculations on the GZM with and without catalyst defect sites were carried out. The electron densities were estimated by the Fourier mapping. The results found in this study showed the potential of GZM-PPE for practical applications.

Active Dry Yeast and Thiamine in Synergistic Mode Can Mitigate Adverse Effects of In Vitro Ruminal Acidosis Model of Goats.

Ruminal acidosis is a type of metabolic disorder of high-yielding ruminants which is associated with the consumption of a high-grain diet. It not only harms the productive efficiency, health and wellbeing of the animals but also has detrimental effects on the economy of the farmers. Various strategies have been adapted to control ruminal acidosis. However, none of them have produced the desired results. This research was carried out to investigate the potential of active dry yeast (ADY) and thiamine in a synergistic mode to mitigate in vitro-induced ruminal acidosis. The purpose of this study was to determine how active dry yeast alone and in combination with thiamine affected the ruminal pH, lactate, volatile fatty acids, lipopolysaccharides (LPS) and microbial community in in vitro-induced ruminal acidosis. The experiment comprises three treatment groups, (1) SARA/control, (2) ADY and (3) ADYT (ADY + thiamine). In vitro batch fermentation was conducted for 24 h. The results indicated that ruminal induced successfully and both additives improved the final pH (p < 0.01) and decreased the LPS and lactate (p < 0.01) level as compared to the SARA group. However, the ADYT group decreased the level of lactate below 0.5 mmol/L. Concomitant to fermentation indicators, both the treatment groups decreased (p < 0.05) the abundance of lactate-producing bacteria while enhancing (p < 0.01) the abundance of lactate-utilizing bacteria. However, ADYT also increased (p < 0.05) the abundance of protozoa compared to the SARA and ADY group. Therefore, it can be concluded that ADY and thiamine in synergistic mode could be a better strategy in combating the adverse effects of subacute ruminal acidosis.

Shedding Light on the Synthesis, Crystal Structure, Characterization, and Computational Study of Optoelectronic Properties and Bioactivity of Imine derivatives.

Two imine compounds named as (E)-2-(((3,4-dichlorophenyl)imino)methyl)phenol (DC2H) and (E)-4-(((2,4-dimethylphenyl)imino)methyl)phenol (DM4H) are synthesized, and their crystal structures are verified using the single-crystal X-ray diffraction (XRD) technique. The crystal structures of the compounds are compared with the closely related crystal structures using the Cambridge Structural Database (CSD). The crystal packing in terms of intermolecular interactions is fully explored by Hirshfeld surface analysis. Void analysis is carried out for both compounds to check the strength of the crystal packing. Furthermore, a state-of-the-art dual computational technique consisting of quantum chemical and molecular docking methods is used to shed light on the molecular structure, optoelectronic properties, and bioactivity of indigenously synthesized compounds. The optimized molecular geometries are compared with their counterpart experimental values. Based on previous reports of biofunctions of the indigenously synthesized imine derivatives, they are explored for their potential inhibition properties against two very crucial proteins (main protease (Mpro) and nonstructural protein 9 (NSP9)) of SARS-CoV-2. The calculated interaction energy values of DC2H and DM4H with Mpro are found to be -6.3 and -6.6 kcal/mol, respectively, and for NSP9, the calculated interaction energy value is found to be -6.5 kcal/mol. We believe that the current combined study through experiments and computational techniques will not only pique the interest of the broad scientific community but also evoke interest in their further in vitro and in vivo investigations.

LIFR inhibition enhances the therapeutic efficacy of HDAC inhibitors in triple negative breast cancer.

Histone deacetylase inhibitors (HDACi) are identified as novel therapeutic agents, however, recent clinical studies suggested that they are marginally effective in treating triple negative breast cancer (TNBC). Here, we show that first-in-class Leukemia Inhibitory Factor Receptor (LIFRα) inhibitor EC359 could enhance the therapeutic efficacy of HDACi against TNBC. We observed that both targeted knockdown of LIFR with CRISPR or treatment with EC359 enhanced the potency of four different HDACi in reducing cell viability, cell survival, and enhanced apoptosis compared to monotherapy in TNBC cells. RNA-seq studies demonstrated oncogenic/survival signaling pathways activated by HDACi were attenuated by the EC359 + HDACi therapy. Importantly, combination therapy potently inhibited the growth of TNBC patient derived explants, cell derived xenografts and patient-derived xenografts in vivo. Collectively, our results suggest that targeted inhibition of LIFR can enhance the therapeutic efficacy of HDACi in TNBC.

The Effect of Replacing Wildrye Hay with Mulberry Leaves on the Growth Performance, Blood Metabolites, and Carcass Characteristics of Sheep.

The objective of this study was to evaluate the effects of partially substituting for conventional forage, Chinese wildrye (CW), with mulberry leaves (ML) on the growth, digestion, ruminal fermentation, blood metabolites, and meat quality of sheep in a 65-day feedlot study. Thirty-two four-month-old male small-tailed Han sheep (25.15 ± 1.03 kg) were randomly assigned to one of four treatments. The dietary treatments consisted of four proportions of ML (0, 8, 24, and 32%) as a substitute for CW (designated as ML0, ML8, ML24, and ML32, respectively). Rumen digesta and blood samples were collected at day 63 of the trial. Carcass traits were assessed after slaughter at the end of performance period. The results from this study revealed no differences in average daily bodyweight gain (ADG), feed conversion ratio (FCR), and final body weight (FBW) among treatments. The apparent digestibility of dry matter (DM), organic matter (OM), and acid detergent fiber (ADF) was higher in the sheep fed with ML than in those fed CW. The ML24 treatment had a higher digestibility of crude protein (CP) and ether extract (EE). There were no differences (p = 0.13) in ruminal pH values among the treatments. However, there was more microbial protein (p < 0.01) in ML24 and ML32 treatments than the ML0 treatment. Ruminal concentrations of acetate and butyrate were significantly different among treatments, although no difference in concentrations of total volatile fatty acid were found. Additionally, no differences were detected for serum parameters except blood urea nitrogen (BUN). No differences were observed for carcass weight (p = 0.62), dressing percentage (p = 0.31) or longissimus dorsi muscle (LM) area (p = 0.94) among treatments. However, intramuscular fat was higher in the ML24 treatment than in the ML0 treatment. (p < 0.01). There were higher pH values of the 24-h longissimus dorsi in the ML24 treatment than in the ML0 treatment. In addition, the saturated fatty acid (SFA) content was lower (p < 0.01) and the monounsaturated fatty acid (MUFA) content higher (p < 0.01) in the ML24 treatment than in the ML0 treatment. In conclusion, the partially substitution of mulberry leaves for Chinese wildrye in the diet of sheep had a beneficial influence on the growth performance, blood metabolites and carcass characteristics. The inclusion of 24% (air dry basis) mulberry leaf hay in the ration of sheep is recommended based on these findings.

ß-Sitosterol Attenuates High Grain Diet-Induced Inflammatory Stress and Modifies Rumen Fermentation and Microbiota in Sheep.

ß-sitosterol (BSS) is a plant-derived natural bioactive compound, its cellular mechanism of anti-inflammatory activity has been proven recently. Little information is available regarding the application of BSS on ruminants under high grain diet. The objective of this study was to evaluate the effects of dietary BSS supplementation on inflammatory response, ruminal fermentation characteristics and the composition of the ruminal bacterial community under high grain diet. Eight rumen-cannulated Hu sheep (59.7 ± 4.8 kg of initial body weight) were randomly assigned into a replicated 4 × 4 Latin square design trial. Sheep were fed a high grain diet (non-fiber carbohydrate: neutral detergent fiber = 2.03) supplemented either with 0.25 (LBS), 0.5 (MBS), 1.0 (HBS) or without (CON) g BSS /kg dry matter diet. On day 21 of each period, rumen content samples were obtained at 6 h postfeeding, and blood samples were obtained before morning feeding. The data showed that compared with control group, Dietary BSS supplementation decreased serum concentrations of tumor necrosis factor, interleukin (IL)-6, and IL-1ß. The ruminal pH and acetate concentration for BSS treatment were improved, while concentration of propionate, butyrate and lactate was decreased. The result of Illumina MiSeq sequencing of 16S rRNA gene revealed that BSS addition can increase the proportion of Prevotella_1, Rikenellaceae_RC9_gut_group, Prevotella_7, and Selenomonas_1, and decrease the proportion of Lachnospiraceae_NK3A20_group. These results indicated that BSS attenuates high grain diet-induced inflammatory response and modifies ruminal fermentation. In addition, the BSS dietary supplementation at the level of 0.5 g/kg is recommended in sheep.

Oxygen-Cluster-Modified Anatase with Graphene Leads to Efficient and Recyclable Photo-Catalytic Conversion of CO2 to CH4 Supported by the Positron Annihilation Study.

Anatase TiO2 hollow nanoboxes were synthesized and combined with the graphene oxide to get nanocomposite of TiO2/rGO (TG). Graphene oxide was used to modify the Oxygen-Clusters and bulk to surface defects. Anatase and TG composite were characterized with the positron annihilation, XPS, EPR, EIS and photocurrent response analysis. The relative affects of defects on the photocatalytic reduction (CO2 to CH4) were studied. The TG composites showed highest photo-catalytic activity after GO coupling (49 µmol g-1 h-1), 28.6 times higher photocurrent yields much higher quantum efficiency (3.17%@400 nm) when compared to the TiO2 nanoboxes. The mechanism of enhanced photo-catalytic CO2 conversion to CH4 elucidated through electrochemical and photo-catalytic experiments with traceable isotope containing carbon dioxide (13CO2). For the first time we discovered that diminishing the comparative concentration ratio of anatase from the bulk to surface defects could significantly increase the conversion of CO2 to CH4.

Enhanced photocatalytic H2 production under visible light on composite photocatalyst (CdS/NiSe nanorods) synthesized in aqueous solution.

Cocatalysts play a critical role in the activity and stability of photocatalytic systems. Currently, efficient cocatalysts mainly comprise of expensive noble metals. Herein we report a composite photocatalyst consisting of CdS nanorods (NRs) and noble-metal-free cocatalyst NiSe, which efficiently enhances the hydrogen production activity of CdS NRs under visible light. NiSe was synthesized through a facile aqueous solution method and CdS/NiSe NRs composites were prepared by in situ deposition of NiSe on CdS NRs. This provides increased contact between cocatalyst and photosensitizer leading to enhanced electron transfer at the interface of NiSe and CdS. The current photocatalytic system gave the highest hydrogen evolution rate of 340 µmol h-1 under optimal conditions. The enhanced stability of the system was observed for 30 h of irradiation resulting in 14 mmol of hydrogen evolution. The highest AQY of 12% was observed using the 420 nm monochromatic light. In addition, CdS/NiSe NRs showed significant higher H2 evolution rate than that of 1.0 wt% loaded CdS/Pt NRs proving NiSe as highly efficient cocatalyst. Photoluminescence spectra and the photocurrent response were used to confirm the efficient charge transfer at the interface of NiSe and CdS nanorods. The work presented here demonstrates the successful use of an inexpensive, non-noble-metal cocatalyst for enhanced photocatalytic hydrogen production.

Esters of levonorgestrel and etonogestrel intended as single, subcutaneous-injection, long-lasting contraceptives.

An effort with the goal of discovering single-dose, long-lasting (>6 months) injectable contraceptives began using levonorgestrel (LNG)-17-ß esters linked to a sulfonamide function purposed as human carbonic anhydrase II (hCA 2) ligands. One single analog from this first series showed noticeably superior anti-ovulatory activity in murine models, and a subsequent structure-activity relationship (SAR, the relationship between a compound's molecular structure and its biological activity) study based on this compound identified a LNG-phenoxyacetic acid ester analog exhibiting longer anti-ovulatory properties using the murine model at 2 and 4 mg dose than medroxyprogesterone acetate (MPA). The same ester function linked to etonogestrel (ENG) furnished a compound which inhibited ovulation at 2 mg for 60 days, the longest duration of all compounds tested at these doses. By comparison, MPA at the same dose inhibited ovulation for 32 days.

Jugular arginine infusion relieves lipopolysaccharide-triggered inflammatory stress and improves immunity status of lactating dairy cows.

The objective of this study was to evaluate the effects of jugular l-Arg infusion on performance and immune function during lipopolysaccharide (LPS)-induced inflammation of lactating dairy cows. Eight Holstein cows (multiparous, 608.8 ± 31.5 kg) at mid-lactation were randomly assigned to 5-d jugular infusions of control (saline), Arg (3 g/h), LPS (0.033 µg/kg per h), and LPS + Arg (0.033 µg/kg per h of LPS and 3 g/h of Arg) in a replicated 4 × 4 Latin square design with 4 infusion periods separated by 10-d noninfusion periods. Jugular solutions of saline, Arg, LPS, and LPS + Arg were continuously infused using peristaltic pumps for approximately 6 h/d during infusion periods. Milk yield was measured on each day of the infusion period. Milk samples were obtained on the last 2 d of each infusion period, and blood samples were obtained on the last day of each infusion period before infusion (0 h) and at 3 and 6 h. We found that the jugular LPS infusion significantly increased serum concentrations of IL-1ß, IL-6, tumor necrosis factor, inducible nitric oxide synthase, and lipopolysaccharide binding protein, whereas Arg attenuated the increase in IL-6 and inducible nitric oxide synthase levels and tended to decrease the lipopolysaccharide binding protein level. Arginine alleviated the decrease in dry matter intake and milk fat yield and the increase of somatic cell count induced by LPS. Total casein in milk was decreased during the LPS-induced inflammation period, and jugular Arg infusion significantly increased the content of total casein. In contrast, lactalbumin in milk increased during the LPS-induced inflammation period, whereas jugular Arg infusion significantly decreased the content of lactalbumin. The concentrations of plasma Gly, Thr, Ile, Leu, Arg, Phe, and total free AA were significantly decreased by LPS treatment, but Arg attenuated this tendency. These results indicated that jugular Arg infusion (18 g/d) has protective effects on relieving inflammatory stress and improving immunity status triggered by LPS. In conclusion, Arg could attenuate inflammatory stress and improve milk performance of lactating dairy cows. This protective effect may be due to the ability of Arg to suppress LPS effects and improve immunity status.

A prodrug design for improved oral absorption and reduced hepatic interaction.

A series of estradiol-17-ß esters of N-(p-sulfomylbenzamide)-amino acids were prepared and evaluated for systemic and hepatic estrogenic activity after oral administration in ovariectomized rats. The alkyl substitution at nitrogen of amino acids such as proline or N-methyl-alanine produced compounds that exhibit potent oral activity. The proline analog (EC508) was further evaluated along with 17ß-estradiol (E2) and ethinyl-estradiol (EE) and compared their effects on the uterus, angiotensin and HDL-cholesterol after oral administration to ovariectomized female rats. Orally administered EC508 produced systemic estrogenic activity 10 times greater than EE and a 100 times higher activity than E2 with no influence on levels of angiotensin and HDL-cholesterol, whereas EE and E2 reduced the HDL-cholesterol and increased the angiotensine plasma levels. EC508 might offer significant advantages in indications like fertility control and HRT based on its high oral bioavailability and lack of hepatic estrogenicity.

Rational design of a tripartite-layered TiO2 photoelectrode: a candidate for enhanced power conversion efficiency in dye sensitized solar cells.

A tri-layered photoelectrode for dye-sensitized solar cells (DSSCs) is assembled using single crystal hollow TiO2 nanoparticles (HTNPs), sub-micro hollow TiO2 mesospheres (SHTMSs) and hierarchical TiO2 microspheres (HTMSs). The bottom layer composed of single crystal hollow TiO2 nanoparticles serves to absorb dye molecules, harvest light due to its hollow structure and keep a better mechanical contact with FTO conducting glass; the middle layer consisting of sub-micro hollow mesospheres works as a multifunctional layer due to its high dye adsorption ability, strong light trapping and scattering ability and slow recombination rates; and the top layer consisting of hierarchical microspheres enhances light scattering. The DSSCs made of photoanodes with a tripartite-layer structure (Film 4) show a superior photoconversion efficiency (PCE) of 9.24%, which is 7.4% higher than a single layered photoanode composed of HTNPs (Film 1: 8.90%), 4.6% higher than a double layer-based electrode consisting of HTNPs and SHTMSs (Film 2: 9.03%) and 2.6% higher than a double layer-based electrode made of HTNPs and HTMSs (Film 3: 9.11%). The significant improvements in the PCE for tri-layered TiO2 photoanodes are mainly because of the combined effects of their higher light scattering ability, long electron lifetime, fast electron transport rate, efficient charge collection and a considerable surface area with high dye-loading capability. This study confirms that the facile tri-layered photoanode is an interesting structure for high-efficiency DSSCs.

Thermodynamic Meerwein-Ponndorf-Verley reduction in the diastereoselective synthesis of 17α-estradiol.

The synthesis of 17α-hydroxy steroids generally requires multiple synthetic manipulations. The synthesis of 17α-estradiol is no exception, as this process involves the protection and release of the 3-hydroxy functional group. The diastereoselective reduction of the 17-keto-steroid can be utilized to prepare 17α-hydroxy-steroids. Here, 17α-estradiol was synthesized from commercially available estrone under thermodynamic Meerwein-Ponndorf-Verley (MPV) conditions in a single step, followed by simple chromatographic separation over silica gel. The remaining mixture of unreacted estrone and estradiols was easily recycled through Oppenauer oxidation to estrone, with an overall yield of 68% 17α-estradiol.

Tennis elbow: role of local steroid injection.

BACKGROUND: Tennis elbow is a condition, characterised by pain and tenderness over the lateral epicondyle of the humerus, and pain on resisted dorsiflexion of the wrist, middle finger, or both. The aim of this randomised controlled trial was to investigate the short term efficacy of local steroid injection compared with oral and topical NSAIDs. METHODS: Sixty patients (45 male and 15 female) were included in the study. The mean age was 42 years for men and 40 years for women. They were placed in group A and B (30 cases each). Group A received local steroid injection (triamcinolone 20 mg mixed with lignocaine 2% 1 cc) and topical NSAID cream application (diclofenac diethylammonium) twice a day, tab. diclofenac sodium 50 mg twice a day for 3 weeks. Group B received tab diclofenac 50 mg twice a day and, topical NSAID cream application twice a day for 3 weeks. Assessment of patients was made 3 times; first at the start of the study, 2nd time after 6 weeks, and 3rd time after 12 weeks. A blinded assessor rated the elbow complaints of the patients at resisted dorsiflexion of wrist using VAS (0 = no severity, 1-3 mild, 4-6 moderate, 7-9 sever, 10 = maximum severity). RESULTS: At six weeks, 22 (73.33%) patient in group A had no pain as compared to 7 (23.33%) patients in group B who were pain free (p < 0.0001, chi2 = 38.75). At 12 weeks 27 (90%) patients in group A were pain free compared to group B in which 7 (23.33%) patients were pain free (p < 0.0001, chi2 = 27.56). CONCLUSION: In patients with tennis elbow, the use of local steroid injection in combination with topical and oral NSAIDs is superior to the use of combination of topical and oral NSAIDs. Better results with combination therapy using local steroid injection may be limited to the short term.

Discovery and characterization of triaminotriazine aniline amides as highly selective p38 kinase inhibitors.

The p38 mitogen-activated protein (MAP) kinases are a family of serine/threonine protein kinases that play important roles in cellular responses to inflammation and external stress. Inhibitors of the p38 MAP kinase have shown promise for potential treatment of inflammatory disorders such as rheumatoid arthritis, acute coronary syndrome, psoriasis, and Crohn's disease. We identified a novel class of p38 inhibitors via high-throughput screening. PS200981 [3-(4-(1,4-diazepan-1-yl)-6-(((1S,2R,5S)-6,6-dimethylbicyclo[3.1.1]heptan-2-yl)methylamino)-1,3,5-triazin-2-ylamino)-4-methylbenzamide], a representative compound identified from screening a collection of combinatorial libraries, amounting to 2.1 million compounds, inhibits p38alpha kinase and the lipopolysaccharide (LPS)-induced increase in tumor necrosis factor (TNF) alpha levels in cell media of human monocytes with IC50 values of 1 microM. The screening data revealed a preferred synthon, 3-amino-4-methyl benzamide, which is critical for the activity against p38. This synthon appeared almost exclusively in screening hits including PS200981, and slight variations of this synthon including 3-amino benzamide and 2-amino-4-methyl benzamide also contained in the library were inactive. PS200981 is equally potent against the alpha and beta forms of p38 but did not inhibit p38 gamma and is >25-fold selective versus a panel of other kinases. PS200981 inhibited the LPS-induced increase in TNFalpha levels when administered at 30 mg/kg to mice. Selectivity and in vivo activity of this class of p38 inhibitors was further demonstrated by PS166276 [(R)-3-(4-(isobutyl(methyl)-amino)-6-(pyrrolidin-3-ylamino)-1,3,5-triazin-2-ylamino)-4-methylbenzamide], a highly structurally related but more potent and less cytotoxic inhibitor, in several intracellular signaling assays, and in LPS-challenged mice. Overall, this novel class of p38 inhibitors is potent, active in vitro and in vivo, and is highly selective.

5-Cyanopyrimidine derivatives as a novel class of potent, selective, and orally active inhibitors of p38alpha MAP kinase.

A novel class of 5-cyanopyrimidine-based inhibitors of p38alpha MAP kinase has been investigated. Analogues optimized through SAR iterations display low nanomolar enzymatic and cellular activity. The in vivo efficacy of this class of p38 inhibitors was demonstrated by 3a and 3b (>50% reduction in TNF levels when orally dosed at 5 mg/kg, 5 h prior to LPS administration in an acute murine model of inflammation). For 3a and 3b, the previously identified N-methoxybenzamide moiety (1) was replaced with N-(isoxazol-3-yl)benzamide, thereby providing increased metabolic stability. Cyanopyrimidine 3a demonstrated 100% oral bioavailability in mouse. High p38 kinase selectivity versus over 20 kinases was observed for analogue 3b. Direct hydrogen bonding of the cyano nitrogen of the 5-cyanopyrimidine core to the backbone NH of Met109 was confirmed by X-ray crystallographic analysis of 3a bound to p38alpha.

The discovery of orally active triaminotriazine aniline amides as inhibitors of p38 MAP kinase.

A new structural class of triaminotriazine aniline amides possessing potent p38 enzyme activity has been discovered. The initial hit (compound 1a) was identified through screening the Pharmacopeia ECLiPS compound collection. SAR modification led to the identification of a short acting triaminotriazine aniline methoxyamide (compound 1m) possessing in vitro and in vivo oral activity in animal models of acute and chronic inflammatory disease. An X-ray crystal structure of compound 1m in this class, cocrystallized with unactivated p38 alpha protein, indicates that these compounds bind to the ATP binding pocket and possess key H-bonding interactions within a deeper cleft. Hydrogen bonding between one of the triazine nitrogens and the backbone NH of the Met109 residue occurs through a water molecule. The methoxyamide NH and carbonyl oxygen are within H-bonding distance of Glu71 and Asp168.

Asymmetric Synthesis of 2,3-Dihydrofurans by Reaction of Rhodium-Stabilized Vinylcarbenoids with Vinyl Ethers.

Rhodium(II) octanoate catalyzed decomposition of 2-diazo-3-siloxybutenoates, containing (R)-pantolactone as a chiral auxiliary, in the presence of vinyl ethers results in the diastereoselective synthesis of cyclopropanes with high asymmetric induction. Treatment of the cyclopropanes with tetrabutylammonium fluoride results in desilylation and ring expansion of the resulting acylcyclopropanes to 2,3-dihydrofurans with retention of stereochemistry.