The plant growth-promoting effect of the nitrogen-fixing endophyte Pseudomonas stutzeri A15.

The use of plant growth-promoting rhizobacteria as a sustainable alternative for chemical nitrogen fertilizers has been explored for many economically important crops. For one such strain isolated from rice rhizosphere and endosphere, nitrogen-fixing Pseudomonas stutzeri A15, unequivocal evidence of the plant growth-promoting effect and the potential contribution of biological nitrogen fixation (BNF) is still lacking. In this study, we investigated the effect of P. stutzeri A15 inoculation on the growth of rice seedlings in greenhouse conditions. P. stutzeri A15 induced significant growth promotion compared to uninoculated rice seedlings. Furthermore, inoculation with strain A15 performed significantly better than chemical nitrogen fertilization, clearly pointing to the potential of this bacterium as biofertilizer. To assess the contribution of BNF to the plant growth-promoting effect, rice seedlings were also inoculated with a nitrogen fixation-deficient mutant. Our results suggest that BNF (at best) only partially contributes to the stimulation of plant growth.

Aryne cycloaddition reactions of benzodioxasilines as aryne precursors generated by catalytic reductive ortho-C-H silylation of phenols with traceless acetal directing groups.

Diversely substituted arylsilyl triflates, as aryne precursors for aryne cycloaddition reactions, were accessed from benzodioxasilines. Catalytic reductive C-H ortho-silylation of phenols with traceless acetal directing groups was exploited to prepare benzodioxasilines. Sequential addition of MeLi and then trifluoromethanesulfonic anhydride to benzodioxasilines provided arylsilyl triflates in a single pot. Notably, this approach was successfully utilized to prepare sterically hindered 1,2,3-trisubstituted arylsilyl triflates, which ultimately underwent fluoride-mediated aryne cycloaddition.

Catalytic Net Oxidative C-C Activation and Silylation of Cyclopropanols with a Traceless Acetal Directing Group.

Redox-neutral carbon-carbon (C-C) bond activation and functionalization strategies of cyclopropanols that give metallo homoenolate have offered merits to construct a range of useful ß-functionalized ketones in an inverse-polarity fashion. Discovery and identification of oxidative C-C activation reactions of cyclopropanols that generate metallo enolate-homoenolate would provide an opportunity to afford α,ß-difunctionalized ketones. We report catalytic, net oxidative C-C activation, and silylation of cyclopropanols with traceless acetal directing groups under consecutive Ir and Rh catalysis in regio-, stereo-, and chemo-selective fashion. In detail, Ir-catalyzed hydrosilylation of cyclopropyl acetates provides the acetal directing group in quantitative yield. Rh-catalyzed proximal C-C silylation of the resulting cyclopropyl silyl acetal produces the metallo enolate-homoenolate equivalent, dioxasilepine, which uniquely holds an interconnected ß-silyl moiety and Z-vinyl acetal. Upon sequential treatment of a silaphile that removes the acetal directing group and electrophile, the seven-membered silicon-containing heterocycle, serving as the ketone α,ß-dianion equivalent, delivers α,ß-difunctionalized ketones. Scope of the hitherto unexplored reactivity of cyclopropanols toward net oxidative C-C silylation and the versatility of the resulting dioxasilepines were demonstrated. These include late-stage, net oxidative C-C silylation of biologically relevant molecules and facile production of a range of α,ß-difunctionalized ketones. Preliminary mechanistic studies suggest that the C-C activation harnessing the electron-rich Wilkinson-type catalyst is likely the turnover-determining step and a Rh-π interaction is the key to the efficient metal insertion to the proximal C-C bond in cyclopropanols.

Salvage of Chronic Therapy-Resistant Bilateral Charcot Foot Osteoarthropathy with Signs of Osteomyelitis.

Charcot arthropathy is an insidious condition affecting the lower limbs of diabetic patients. It is a complication of diabetic neuropathy resulting from subsequent Wallerian degeneration of the nerves. This complication may eventually lead to limb amputation and a poor patient prognosis if not diagnosed and treated successfully. Herein, we report the case of a 73-year-old female who presented with rapidly progressive bilateral Charcot foot over a 5-week period, necessitating an exostectomy on the mid foot, specifically on the cuboid bone and the navicular cuneiform joint. Her presentation with rapidly progressing foot ulcers on the plantar aspect prompted initial treatment based on osteomyelitis. The report will therefore serve as a useful guide on how to properly treat Charcot foot, which may present in an atypical manner.

Presentation and Treatment of cholinergic Crisis in the setting of Carbamate poisoning.

The case details the acute onset of muscarinic poisoning with associated symptoms and long-term complications, as a new readily available suicide tool that clinicians should be keen to, combined with the appropriate treatment so lifesaving therapy may be urgently administered along with future mental health therapy.

Lewis Base Activation of Silyl Acetals: Iridium-Catalyzed Reductive Horner-Wadsworth-Emmons Olefination.

A Lewis base promoted deprotonative pronucleophile addition to silyl acetals has been developed and applied to the iridium-catalyzed reductive Horner-Wadsworth-Emmons (HWE) olefination of esters and the chemoselective reduction of the resulting enoates. Lewis base activation of silyl acetals generates putative pentacoordinate silicate acetals, which fragment into aldehydes, silanes, and alkoxides in situ. Subsequent deprotonative metalation of phosphonate esters followed by HWE with aldehydes furnishes enoates. This operationally convenient, mechanistically unique protocol converts the traditionally challenging aryl, alkenyl, and alkynyl esters to homologated enoates at room temperature within a single vessel.

Ligand-controlled, norbornene-mediated, regio- and diastereoselective rhodium-catalyzed intramolecular alkene hydrosilylation reactions.

Ligand-controlled, norbornene-mediated, regio- and diastereoselective rhodium-catalyzed intramolecular alkene hydrosilylation of homoallyl silyl ethers (1) exploiting either BINAP or 1,6-bis(diphenylphosphino)hexane (dpph) has been developed. This method permits selective access to either trans-oxasilacyclopentanes (trans-2) or oxasilacyclohexanes (3) at will. A substoichiometric amount of norbornene markedly increased both yield and selectivity. A norbornene-mediated hydride shuttle process is discussed.