ABSTRACT
Alkali metal alkoxides play a pivotal role in nucleophilic alkoxylation reactions, offering pathways for the synthesis of ethers, including the increasingly sought-after trifluoromethyl ethers. However, the synthesis of long-chain perfluoroalkyl ethers remains a substantial challenge in this field. Through the innovative use of triglyme to encapsulate potassium ions, we enhanced the stability of short-lived, longer-chain perfluoroalkoxy anions, thereby facilitating efficient nucleophilic perfluoroalkoxylation reactions. This method provides a new precedent for the halo-perfluoroalkoxylation of gem-difluoroalkenes and offers a versatile tool for the design of perfluoroalkyl ethers, including those containing complex moieties of heterocycles and drug molecules. We also demonstrated the utility of the resulting halo-perfluoroalkoxyl adducts through various chemical transformations to valuable diverse perfluoroalkyl ethers.
ABSTRACT
This study introduces a dual-catalytic method for cross-dehydrogenative coupling (CDC) between tetrahydroisoquinolines and Py-SF4-alkyne using visible-light photoredox catalysis. This protocol enables selective C(sp3)-H alkynylation, expanding the synthetic toolkit for SF4-based molecules. Demonstrating efficiency and substrate versatility, this approach opens new avenues in hexacoordinated tetrafluorinated sulfur chemistry and CDC strategies and holds significant promise for drug discovery and materials science.
ABSTRACT
gem-Difluoromethylene moieties are attractive in medicinal chemistry due to their ability to mimic other more ubiquitous functional groups. Thus, effective asymmetric methods for their construction are highly desirable, especially for the industrial production of chiral drugs. Using a Pd-catalyzed asymmetric [4+2] cycloaddition between substituted-2-alkylidenetrimethylene carbonates and gem-difluoroalkyl ketones, we were able to easily access chiral 1,3-dioxanes that contain a tetrasubstituted difluoroalkyl stereogenic center in cyclic and acyclic skeletons. A novel phosphoramidite ligand, which contains a bulky 1,1-dinaphthylmethanamino moiety, was developed to provide the products in high yield with excellent enantio-, diastereo-, and regioselectivity. Strikingly, the gem-difluoro substitution pattern promotes the reaction, and pentafluoroethylketone, an α,α-difluorinated ß-ketoester, and a ß-ketosulfone are suitable substrates for this method.
Subject(s)
Hydrocarbons, Fluorinated , Palladium , Catalysis , Cycloaddition ReactionABSTRACT
BACKGROUND AND AIM: Although pretreatment with a sedative drug is effective in relieving pain during esophagogastroduodenoscopy (EGD), such drugs can cause significant side-effects. The aim of this study was to examine the effect of slow-wave photic stimulation on discomfort and/or pain felt during EGD. METHODS: Forty consecutive patients (25 men and 15 women) who underwent diagnostic EGD in our hospital were included in the study. Twenty patients received photic stimulation for 25 min, and underwent electroencephalographic recording, in addition to the usual premedications. Twenty control patients received the same treatment but without photic stimulation. All patients evaluated the discomfort/pain felt during endoscopy against a five-grade scale in comparison with what they had experienced in their previous examination. RESULTS: Patients with an improved discomfort/pain score were 18/20 and 3/20 in the treated and control groups, respectively. Overall comparison of pain scores between both groups was significant (P<0.0001). The proportion of slow-wave activity recorded in patients' electroencephalograms significantly increased in the treated group compared to control values (36.6+/-6.8% vs 29.1+/-3.4%, P<0.001). There was a close correlation between the degree of discomfort/pain felt during endoscopy and the proportion of slow-wave activity (P<0.001). CONCLUSION: Slow-wave photic stimulation shows promise as a treatment for relieving the discomfort and/or pain felt by patients undergoing EGD.
