Bouveret's syndrome: a rare presentation of a common surgical enigma.

Bouveret syndrome, an uncommon complication of cholelithiasis, typically manifests with symptoms of gastric outlet obstruction. Despite its rarity, Bouveret syndrome carries significant morbidity and mortality. This paper presents a case study and explores diagnostic approaches and management options for this challenging condition.

Exploiting N-Centered Umpolung Reactivity of α-Iminomalonates for the Synthesis of N-Sulfenylimines and Sulfonamides.

An efficient and interesting N-centered umpolung method has been disclosed to construct beneficial S-N bonds, furnishing N-sulfenylimines, which can readily be converted into the corresponding sulfonamide derivatives in a one-pot sequential operation. N-Sulfenylimines are potent intermediates in organic synthesis, whereas sulfonamides are of major molecular interest due to their rich biological activities and wide applicability in medicinal chemistry. Owing to the simple reaction conditions and setup, this protocol displays a broad and versatile substrate scope, resulting in excellent functional group tolerability toward the synthesis of both N-sulfenylimines and sulfonamides. A density functional theory (DFT) computed and experimentally supported convenient mechanism has been proposed for this unique method.

Introducing N-Sulfinylamines into Visible-Light-Induced Carbene Chemistry for the Synthesis of Diverse Amides and α-Iminoesters.

A rare example of visible-light-mediated diverse reactivity of N-sulfinylamines with different types of carbene precursors has been disclosed. Acylsilanes and aryldiazoacetates have been utilized as nucleophilic and electrophilic carbene precursors into the N═S═O linchpin, to achieve valuable amides and α-iminoesters, respectively. Interestingly, diazocarbonyls can also participate in the amidation reaction with N-sulfinylamines via in situ generated ketenes. This operationally simple modular method offers a mild, transition-metal-free, and coupling-reagent-free protocol to fabricate structurally diverse amides and a promptly accessible technique to achieve α-iminoesters, where visible light remains as a key promoter.

C(sp3)-C(sp3) Radical-Cross-Coupling Reaction via Photoexcitation.

The photoexcitation of 4-alkyl-1,4-dihydropyridines (alkyl-DHPs) in the presence of a base triggers the single-electron-transfer-mediated desulfonative radical-cross-coupling (RCC) reaction without the need for any metal or photocatalyst. 4-Alkyl-substituted 1,4-DHPs as the electron donor (reductant) and alkyl sulfones as the electron acceptor (oxidant) are chosen strategically as the two best-matched modular radical precursors for the construction of C(sp3)-C(sp3) bonds. Ultraviolet light-emitting diodes (365 nm) have proven to be adequate for inducing single-electron transfer between two radical precursors in the excited state. Following this designed strategy, a diverse collection of primary, secondary, and tertiary persistent alkyl radicals from both radical precursors have been used to forge C(sp3)-C(sp3) bonds. This blueprint features good functional group compatibility, a broad scope, and detailed mechanistic investigation.

Metal-free thiolation of sulfonyl hydrazone with thiophenol: synthesis of 4-thio-chroman and diarylmethyl thioethers.

A simple, efficient, and transition metal-free approach was developed for accessing 4-thio-substituted chroman and diarylmethyl thioethers from sulfonyl hydrazones. This protocol provides straightforward access to a class of diarylmethane derivatives with good to excellent yields. This operationally simple protocol exhibited good tolerance for labile functional groups, providing biologically relevant chemical libraries. This safe and feasible route is applicable to the large-scale synthesis of 4-thio-substituted chromans, which are of great synthetic interest because of their further reaction potential.

The effect of cochlear implant age and duration of intervention on ESRT in children with cochlear implant.

OBJECTIVE: To study the effect of cochlear implant age and duration of the intervention (auditory rehabilitation post-cochlear implantation) on ESRT in children with cochlear implants. METHODS: A total of 90 pre-lingual cochlear implant users were included. For the measurement of ESRTs the recipient's processor was connected to the programming pod and electrode numbers 22, 11 and 3 (apical, middle and basal), respectively, were activated to give stimulation sequentially and elicit deflection as a response. RESULTS: There were significant differences in the measured T, C and ESRT levels with respect to the duration of the intervention (auditory rehabilitation post-cochlear implantation) and cochlear implant age obtained at p < 0.05*, 0.01**. DISCUSSION: The differences in the T, C and ESRT levels after continued device usage and after attending auditory rehabilitation sessions post-cochlear implantation are subjected to optimal benefit from implantation during the critical period. CONCLUSION: The differences in T, C and ESRT levels can be utilised clinically to study the importance of duration of cochlear implant device usage and the importance of auditory rehabilitation post-cochlear implantation in children with cochlear implantation.

In-Catalyzed Transfer Hydrogenation and Regioselective Hydrogen-Deuterium Addition to the Olefins.

A unique and valuable methodology is developed for the hydrogenation of aromatic as well as aliphatic 1,1-di- and trisubstituted alkenes. In the presence of catalytic InBr3, readily available 1,3-benzodioxole and residual H2O present in the reaction mixture are utilized as a hydrogen gas surrogate and proved to be a practical source of deuterium incorporation into the olefins on either side by varying the source of the starting deuterated 1,3-benzodioxole or D2O. Experimental studies show the transfer of hydride from 1,3-benzodioxole to the carbocationic intermediate generated from the protonation of alkenes by the H2O-InBr3 adduct remains the critical step.

Palladium-catalyzed regioselective synthesis of mono and bis(arylthiol) alkenes from propargyl carbonate and thiophenol.

A palladium catalyzed regioselective reaction of propargylic carbonate with thiophenols and benzene selenol is described. Atom-economic addition of thiols to propargylic carbonates provides an excellent opportunity for effective processes. The reaction proceeds via hydrothiolation to produce mono(arylthiol) alkenes and hydrothiolation followed by Tsuji-Trost type substitution to form bis(arylthiol) alkenes through single and double sequential attack by soft thio nucleophiles by control of the equivalence of thiophenols. This coupling reaction with good tolerance towards functional groups in both propargylic carbonates and thiols furnished a variety of highly functionalized alkenylation products in moderate to excellent yields via the formation of new C-S and C-Se bonds.

Copper-Catalyzed Regioselective Remote C-H Bond Chalcogenation of Aromatic Amine Derivatives without Using Any Large Template.

A mild and convenient strategy has been developed for the para-selective chalcogenation of anilide scaffolds via C-H bond functionalization. This methodology employs one of the most earth-abundant and inexpensive Cu(II) catalysts and a commercially available simple aryl chalcogen source without any complex directing template, exogenous ligand, acid/base, oxidant, or other additives. The key feature of this methodology is an impressive regioselectivity along with a wide range of functional group tolerance with good to excellent yields under aerobic conditions.

A Synthetic Overview of Benzoxazines and Benzoxazepines as Anticancer Agents.

Benzoxazines and benzoxazepines are nitrogen and oxygen-containing six and seven-membered benzo-fused heterocyclic scaffolds, respectively. Benzoxazepines and benzoxazines are well-known pharmacophores in pharmaceutical chemistry, which are of significant interest and have been extensively studied because of their promising activity against various diseases including their wide range of anticancer activity. Several reports are known for synthesizing benzoxazine and benzoxazepine-based compounds in the literature. Herein this review provides a critical analysis of synthetic strategies towards benzoxazines and benzoxazepines along with various ranges of anticancer activities based on these molecules that have been reported from 2010 onwards. This review also focuses on the structure-activity relationship of the benzoxazine and benzoxazepine scaffolds containing bioactive compounds and describes how the structural modification affects their anticancer activity.

Photoredox Catalyzed Single C-F Bond Activation of Trifluoromethyl Ketones: A Solvent Controlled Divergent Access of gem-Difluoromethylene Containing Scaffolds.

Selective defluorinative functionalization of trifluoromethyl ketones is a long-standing challenge owing to the exhaustive mode of the process. To meet the demands for the installation of the gem-difluoromethylene unit for the construction of the molecular architectures of well-known pharmaceuticals and agrochemicals, a distinct pathway is thereby highly desirable. Here, a protocol is introduced that allows the divergent synthesis of gem-difluoromethylene group containing tetrahydrofuran derivatives and linear ketones via single C-F bond activation of trifluoromethyl ketones using visible-light photoredox catalysis in the presence of suitable olefins as trapping partner. The choice of appropriate solvent and catalyst plays a significant role in controlling the divergent behavior of this protocol. Highly reducing photo-excited catalysts are found to be responsible for the generation of α,α-difluoromethyl ketone (DFMK) radicals as the key intermediate via a SET process. This protocol also results in a high diastereoselectivity towards the formation of partially fluorinated cyclic ketal derivatives with simultaneous construction of one C-C and two C-O bonds. State-of-the-art DFT calculations are performed to address the origin of diastereoselectivity as well as the divergence of this protocol.

Redox-active alkylsulfones as precursors for alkyl radicals under photoredox catalysis.

A method for generating alkyl radicals using visible-light photoredox catalysis is described. This procedure was found to present an efficient means to access a diverse collection of 1°, 2°, and 3° alkyl radicals through the single-electron transfer of sulfones under mild reaction conditions. These alkyl radicals generated via the reductive desulfonylation of readily synthesized and stable alkylsulfones were engaged to forge C-C bonds. A detailed study was also carried out to shed light on the mechanism.

Transition-Metal-Free Regioselective Intermolecular Hydroamination of Conjugated 1,3-Dienes with Heterocyclic Amines.

The unique property of hexafluoroisopropanol (HFIP) enables the regioselective hydroamination of 1,3-dienes with nitrogen heterocycles in a Markovnikov manner in the presence of catalytic Brønsted acid. This transition-metal-free intermolecular hydroamination protocol is achieved under mild reaction conditions. The aggregation by HFIP and Brønsted acid helps to activate the terminal double bond regioselectively. Following the protonation of diene, the C-N bond formation is accomplished upon the involvement of heterocyclic amines.

Visible-Light-Mediated (sp 3)Cα-H Functionalization of Ethers Enabled by Electron Donor-Acceptor Complex.

A synthetically beneficial visible-light-mediated protocol has been disclosed to achieve C-H amination of readily available feedstocks cyclic and acyclic ethers. A rarely identified N-bromosuccinamide-tetrahydrofuran electron donor-acceptor complex served as an initiator to functionalize both α-diazoketones and dialkyl azodicarboxylates. This developed methodology gives an alternative and milder way to construct the C-N bond and can be explored for the formation of C-C bond to perform arylation and allylation reactions.

HFIP-Assisted Single C-F Bond Activation of Trifluoromethyl Ketones using Visible-Light Photoredox Catalysis.

A visible light photoredox catalytic method for the selective cleavage of single strong C-F bond in trifluoromethyl ketones is reported. Single electron reduction of trifluoromethyl ketones generates difluoromethyl radicals which can be engaged in intermolecular C-C bond formation with N-methyl-N-arylmethacrylamides to furnish fluorine-containing oxindole derivatives in good yields. The reaction shows excellent chemoselectivity with good functional group tolerance under mild conditions. 1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) as a solvent plays a critical role for the selective single C-F bond cleavage. High-level DFT calculations are depicted to shed light on the mechanism.

A Comparative Study on Acoustic Voice Quality Index Between the Subjects with Spasmodic Dysphonia and Normophonia.

Spasmodic dysphonia is one of the neurologic voice disorders that is rare, chronic and long term caused by excessive or inappropriate contraction of the laryngeal muscles. The condition is more common in females than males. Assessment of such disorders requires acoustic, perceptual, instrumental and self-reported rating scales for effective diagnosis and intervention. The Acoustic Voice Quality Index is a recent, multivariate acoustic measure of dysphonia measuring the overall quality of voice including both vowels and connected speech in Praat software using AVQI script. The study aimed at comparing, observing and analysing the thresholds of AVQI obtained in the two groups. The study also targeted to show an effective co relation between GRBAS scale and thresholds of AVQI using sustained vowel /α/ and Bengali oral passage. A total of 14 participants were chosen with age range 20-50 years, 7 participants were normophonic and 7 participants were having spasmodic dysphonia. Comparison was done between the 2 groups showing a significant difference (p < 0.05) between the groups. A strong co relation was obtained (α = 0.98) between two scales. Thus AVQI does the job of appropriate diagnostic tool for obtaining the scores of dysphonic population and need to be explored in other voice problems.

A Comparative Acoustic Analysis of Bangla Folk Song and RabindraSangeet on Long-Term Average Spectrum.

BACKGROUND: Singing is defined as a sensory-motor phenomenon that requires particular balanced physical skills such as respiration, phonation, resonance, and articulation. The long-term average spectrum (LTAS) is widely accepted as a robust and effective tool for the assessment of voice characteristics. METHOD: Eighty female singers within the age range of 18-30 years were considered for the study. Among 80 participants, 40 were asked to perform one traditional song from Bangla Folk representing the Baul style and another 40 were asked to perform a traditional song from Rabindra Sangeet. Recordings were done and then acoustic (LTAS) analyses were done through PRAAT software. Statistical analyses were done for the analyzed data. software package of social sciences (Version 20.0) was used. RESULTS: The averaged LTAS curve of Baul style showed a broad peak in the frequency range between 2000 and 3600Hz and its amplitude about 16 dB, Rabindra Sangeet showed a broader peak in the frequency range between 2200 and 3800 Hz and its amplitude about 15 dB. This evidence showed the presence of singer's formants in both singing styles. CONCLUSION: It can be concluded from the present study that, there is an acoustical difference between the Bangla Folk and Rabindra Sangeet singing style which can be evidenced using LTAS through PRAAT.

Boron-Catalyzed Hydroarylation of 1,3-Dienes with Arylamines.

Catalytic hydroarylation reactions of conjugated dienes are achieved using tris(pentafluorophenyl)borane as a Lewis acid catalyst under mild reaction conditions. This new protocol shows a broad substrate scope for the highly regioselective functionalization of sterically hindered aniline derivatives. Experimental and extensive density functional theory mechanistic studies show that the complex of residual water and B(C6F5)3 plays a crucial role in the aryl-assisted protonation of conjugated dienes, forming allyl cation intermediates that induce the facile electrophilic aromatic substitution of aniline substrates.