The First Example of the Friedel-Crafts Cyclization Leading to (10-Hydroxy-9,10-dihydroanthr-9-yl)phosphonium Salts without the Expected Bradsher Dehydration.

The reaction of (ortho-acetalaryl)arylmethanols with various phosphines PR1R2R3 (R1 = R2 = R3 = Ph; R1 = R2 = Ph, R3 = Me and R1 = R2 = Me, R3 = Ph) under acidic conditions (e.g., HCl, HBF4, TsOH) unexpectedly led to the formation of (10-hydroxy-9,10-dihydroanthr-9-yl)phosphonium salts instead of the corresponding anthryl phosphonium salts. The cyclization occurred according to the Friedel-Crafts mechanism but without the usually observed Bradsher dehydration, giving cyclic products in the form of cis/trans isomers and their conformers. In case of electron-rich and less-hindered dimethylphenylphosphine, all four stereoisomers were recorded in 31P{1H} NMR spectra, while for the other phosphines, only the two most stable cis/trans stereoisomers were detected. This study was supported by DFT and NCI calculations in combination with FT-IR analysis.

Comprehensive Review on Synthesis, Properties, and Applications of Phosphorus (PIII, PIV, PV) Substituted Acenes with More Than Two Fused Benzene Rings.

This comprehensive review, covering the years 1968-2022, is not only a retrospective investigation of a certain group of linearly fused aromatics, called acenes, but also a presentation of the current state of the knowledge on the synthesis, reactions, and applications of these compounds. Their characteristic feature is substitution of the aromatic system by one, two, or three organophosphorus groups, which determine their properties and applications. The (PIII, PIV, PV) phosphorus atom in organophosphorus groups is linked to the acene directly by a P-Csp2 bond or indirectly through an oxygen atom by a P-O-Csp2 bond.

Learners' Perspective towards E-Exams during COVID-19 Outbreak: Evidence from Higher Educational Institutions of India and Saudi Arabia.

Online examinations, commonly referred to as e-exams (electronic examinations), underwent a considerable progression, getting adapted ubiquitously among higher education institutions worldwide. Their preferment was rapid due to the emergence of the COVID-19 pandemic. The process of conducting exams online is being opted as the appropriate way of assessment, ensuring the students' safety and well-being. According to Warts et al., this form of examination has been pretty effective in the past when blended with the conventional assessment. However, at present, implemented as the singular way of assessment, e-exams have shown a more significant promise in being beneficial to the learners. As a matter of fact, a comprehensive analysis on understanding the learners' perception towards the e-exams was not done earlier, particularly in the developing nations. Thus, it was pertinent to examine the pre-requisites of e-exams to promote it as a useful tool for the smooth conduct of exams in the aforesaid nations. Against such a backdrop, this study was conducted during January to March 2021 on 207 students enrolled in four universities, three situated in the National Capital Territory (NCT) of Delhi, India: Delhi University (DU), Jamia Millia Islamia (JMI), and Jawaharlal Nehru University (JNU), and one situated in Saudi Arabia, namely Saudi Electronic University (SEU). A quantitative approach was employed for the study, with the responses recorded via web questionnaires. Confirmatory -factor analysis (CFA) was applied in the study to examine whether the process of conducting online examinations is being chosen as the appropriate form of assessment, ensuring the safety and well-being of students through AMOS (version 24) software. For determining the reliability of the two latent constructs, namely "Perceptions of students towards E-exams (PSE)" and "Pre-requisites of E-exams (POE)," Cronbach's alpha was used through SPSS (version 25) software in the study, and the results reveal that the strong internal consistency exists between all the measured variables. In addition, the mean and standard deviation were used by the researchers to find out the pre-requisites of the online examination system. The participants expressed their insights on the relative benefits of online examination. Their perception was based on pedagogy, validity and reliability, affective factors, practicality, and security. From their insights, it was concluded that online examination is more advantageous than conventional paper-based exams. The outcome also applies to the authenticity of grading and the overall efficiency concerning the time, effort, and expenditure on conducting the examination. Contrarily, the participating students also recognized numerous hurdles in implementing e-exams concerning security, validity, and impartiality. The conclusion further revealed that online examination is especially relevant for formative assessment of learning instead of summative assessment, provided authenticity, security, and flexibility are used as fundamental tenants in the proper implementation of e-exams. The outcome of the present study will facilitate higher education institutions and policymakers in taking the electronic examination system to the next level.