A study of diketopiperazines as electron-donor initiators in transition metal-free haloarene-arene coupling

Several diketopiperazines have been shown to promote carbon-carbon coupling between benzene and aryl halides in the presence of potassium tert-butoxide and without the assistance of a transition metal catalyst. The structure of the diketopiperazine has an influence on its reductive potential and can help to promote the coupling of the more challenging aryl bromides with benzene

Study on the trend of congenital heart disease inpatient costs and its influencing factors in economically underdeveloped areas of China, 2015–2020: a case study of Gansu Province

BackgroundEconomic data on congenital heart disease are scarce in economically underdeveloped areas of China. Therefore, this study aimed to shed light on the level and changing trend of congenital heart disease inpatients' economic burden in underdeveloped areas.MethodThis study used a multi-stage stratified cluster sampling method to select 11,055 inpatients with congenital heart disease from 197 medical and health institutions in Gansu Province. Their medical records and expenses were obtained from the Hospital Information System. Univariate analysis was conducted using the rank sum test and Spearman rank correlation. Quantile regression and random forest were used to analyze the influencing factors.ResultsFrom 2015 to 2020, the average length of stay for congenital heart disease patients in Gansu Province was 10.09 days, with an average inpatient cost of USD 3,274.57. During this period, the average inpatient costs per time increased from USD 3,214.85 to USD 3,403.41, while the average daily inpatient costs increased from USD 330.05 to USD 376.56. The average out-of-pocket costs per time decreased from USD 2,305.96 to USD 754.77. The main factors that affected the inpatient costs included length of stay, cardiac procedure, proportion of medications, age, and hospital level.ConclusionCongenital heart disease causes a significant economic burden on both families and society. Therefore, to further reduce the patient's financial burden, the length of stay should be reasonably reduced, and the rational distribution of medical resources should be continuously promoted to ensure equitable access to healthcare services

Electron transfer-induced coupling of haloarenes to styrenes and 1,1-diphenylethenes triggered by diketopiperazines and potassium tert-butoxide

The coupling of haloarenes to styrenes and 1,1-diarylethenes has been achieved with potassium tert-butoxide in the presence of N,N'-dialkyldiketopiperazines. In contrast to previously reported reactions where phenanthroline has been used to mediate the reactions, the use of diketopiperazines can lead to either 1,1,2-triarylethenes or 1,1,2-triarylethanes, depending on the conditions used

Proton transfer reactions of a bridged bis-propyl bis-imidazolium salt

Tetraazafulvalene 1 has found broad application in reduction and other related transformations and is conveniently generated from bis-propyl bis-imidazolium salt 4 with a strong base in a non-protic solvent. The proposed mechanism for the formation of 1 involves initial deprotonation at C(2) to give a mono-carbene 9 followed by intramolecular reaction at the second azolium centre. Herein, we report the second-order rate constants for deuteroxide-catalysed exchange in aqueous solution of the C(2)-hydrogens of bis-propyl bis-imidazolium di-iodide salt 4 and related monomeric dipropyl imidazolium iodide 10 of kDO = 1.37 × 104 and 1.79 × 102 M−1 s−1, respectively, and used these data to calculate pKa values of 21.2 and 23.1. The greater C(2)-H acidity of the doubly bridged bis-propyl bis-imidazolium salt 4 relative to 10 may be attributed to the inductive or electrostatic destabilization of the conjugate acid dicationic azolium ion 4 relative to the monocationic carbene 9, which is enhanced by bis-tethering. Formation of tetraazafulvalene 1 was not observed under the aqueous conditions employed highlighting that carbene reprotonation significantly outcompetes dimerization under these conditions

Identifying the roles of amino acids, alcohols and 1,2-diamines as mediators in coupling of haloarenes to arenes

Coupling of haloarenes to arenes has been facilitated by a diverse range of organic additives in the presence of KO(t)Bu or NaO(t)Bu since the first report in 2008. Very recently, we showed that the reactivity of some of these additives (e.g., compounds 6 and 7) could be explained by the formation of organic electron donors in situ, but the role of other additives was not addressed. The simplest of these, alcohols, including 1,2-diols, 1,2-diamines, and amino acids are the most intriguing, and we now report experiments that support their roles as precursors of organic electron donors, underlining the importance of this mode of initiation in these coupling reactions