Reaction of N-tosylaziridines with nitriles and carbonyls to produce imidazolines and oxazolidines has been studied in the presence of a variety of Lewis acids. The reaction is efficient with 1 equiv of BF3.Et2O or Et3OBF4 in CH2Cl2. However, it is catalytic with metal triflates that give the best results for cycloaddition of N-tosylaziridine with nitriles under solvent free conditions. The same reaction with carbonyls proceeds best in CH2Cl2 in the presence of molecular sieves. Among various triflates, Zn(OTf)2 has been found to be the best. The cleavage of the N-Ts bond of the cyclized products has been studied in order to make it more versatile in synthesis. The mechanistic aspect of the reaction has been studied by using chiral aziridines as substrates. These formal [3+2] cycloaddition reactions of aziridines with nitriles and carbonyls proceed in a Ritter fashion.
It takes three to make things go right: The first direct asymmetric three-component reaction of aldehydes, carbamates, and allyltrimethylsilane leading to enantioenriched homoallylic amines has been developed using a new chiral disulfonimide catalyst. The method employs readily available, inexpensive, and nontoxic starting materials and is applicable to both aromatic and aliphatic aldehydes.
We report the synthesis of a new series of highly efficient chiral organocatalysts derived via the regio- and stereoselective ring opening of chiral aziridines with azide anions. The catalysts have proved to be very efficient for a direct asymmetric aldol reaction, both with cyclic as well as acyclic ketones in brine with 2 mol % of catalyst loading, and afforded the products in excellent yields (up to 99%) and enantioselectivities (up to >99%). The chiral aldol adduct obtained has further been converted to a chiral azetidine ring via a convenient pathway.
ObjectiveTo assess the inpatient hospitalization burden and costs of patients with autoimmune encephalitis (AE) at a tertiary care institution.MethodsAdult inpatients with AE were identified retrospectively from July 1, 2005, to June 30, 2015. Demographic and clinical data were collected and analyzed. Billing data were compared to those of patients with herpes simplex encephalitis (HSE). Charges were adjusted for inflation.ResultsOf 244 admissions for encephalitis reviewed, 63 patients met criteria for probable or definite AE. Thirty-one (49%) patients were antibody positive, and 27 (43%) were admitted to the intensive care unit (ICU). Median hospital charges per patient with AE were more than $70,000; median length of stay (LOS) was 15 days; and in-hospital mortality was 6%. Patients admitted to the ICU had substantially higher median hospital charges (ICU $173,000 per admission vs non-ICU $50,000 per admission, p < 0.001). LOS was strongly associated with charges and was driven by delay in diagnosis of AE, prolonged treatment courses, and lack of response to therapy. Compared with HSE, median hospital charges per patient with AE were nearly 4 times higher, median AE LOS was 3 times higher, and total charges over the study period were nearly twice as high.ConclusionsPatients with AE used more inpatient health care resources per patient during a 10-year period than patients with HSE at our institution. ICU-admitted patients with AE were responsible for a substantially higher financial burden than non–ICU-admitted patients with AE. Our data underscore the need for the development of novel diagnostic and therapeutic modalities to improve patient outcomes and to decrease hospital burden in AE.
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