An N,N,N-type Cu(II) complex-catalyzed desaturation method for converting alcohols, ketones, lactones, and lactams to their α,β-unsaturated carbonyl compounds is reported. The dehydrogenation reaction can be conducted with a green terminal oxidant O without requiring strong acid/base or stoichiometric oxidants. The Cu(II) complex/TEMPO/O system uses a non-noble catalyst, and a green terminal oxidant as well as demonstrates high activity and functional group tolerance.
View Article and Find Full Text PDFHerein, a series of [ONSN]-type iron(III) complexes were synthesized. A binary catalytic system in combination with iron complexes and tetrabutylammonium bromide (TBAB) exhibited high activity for the synthesis of cyclic carbonates from CO (1 atm) and terminal epoxides at room temperature. Additionally, single-component iron complexes without using additional TBAB as nucleophiles also showed high activity for the cycloaddition of CO and terminal epoxides under 80 °C and 0.
View Article and Find Full Text PDFHerein, we have reported an environmentally friendly asymmetric aldol reaction between isatins and ketones catalyzed by double-hydrogen-bonded primary amine organocatalysts on water under mild conditions. Enantioenriched 3-hydroxy-2-oxindoles were obtained in high yields (up to 99%) and excellent stereoselectivities (up to 99 : 1 dr and 99% ee) under optimal conditions. Furthermore, the model reaction involving isatin and cyclohexanone was successfully scaled to 10 mmol with no reduction in yield or stereoselectivity.
View Article and Find Full Text PDFA variety of strategies for direct alkoxylation of the benzyl C-H bond have been developed toward the construction of benzyl ethers. The light-induced benzyl C-H bond alkoxylation provides an alternative strategy for the synthesis of these important intermediates. The photocatalyzed alkoxylation of the benzyl C-H bond has dominated by metal-catalyzed methods.
View Article and Find Full Text PDFHighly enantiopure and bioactive δ-valerolactones and pyrazolones, bearing α-all-carbon quaternary stereocentres, were successfully and sequentially prepared via a one-pot procedure starting from readily available, inexpensive materials, catalysed by a new chiral squaramide under mild reaction conditions. An organocatalytic Michael reaction afforded the valerolactones, while a one-pot Michael-hydrazinolysis-imidization cascade yielded the pyrazolones. This procedure is economically efficient and environmentally benign.
View Article and Find Full Text PDFCorrection for 'N-Primary-amine tetrapeptide-catalyzed highly asymmetric Michael addition of aliphatic aldehydes to maleimides' by Zhi-Hong Du et al., Org. Biomol.
View Article and Find Full Text PDFThe highly asymmetric Michael addition reaction between maleimides and aliphatic aldehydes catalyzed by low-loading β-turn tetrapeptides with excellent yields and enantioselectivities at room temperature was reported. α-Branched and α-unbranched aldehydes both are suitable nucleophiles. N-Aryl, alkyl and hydrogen maleimides all are well tolerated and led to high yields and enantioselectivities.
View Article and Find Full Text PDFβ-Turn tetrapeptides were demonstrated to catalyze asymmetric aldol reaction of α-branched aldehydes and α-carbonyl aldehydes, i.e. glyoxylates and α-ketoaldehydes, to biomimetically synthesize acyclic all-carbon quaternary center-bearing 1,4-dicarbonyls in high yield and excellent enantioselectivity under mild conditions.
View Article and Find Full Text PDFThe enantioselective cross-aldol reaction between o-hydroxyacetophenones and trifluoromethyl ketones catalyzed by chiral thiourea organocatalysts is reported. Gram-scale synthesis of the cross-aldol product was carried out, with no decrease in the yield and enantioselectivity. Furthermore, the cross-aldol products thus prepared were used in the preparation of medicinally interesting 3,5-diaryl-5-trifluoromethyl-2-isoxazoline and β-trifluoromethyl-β-tertiary hydroxy acid ester with high yield and enantiopurity.
View Article and Find Full Text PDFObjective: To describe clinical features of reversible splenial lesion syndrome (RESLES) in children.
Methods: Retrospectively analyzed clinical features of RESLES in children and compared differences between severe and non-severe group, classified by clinical global impression-scale; summarized clinical features of children with mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) from case series.
Results: 16 episodes of RESLES occurring in 15 Chinese children were analyzed, with 13 episodes having MERS and 3 episodes with epilepsy.
Objective: To explore the development and prognosis of the acute flaccid paralysis (AFP) associated with enterovirus 71 (EV71) infection through clinical follow-up study for clinical and magnetic resonance imaging (MRI) features based on the research progress of virology and pathology.
Method: Sixteen children with HFMD associated with AFP in hospital from May 1, 2011 to August 31, 2011 were investigated and the patients received intensive rehabilitation training. The 16 cases were divided into two groups (the recovery or the sequela) by if the muscle strength recovered to level 4 after intensive rehabilitation.