Highly asymmetric aldol reaction of isatins and ketones catalyzed by chiral bifunctional primary-amine organocatalyst on water.

Herein, 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. In addition, the catalyst was recovered via simple filtration and was subsequently reused on water, which highlights its good application potential.

Visible-Light-Driven Organocatalytic Alkoxylation of Benzylic C-H Bonds.

A 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. Herein, we reported a light-driven organocatalytic approach for alkoxylation of the benzyl C-H bond by the use of 9,10-dibromoanthracene as a photocatalyst and employing N-fluorobenzenesulfonimide as an oxidant. This reaction proceeds at room temperature and is capable of converting a variety of alkyl biphenyl and coupling partners, including a variety of alcohol and carboxylic acid, as well as peroxide, to the desired products under 400 nm light irradiation.

Highly enantioselective one-pot sequential synthesis of valerolactones and pyrazolones bearing all-carbon quaternary stereocentres.

Highly 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.

Correction: N-Primary-amine tetrapeptide-catalyzed highly asymmetric Michael addition of aliphatic aldehydes to maleimides.

Correction for 'N-Primary-amine tetrapeptide-catalyzed highly asymmetric Michael addition of aliphatic aldehydes to maleimides' by Zhi-Hong Du et al., Org. Biomol. Chem., 2020, 18, 6899-6904, DOI: 10.1039/D0OB01457E.

N-Primary-amine tetrapeptide-catalyzed highly asymmetric Michael addition of aliphatic aldehydes to maleimides.

The highly asymmetric Michael addition reaction between maleimides and aliphatic aldehydes catalyzed by low-loading ß-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. The transformation can be enlarged to the gram scale without decrease in the yield and enantioselectivity. Furthermore, the succinimides were converted into γ-lactams and γ-lactones, showing good practicality of this work. Some reaction intermediates in the proposed reaction mechanism can be captured with the HR-MS method.

Peptide-Catalyzed Highly Asymmetric Cross-Aldol Reaction of Aldehydes to Biomimetically Synthesize 1,4-Dicarbonyls.

ß-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. The spatially restricted environment of the tetrapeptide warrants high enantioselectivity and yield with broad substrates. Using this protocol, (R)-pantolactone, the key intermediate of vitamin B5, was readily accessed in a practical, efficient, and environmentally benign process from inexpensive starting materials.

Organocatalytic Enantioselective Cross-Aldol Reaction of o-Hydroxyarylketones and Trifluoromethyl Ketones.

The 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 ß-trifluoromethyl-ß-tertiary hydroxy acid ester with high yield and enantiopurity.

Reversible splenial lesion syndrome in children: Retrospective study and summary of case series.

OBJECTIVE: 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. 10 episodes were associated with various pathogens including rotavirus (n=5), adenovirus (n=1), influenza A (n=1), mycoplasma (n=2), and jejunum campylobacter (n=1). The common neurological symptoms included seizure, behavioral changes, altered consciousness and motor deterioration. The lesions of splenium of corpus callosum (SCC), extra-SCC (n=2) or extra-CC (n=1) showed T2-weight and FLAIR hyper-intensity, with the corresponding reduced diffusion. All had complete resolution of radiological changes except 1 episode with small residual. 8 episodes had EEG abnormalities, while elevated white blood count, increased hs-CRP, and hyponatremia were commonly revealed. 7 episodes were given steroid plus therapy, while 3 episodes were treated with antiepileptic drugs. Compared with non-severe group, the number of patients with altered consciousness, EEG abnormalities, motor deterioration, or extra-SCC lesions in severe group was significantly increased. The patients in severe group tended to need longer hospital stay interval. No case caused neurological sequelae, except 1 patient in severe group with recurrent episode and extra-CC lesions having intellectual disability (ID). Five pediatric MERS case series were summarized, including 67 episodes (40 male and 27 female; age ranging 10 m∼13y) from 65 patients, with 33 episodes in Japan, 27 in China, and 7 in Caucasian Australian children, and all patients have a good prognosis except 1 patient with ID (current study). CONCLUSION: Although RESLES in children tend to be a good outcome, the prognosis of patient in severe group, especially with extra-CC lesions, might have neurological sequelae.

[Evolution and prognosis of the acute flaccid paralysis associated with enterovirus 71 infection evaluated through a clinical and magnetic resonance imaging follow-up study].

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. The MRI findings of 15 children were analyzed and among them, 6 patients were reexamined after one month. The clinical markers were compared between groups including course of disease, WBC, WBC in cerebrospinal fluid (CSF), ventilator support, therapy, the worst muscle strength, the initial tendon reflex, the muscle atrophy, and multi-limb paralysis. The data were analyzed by t test and χ2 test with SPSS10.0. RESULT: All the 16 children were infected with enterovirus 71 (EV71). The myodynamia of 7 children were level 0, 4 children had serious upper limbs paralysis. The neck muscle in 3 cases and the brain stem motor ruckus in 4 cases were involved. The ankle clonus of non-completely paralyzed limbs in 14 cases occurred during rehabilitation. Eight children had the better prognosis, the other 8 children had sequela. 0 level muscle strength (0 case vs. 7 cases, χ2=12.4), the initial tendon reflex (2 cases vs. 8 cases, χ2=9.6), obvious muscle atrophy (0 case vs. 8 cases, χ2=16), were significantly different in the children with the recovery when compared to the sequela (P<0.01). The severe upper limbs paralysis had the worse prognosis than the severe lower limbs paralysis. MR imaging showed signs of spinal nerve root inflammation and the bilateral hyperintense lesions, symmetrical in the posterior portions of the medulla, pons, and asymmetrical in the ventral horns of cervical spinal cord. Signal enhancement occurred only in the early MRI examination. CONCLUSION: In the evolution of AFP due to EV71 infection, the upper motor neuron damage is common, the prognosis is related with the severity of early paralysis and neuron damage. MR imaging is helpful to understand the pathological mechanism of AFP.