N-Heterocyclic Carbene-Catalyzed Oxidative Annulations of α,ß-Unsaturated Aldehydes with Hydrazones: Selective Synthesis of Optically Active 4,5-Dihydropyridazin-3-ones and Pyridazin-3-ones.

A novel and efficient method for the highly enantioselective synthesis of chiral 4,5-dihydropyridazin-3-one derivatives has been developed based on the chiral N-heterocyclic carbene-catalyzed oxidative annulation between α,ß-unsaturated aldehydes and hydrazones. Meanwhile, the selective synthesis of either 4,5-dihydropyridazin-3-ones or pyridazin-3-one derivatives from the same reactants has been achieved by simply varying catalytic and reaction conditions.

Clinical characteristics and neurologic recovery of patients with cervical spinal tuberculosis: should conservative treatment be preferred? A retrospective follow-up study of 115 cases.

OBJECTIVE: To present the clinical characteristics and prognostic factors of neurologic recovery in patients with cervical spinal tuberculosis (CST). METHODS: General description and multivariate analysis were used to detect possible predictors of the outcome of patients with neurologic deficit. Follow-up data were used to generate a Kaplan-Meier curve of neurologic recovery. RESULTS: Protective factors in neurologic recovery included less involved vertebrae, surgery, and higher Japanese Orthopaedic Association score before treatment; not shorter symptom duration was not a protective factor. Normal neurologic function was present in 30% of patients 6 months after treatment, in 56% of patients 12 months after treatment, and in 93% of patients 28 months after treatment. The cumulative complete neurologic recovery rates at 6 months, 12 months, and 28 months were 44%, 68%, and 91.7% in the surgery group and 16.7%, 38.8%, and 94.4% in the nonsurgery group. CONCLUSIONS: Surgery and Japanese Orthopaedic Association score before treatment are important predictors of neurologic recovery in patients with CST. A neurologic recovery curve could predict neurologic recovery in patients with CST and indicate in patients with neurologic deficit how long it will take to achieve complete neurologic recovery. The effect of surgery is quick, and the effect of conservative treatment is slower, but no difference in neurologic recovery was found in the long-term. Conservative treatment should be tried in every patient with CST with no obvious indication for surgery. In contrast to patients with tuberculosis without cervical spine involvement but with more complications, comprehensive conservative therapy should be preferred for patients with neurologic deficit to avoid unnecessary surgery and overtreatment and to conserve medical resources. Indications for surgical intervention for CST should be carefully selected.

N-heterocyclic carbene-catalyzed diastereoselective and enantioselective reaction of 2-aroylvinylcinnamaldehydes with α,ß-unsaturated imines: complete control and switch of diastereoselectivity by N-substituents of catalysts.

Highly diastereoselective and enantioselective reactions between 2-aroylvinylcinnamaldehydes and α,ß-unsaturated imines were achieved under asymmetric catalysis of chiral triazole carbene catalysts. In the presence of N-anisylindeno[2,1-b]triazolo[4,3-d][1,4]oxazinium salt, the reaction of 2-aroylvinylcinnamaldehydes with α,ß-unsaturated imines afforded indeno[2,1-c]pyran-1-one derivatives 4 with 90%-99% ee, while enantiopure indenocyclopentan-1-ones 5 (>99% ee) were obtained under the catalysis of N-mesitylindeno[2,1-b]triazolo[4,3-d][1,4]oxazinium salt. A slight variation of an N-substituent on triazole carbenes was found to switch completely the diastereoselectivity of the reaction for the formation of indeno[2,1-c]pyran-1-ones.

Changing reaction pathways of the dimerization of 2-formylcinnamates by N-heterocyclic carbene/Lewis acid cooperative catalysis: an unusual cleavage of the carbon-carbon bond.

Catalyzed by a triazole carbene, the dimerization of 2-formylcinnamates underwent benzoin condensation followed by intramolecular oxa-Michael addition to afford isochromeno[4,3-c]isochromene products. Under the catalysis of a combination of triazole carbene and Ti(OPr-i)4 catalysts, the dimerization reaction of 2-formylcinnamates proceeded through a completely different route to furnish the formation of isochromenone derivatives with the elimination of an acetate moiety.