Cycloaddition of Huisgen 1,4-dipoles: synthesis and rapid epimerization of functionalized spiropyrido[2,1-b][1,3]oxazine-pyrroles and related products.

1,4-Dipolar cycloaddition has emerged as a powerful tool for the synthesis of various cyclic compounds. In the present work, 1H-pyrrole-2,3-diones are proposed as new dipolarophiles for 1,4-dipolar cycloaddition. Their [4 + 2] cycloaddition with dipoles generated from dimethyl acetylenedicarboxylate and pyridine was found to proceed regioselectively affording spiro[pyrido[2,1-b][1,3]oxazine-2,3'-pyrroles] as diastereomeric mixtures which exist in rapid equilibrium in solution. It was established that this phenomenon of rapid epimerization is a characteristic of other similar spiropyrido[2,1-b][1,3]oxazines and even related spiroquinolizines, which was demonstrated by the investigation of related products of previously reported, and reproduced in this work, 1,4-dipolar cycloaddition reactions.

Genetic studies of Russian patients with amyotrophic lateral sclerosis.

Our objective was to search for mutations in genes SOD1, TARDBP, C9orf72, ANG, ATXN2 and VEGF in Russian patients with amyotrophic lateral sclerosis (ALS). A group of 208 Russian patients with ALS was examined. Molecular genetic analysis was conducted using direct sequencing, fragment analysis, and real-time PCR. We found eight different point mutations in the SOD1 gene, with the frequency of mutations being 50% in familial ALS and 3% in sporadic ALS. No mutations were found in exon 6 of the TARDBP gene; however, deletion c.715-126delG in intron 5 of TARDBP was over-represented in ALS patients compared to controls (38% vs. 26.6%; χ(2 )= 13.17; p = 0.002). Hexanucleotide repeat expansion of the C9orf72 gene was revealed in 2.5% of sporadic ALS patients. Mutations in the ANG gene were identified in 1.5% of sporadic ALS patients. The presence of an intermediate number (28-33) of GAC repeats in the ATXN2 gene was observed significantly more often in the study group compared to the control group (5% vs. 1.7%; χ(2 )= 3.89; p = 0.0486). In the cohort examined, we found an association between the disease and the risk A-allele and the A/A genotype at the -2578С/А locus of the VEGF gene. In conclusion, we determined for the first time the genetic basis of ALS in a Russian population.