Gold-Catalyzed Cascade Reaction of Diynamides with Allylic Alcohols: A Versatile Platform to Allenamide, 2-Aminofuran and Bridged [2.2.2]Octadiene Derivatives.

Transition metal-catalyzed divergent synthesis through alternation of the catalyst is appealing, as it provides an operationally simple way to access different valuable products, while using the same reactants as starting materials. Herein, a gold-catalyzed cascade reaction of conjugated diynamides with allylic alcohols is described. By variation of the catalysts, substituted allenes and furans could be obtained selectively. Mechanistic studies indicate that, after the addition of allylic alcohol to gold-activated diynamide, a [3,3]-sigmatropic rearrangement would take place and lead to the formation of a common reactive intermediate, which would further convert to the final products selectively. Further variation of the structure of diynamides has unveiled an additional reaction sequence involving intramolecular Himbert arene/allene Diels-Alder cycloaddition to afford a series of dearomatized products bearing bicyclo[2,2,2]octadiene core.

Efficient access to 1,3,4-trisubstituted pyrroles via gold-catalysed cycloisomerization of 1,5-diynes.

A gold-catalysed cycloisomerization of 1,5-diynes is described, which offers a selective approach to access 1,3,4-trisubstituted pyrroles. In this reaction, the cationic gold catalyst activates the ynamide moiety, initiating the cycloisomerization to produce the pyrrole core, and H2O acts as an external nucleophile to trap the vinyl cationic species, thus leading to the formation of 1,3,4-trisubstituted pyrroles with high selectivity.

Genetic variability of human papillomavirus type 51 E6, E7, L1 and L2 genes in Southwest China.

Genetic variations among HR-HPV types lead to altered biological functions with possible clinical significance in different geographical locations. To explore intratype genetic variations of HPV51 E6, E7, L1 and L2 genes originating from Southwest China, a total of 5204 cervical scraped cell samples were collected for DNA extraction and HPV typing. And then the E6, E7, L1 and L2 genes of HPV51 (n = 79) were sequenced and compared to the reference sequence (M62877). The ConSurf server was used for identification of conserved structural and functional amino acids of the E6 and E7 oncogenes, and the changes of the secondary structure were analyzed by PSIPred software. Phylogenetic trees were constructed by the maximum likelihood method implemented in IQ-TREE. The selection pressure acting on the E6, E7, L1 and L2 genes was estimated by Datamonkey web server. 13 nucleotide polymorphism sites were observed in E6-E7 gene and the most common mutation sites were C395T (S100L), C756T (S66L), C796T, A832G. 36 nucleotide polymorphism sites were identified in full length L1 gene and the non-synonymous mutations T6311G, A6312T (V264G), G6313A (G265S) A5674C (I52L), A6335C (N272T), A6586C (T354P) and synonymous mutations A5649T, C6147T, A6435G, G6570A, A6651G, T6774C, A6784C, A6882G, C6918A, and G6984A were the most common mutations. 53 nucleotide variation sites were identified in full-length L2 gene including four insertion sites (4418A, 4670G, 4693A, 4694C) and one deletion site (A4430). Besides, the non-synonymous mutations G4227A (V32I), A4407G (I92V), G4945A (D271N), C4985A (T284K), T5260G (L376V), A5335C (T401P) and the synonymous mutations A4166G, G4229A, G4283A, T4453C, C4566A, T4596C, C4695T, C4830T, G4839A, A5160C, and T5286G were the most common mutations. Specially, a triallelic mutation site (G4461C/A) in L2 was identified, with 26% G4461C (E109D) being non-synonymous mutation. Selective pressure analysis showed that only codon site 66 in E7 and 52 in L1 were the positively selected sites and codon sites 72, 107, 342, 412, 427 were negatively selected sites in L2 gene. Our investigation also suggests that A2 and A4 were the most frequent HPV51 lineage in Southwest China.

Genetic variability and lineage phylogeny of human papillomavirus type 45 based on E6 and E7 genes in Southwest China.

The current study investigated nucleotide variability and phylogeny in high-risk HPV45 collected from Chinese women. Fifty-one samples positive for single infections of HPV45 were collected for DNA extraction and HPV typing. The E6 and E7 genes of HPV45 were sequenced, and then the phylogenetic tree was reconstructed by the maximum likelihood method implemented in IQ-TREE under the HKY nucleotide substitution model. The selection pressures of the E6 and E7 genes were estimated using PAML software. Eleven nucleotide polymorphism sites were observed in the HPV45 E6 sequences, with 6 synonymous (C134T, T163C, A284C, T341C, T482C, A497G) and 5 non-synonymous (A124C, C157T, T162A, G259T, G487A) mutations. Six nucleotide polymorphism sites were observed in the E7 sequences, with 5 non-synonymous (G600A, A603C, A769C, G808T, G832T) and 1 synonymous (A718C) mutation. Our investigation suggests that B2 was the most frequent HPV45 sublineage in Southwest China, followed by A2; no A1 or A3 variants were detected. Selective pressure analysis showed that these mutations could reflect positive selection in HPV45 E6 and E7 genes.