Mesoionische Sechsringheterocyclen, III Reaktionen o-chinoider Verbindungen mit 6-Oxo-6H-1,3-diazin-1-ium-4-olaten

Mesoionische 6-Oxo-6H-1,3-diazin-1-ium-4-olate 9 reagieren mit Tetrachlor-o-benzochinon (2, R = Cl) unter Bildung von 1:1-Addukten 12, die sich formal von den Ketentautomeren 13 von 9 ableiten. Die Struktur von 12f wurde durch eine Röntgenstrukturanalyse geklärt

2-Thiabicyclo[3.2.0]hepta-3,6-Dienes. 3. Desulfuration and Sulfuration of 2-Thiabicyclo[3.2.0]hepta-3,6-Dienes and X-Ray Crystal Structure of 3a,6,7,8,9,9a-Hexahydro-3a,5-Dimethylthieno[3,2-B][2]benzothiophene-2,3-Dicarbonitrile

The 2-3.2.0] hepta-3,6-Dienes 1–7 Extrude Sulfur in Solution at 285 °C to Give the 1,2-Benzenedicarbonitriles 8–12 in Yields of 42–56%. 5-(1,1-Dimethylethyl)-3,6-Dimethyl-2-3.2.0] hepta-3,6-Diene-1,7-Dicarbonitrile (6) Reacts at 140 °C to Give a Mixture of the Cope-Rearranged Isomer 13, the 1,2-Benzenedicarbonitrile 11, and possibly a 3a,6a-Dihydrothieno[3,2-B] thiophene (14). Reaction of 2a,5,6,7,8,8a-Hexahydro-2a,4-Dimethylbenzo[C]cyclobuta[B]thiophene-L,2-Dicarbonitrile (15) at 140 °C Gives a Mixture of De8ulfurated (16) and Sulfureted (17) Products in Yields of 88% and 70%, Respectively. Single-Crystal X-Ray Analysis Proved the 3a,6,7,8,9,9a-Hexahydrothieno[3,2-B][2]benzothiophene Structure (17). the Possible Mechanism of the Insertion of Sulfur in the Carbon-Carbon Single Bond of 15 is Discussed. © 1982, American Chemical Society. All Rights Reserved

Supramolecular materials: molecular packing of tetranitrotetrapropoxycalix[4]arene in highly stable films with second-order nonlinear optical properties

Highly stable films of tetranitrotetrapropoxycalix[4]arene (9) with second-order nonlinear optical (NLO) properties and a noncentrosymmetric structure were obtained by a novel crystallization process at 130-140 degrees C in a de electric field. The packing of 9 in these films was elucidated by a combination of X-ray diffraction, angle-dependent second- harmonic generation, and scanning force microscopy (SFM). The experimental results agree well with solid-state molecular dynamics calculations for these films. No crystalline phase was observed for nitrocalix[4]arene derivatives with longer or branched alkyl chains; this explains the limited NLO stability of films of these calixarenes. Scanning force microscopy o­n the aligned films of 9 showed two distinct surface lattice structures: a rectangular lattice (a = 9.3, b = 11.7 Angstrom) and a pseudohexagonal lattice (d approximate to 11.4 Angstrom). The combination of these data with the interlayer distance of 8.9 Angstrom (X-ray diffraction) allowed the packing of molecules of 9 in these structures to be fully elucidated at the molecular level

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Isolation and X-ray crystal structure of a stable calix[4]arene monohemiketal

The formation of a stable calix[4]arene monohemiketal is described. X-ray crystallographic data provide conclusive evidence for the presence of a stabilizing hydrogen bon