Crystal and molecular structure of 2-isopropylidene-5-methyl-1,3-dithiolane-1-oxide,C7H12OS2

The acid catalyzed cyclization of 2-propyl(allylthio)sulfine to methyl substituted 2-isopropylidene-1,3-dithiolane-1-oxide occursvia enethiolization of the sulfine followed by an intramolecular addition of thus formed sulfenic acid to the olefinic bond. Crystal data: C₇H₁₂OS₂,M _r=176.3, orthorhombic, space group Pbca,a=9.5551(13),b=17.3407(18),c=10.6417(9)Å,V=1763.2(3)ų,Z=8. The structure was solved by a combination of Patterson and direct methodswR ₂=0.115 for 1554 observations and 106 parameters. The stereochemical relationship between the methyl and sulfoxide oxygen iscis.     

Synthesis of functionalized basketanes by a regiospecific cage expansion of homocubanones

The synthesis of 4-substituted basketanes 11 is realized by a regiospecific one carbon-homologation of the readily available 4-substituted homocubanones 10 Subsequent group transformations, starting from basketanone 4-carboxylic acid 11a, leads to an efficient synthesis of basketane 4-acetates 16.     

Regio- and stereospecific ring-opening reactions of 4-substituted basketanes and seco-basketanes

Homoketonization of basketane acetates6 and 10 on brief treatment with NaOMe in MeOH afforded the seco-basketanones7 and11, respectively, in a stereo-and regiospecific cage opening reaction. As shown by deuterium labeling experiments, both for 6 and 10, this homoketonization proceeds with retention of configuration. Prolonged basic treatment of10 led to the exclusive formation of bicyclo[2.2.2]octenyl-acetates12. Under identical conditions6 produced a complex mixture of products. Upon treatment of seco-basketanones7 and 11 with aq HC1 in MeOH, a rapid regiospecific cationic rearrangement to homobrendanone 14 was observed. This structure was established by X-ray analysis. The effect of a one carbon cage expansion on the base induced cage opening process by extension of the methylene bridge in the homocubane system into an ethylene bridge in the basketane system, is discussed.     

Stereospecific total synthesis of (±) pentenomycins by flash vacuum thermolysis of substituted tricyclo[5.2.1.02,6]decenones

The synthesis of 4-functionalized tricyclo[5.2.1.0^2,6]decenones $\text{9}$, starting from furans, is described. These structures are shown to be suitable precursors for the synthesis of cyclopentenoids such as pentenomycin and analogs.     

ANOVA–principal component analysis and ANOVA–simultaneous component analysis: a comparison

ANOVA–simultaneous component analysis (ASCA) is a recently developed tool to analyze multivariate data. In this paper, we enhance the explorative capability of ASCA by introducing a projection of the observations on the principal component subspace to visualize the variation among the measurements. We compare the significance of experimental effects for ASCA and ANOVA–principal component analysis (PCA), a similar tool to explore multivariate data, by using permutation tests. Furthermore, we quantify the quality of the loadings estimate obtained with ASCA and compare this with the loadings estimate obtained with ANOVA–PCA. Copyright © 2011 John Wiley & Sons, Ltd.     

Sulfur substituted Small-ring Heterocycles

The synthesis of epoxy sulfines and sulfonyl azirines is described