Polysiloxanes containing thermally stable chiral amide side-chains for capillary gas and supercritical fluid chromatography

Synthesis of Chiral Poly(silyl ether)s via CuH-Catalyzed Asymmetric Hydrosilylation Polymerization of Diketones with Silanes

The precise synthesis of chiral poly(silyl ether)s remains a challenge, in contrast to the well-studied preparation of poly(silyl ether)s. Herein, an unprecedented approach for the synthesis of optically active poly(silyl ether)s with main-chain chirality has been developed via CuH-catalyzed hydrosilylation polymerization of diketones and silanes. The polymerization features low catalyst loading, mild condition, and broad substrate scope, including a wide range of aromatic diketones and heteroaromatic diketones with excellent yields and enantioselectivities (up to 98% yield and 99% ee). Thermal analysis indicated chiral poly(silyl ether)s exhibit good thermal properties. These enantiomerically enriched poly(silyl ether)s with good thermal stability have a promising application in chiral separation.

Electroantennograms by mountain pine beetles,Dendroctonus ponderosae Hopkins, exposed to selected chiral semiochemicals

Electroantennograms (EAGs) were recorded fromD. ponderosae to the enantiomers of the terpenoid bark-beetle pheromonestrans-verbenol,cis-verbenol, verbenone, and the bicyclic ketals frontalin,exo-brevicomin, andendo-brevicomin. Male and female responses to enantiomers of the terpenoids differed significantly only at the two highest concentrations. No sex differences were seen in response to the bicyclic ketals. Significantly different responses to the enantiomers of all the chemicals, except frontalin, were noted over at least part of the dosage-response ranges tested. The negative antipode for all of the terpenoids elicited higher responses, while for the bicyclic ketals, the positive antipode effected the largest responses except for the two highest concentrations ofexo-brevicomin.

Enantioselective measurement of the Candida metabolite D-arabinitol in human serum using multi-dimensional gas chromatography and a new chiral phase

A multi-dimensional gas chromatographic method was developed to measure the Candida metabolite D-arabinitol enantioselectively in human serum. The heptafluorobutyrate derivatives of D-arabinitol, L-arabinitol and ribitol (internal standard) were separated from other serum constituents with a 60 m X 0.32 mm fused-silica SPB-5 precolumn, and (after intermediate cold trapping) they were separated from each other with a 25 m x 0.25 mm fused-silica column coated with a new bonded chiral phase. Replicate analyses of spiked human sera showed that D-arabinitol could be quantified accurately and precisely. The D- and L-arabinitol concentrations in 24 normal adult sera were 0.20 +/- 0.053 and 0.11 +/- 0.040 mu/ml, respectively, and the D- and L-arabinitol/creatinine ratios were 0.023 +/- 0.011 and 0.012 +/- 0.0051, respectively (mean +/- S.D.). In a patient with Candida albicans fungemia, the D-arabinitol/creatinine ratios rose early during infection and fell with successful treatment, whereas L-arabinitol/creatinine ratios did not change significantly. This enantioselective analytical method is more practical than earlier ones; it should facilitate further investigation of D-arabinitol as a diagnostic marker for candidiasis.

Bioanalytical applications of supercritical fluid chromatography

Supercritical fluid chromatography (SFC) has become a valuable tool in analytical chemistry. In the past few years considerable progress has been made in bioanalytical applications of both capillary and packed column SFC. Progress in this respect has especially been made with combined SFC-mass spectrometry, an important alternative to combined liquid chromatography-mass spectrometry. The various applications of capillary and packed column SFC are reviewed, while special attention is given to detection technique applicable in (bioanalytical) SFC. Considerable progress in SFC is expected in the near future.