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Both products of the kinetic resolution were used in the resolution/recombination approach shown in the scheme for the enantioselective total synthesis of (−)-octalactin A. Bn=benzyl, TBS=tert-butyldimethylsilyl. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z800554_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
Objective. Pre‐sleep cognitive activity has been implicated in the maintenance of sleep‐onset insomnia. The present study aimed to investigate the focus of attention, content and characteristics of cognition during the pre‐sleep period. Method. A semi‐structured clinician‐administered interview designed to index the content of pre‐sleep cognition was completed by individuals diagnosed with sleeponset insomnia ( N = 30) and good sleepers ( N = 30). Result. The pre‐sleep cognitive activity of insomniacs could be distinguished from that of good sleepers by being more focused on worries, problems and noises in the environment, and less focused on ‘nothing in particular’. In terms of content, the insomnia group were more likely to think about not sleeping or about something that had happened during the day. Insomniacs experienced their presleep cognitive activity as more occupying, less intentional, for a longer duration, and as causing more difficulty with sleep onset compared to good sleepers. Pre‐sleep imagery was reported at similar rates across diagnosis, but was more distressing and more likely to be associated with strong physical sensations for the insomniac group compared with the good sleeper group. Conclusion. The present study provides a comprehensive investigation of presleep cognitive activity and raises a number of areas for future research including monitoring of bodily sensations, imagery, problem‐solving and non‐active strategies in facilitating sleep onset.
Fusion constructs as protein overexpression vectors proved to be critical in the heterologous expression of terpene synthases in cyanobacteria. The concept was recently applied to the heterologous overexpression of the β-phellandrene synthase (β- PHLS) from plants, fused to the highly expressed endogenous cpcB gene encoding the β-subunit of phycocyanin. Overexpressed CpcB*PHLS fusion proteins enhanced the heterologous yield of C<sub>10</sub>H<sub>16</sub> β-phellandrene hydrocarbons production in Synechocystis. This work extended the concept of fusion constructs as protein overexpression vectors by showing that highly expressed heterologous genes could also serve as leader sequences for protein overexpression in cyanobacteria. Examined are the kanamycin nptI and chloramphenicol cmR resistance cassettes, both of which are overexpressed in Synechocystis. Evidence showed a dual purpose of the nptI gene, as a leader sequence fused to a heterologous geranyl-diphosphate synthase ( GPPS), promoting its expression, while at the same time serving as a selectable marker for the screening of transformants. The work further showed that enhanced GPPS expression increased the yield of β-phellandrene in Synechocystis transformants harboring the β- PHLS gene. Moreover, the research evaluated the expression efficacy of a DNA fragment comprising 87 nucleotides from the 5' end of the cmR gene in fusion with the GPPS gene. This short fusion construct substantially increased the intracellular geranyl-diphosphate synthase level, suggesting that "short-stretch" cmR leader sequences can be used to drive a higher expression level of heterologous biosynthetic genes, while avoiding undesirable internal recombinations, as these sequences are shorter than the threshold of 200 bp, commonly assumed to be the threshold of high efficiency recombinations.
A family of water-soluble, negative-tone, high-resolution, chemically amplified photoresists based on partially or fully deprotected poly(1,2:5,6-di-O-isopropylidene-3-O-methacryloyl-α-d-glucofuranose) is described. Both the molecular weight of the parent ketal-protected polymer and the extent of its deprotection to a water-soluble polymer containing 3-O-methacryloyl-d-glucopyranose repeat units must be carefully controlled to provide good coating and imaging properties. The two ketal protecting groups of the poly(1,2:5,6-di-O-isopropylidene-α-d-glucofuranose) have different reactivity, and their complete removal requires long reaction times under hydrolytic conditions. The detailed deprotection chemistry of the polymer is readily understood through model studies with the fully and partially protected analogues of the polymer pendant groups: 1,2:5,6-di-O-isopropylidene-α-d-glucofuranose and 1,2-isopropylidene-α-d-glucopyranose. When combined with a water-soluble photochemical precursor of acid such as (4-methoxyphenyl)dimethylsulfonium trifluoromethanesulfonate, films of the deprotected or partially deprotected poly(1,2:5,6-di-O-isopropylidene-3-O-methacryloyl-α-d-glucofuranose) undergo acid-catalyzed cross-linking. The enhanced performance of the partially deprotected polymers over that of poly(3-O-methacryloyl-d-glucopyranose) suggests that the presence of remaining hydrophobic groups that afford water dispersibility rather than full solubility may be key to their performance. Imaged negative-tone features as small as 0.2 μm are obtained with these materials that have sensitivities of ca. 30 mJ/cm2 with wholly aqueous casting and processing.
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This is a very nice follow-up paper to a previously reported kinetic resolution ofα-hydroxy esters by Toste and co-workers (J. Am. Chem. Soc. 2005, 127, 1090-1091). A variety of enantioenriched tetrahydrofurans and tetrahydropyrans can be accessed by this method. High diastereoselectivities and enantioselectivies were obtained through careful optimization of the conditions. Acetone was found to be the solvent of choice, giving the best yields of the desired products.
