The chemical behavior of lithium silenolates,
(Me3Si)2SiC(OLi)R (1a,
R = Mes; 1b, R =
t-Bu), toward carbonyl compounds was studied. Treatment
of lithium silenolates 1a and
1b with benzaldehyde and then with chlorotriethylsilane
afforded products derived from
the reactions of the lithium silenolates with 2 equiv of benzaldehyde,
followed by coupling
of the resulting anions with chlorotriethylsilane, in good yields.
Treatment of 1a and 1b
with mesityl aldehyde under the same conditions proceeded similarly to
give the respective
adducts in high yields, while the reaction of 1a with
acetophenone gave the adduct only in
low yield. Similar reactions of 1a and 1b
with mesityl methyl ketone, however, afforded no
adducts but produced lithium 1-mesitylethenolate and the respective
acylbis(trimethylsilyl)silanes.
The purpose of this study was to compare the concentration of trace elements in the
plasma of sea turtles that inhabited the suburban (Okinawa Main Island, n=8) and the rural
coast (Yaeyama Island, n=57) in Okinawa, Japan. Particle induced X-ray emission allowed
detection of 20 trace and major elements. The wild sea turtles in the suburban coast in
Okinawa were found to have high concentrations of Pb, Si and Ti in the plasma when
compared to the rural area but there were no significant changes in the Al, As and Hg
concentrations. These results may help to suggest the status of some elements in a marine
environment. Further, monitoring the plasma trace and major element status in sea turtles
can be used as a bio-monitoring approach by which specific types of elements found here
could indicate effects that are related to human activities.
The chemical properties of lithium silenolates toward dienes were
studied. The reaction
of lithium
2-tert-butyl-1,1-bis(trimethylsilyl)silen-2-olate
(1a) with butadiene at −40 °C,
followed by hydrolysis, afforded
2-tert-butyl-1,1-bis(trimethylsilyl)silacyclohex-4-en-2-ol,
derived from [2 + 4] cycloaddition of 1a with butadiene,
in 94% yield. Similar treatment of
lithium 2-adamantyl-1,1-bis(trimethylsilyl)silen-2-olate
(1b) gave the respective adduct in
87% yield. The reactions of lithium silenolates
1a,b with 2,3-dimethylbutadiene,
isoprene,
and 1,3-pentadiene proceeded in a fashion similar to those with
butadiene to give the [2 +
4] cycloadducts in high yields. The reactions of
1a,b with 2,3-dimethylbutadiene and
butadiene at room temperature gave the products originated from
1,1-bis(trimethylsilyl)silacyclohexa-1,4-diene intermediates. The crystal structure of
10-adamantyl-2,3,6,7-tetramethyl-9-(trimethylsilyl)-9-silabicyclo[4.4.0]deca-2,6-diene
(6b), which was obtained from the
reaction of 1b with 2,3-dimethylbutadiene at room
temperature, was determined by a single-crystal X-ray diffraction study.
To encourage and guide antimicrobial stewardship team (AST) activity and promote appropriate antibiotic use, we studied the impact of day of the week on the initiation and discontinuation of antibiotic administration. This was a multicenter observational study conducted at 8 Japanese hospitals from April 1 to September 30, 2019, targeting patients who underwent treatment with broad-spectrum antibiotics, such as anti-methicillin-resistant Staphylococcus aureus agents and anti-pseudomonal agents. We compared the weekly numbers of initiations and discontinuations of antibiotic prescription on each day of the week or on the days after a holiday. There was no statistical difference in the number of antibiotic initiations on both weekdays and the day after a holiday. However, antibiotic discontinuation was significantly higher from Tuesday onward than Monday and from the second day than the first day after a holiday. Similar trends were observed regardless of the categories of antibiotics, hospital and admission ward, and AST activity. This study suggests that broad-spectrum antibiotics tend to be continued during weekends and holidays and are most likely to be discontinued on Tuesday or the second day after a holiday. This was probably due to behavioral factors beyond medical indications, requiring further antimicrobial stewardship efforts in the future.
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