27 research outputs found
Thermal Mitigation at User Equipment Based on Ambient Temperature
User equipment (UE) or other user devices employ thermal mitigation schemes that are responsive to the ambient temperature of the device. Such schemes can employ different levels or modes of thermal mitigation techniques based on ambient temperature, the thresholds that trigger the switch between levels or modes may be scaled based on ambient temperature, or a combination thereof
Six-membered ring systems: with O and/or S atoms
A large variety of publications involving O- and S-6-membered ring systems
have appeared in 2017. The importance of these heterocyclic compounds
is highlighted by the huge number of publications on the total
synthesis of natural oxygen derivatives and of other communications
dedicated to synthetic derivatives.
Reviews on stereoselective organocatalytic synthesis of tetrahydropyrans
(17EJO4666), of tetrahydropyrans and their application in total synthesis of
natural products (17CSR1661), on the synthesis of the less thermodynamically
stable 2,6-trans-tetrahydropyrans (17S4899), on enantioselective
synthesis of polyfunctionalized pyran and chromene derivatives
(17TA1462), and on enantioselective and racemic total synthesis of
camptothecins, including the formation of their pyran-2-one ring
(17SL1134), have appeared.
Advances in the transition metal-catalyzed synthesis of pyran-2/4-ones
(17TL263), N-heterocyclic carbene (NHC)-catalyzed achiral synthesis of
pyran-2-one, coumarin and (thio)chromone derivatives (17OBC4731), on
the synthesis and transformation of 2H-pyran-2-ones (17T2529) and
2-styrylchromones (17EJO3115) into other heterocyclic compounds, have
been surveyed. The strategies to build up the tetrahydropyranyl core of
brevisamide (17H(95)81) and the reactions of ketyl radicals, generated from
carbonyl derivatives under transition-metal photoredox-catalyzed conditions,
leading to isochromen- and chroman-type compounds (17CC13093) were
disclosed. Developments in the synthesis of pentafluorosulfanyl(chromene
and coumarin) derivatives (17TL4803), photoswitchable D9-tetrahydrocannabinol
derivatives (17JA18206), and aminobenzopyranoxanthenes
with nitrogen-containing rings (17JOC13626) have been studied.info:eu-repo/semantics/publishedVersio
Metal- and O<sub>2</sub>‑Free Oxidative C–C Bond Cleavage of Aromatic Aldehydes
An
oxidative C–C cleavage of aldehydes requiring neither
metals nor O<sub>2</sub> was discovered. Homobenzylic aldehydes and
α-substituted homobenzylic aldehydes were cleaved to benzylic
aldehydes and ketones, respectively, using nitrosobenzene as an oxidant.
This reaction is chemoselective for aromatic aldehydes, as an aliphatic
aldehyde was unreactive under these conditions, and other reactive
functionality such as ketones and free alcohols are tolerated. A mechanism
accounting for the fate of the lost carbon is proposed
Synthesis of Spirooxindoles via the <i>tert</i>-Amino Effect
A new
method is developed
for the synthesis of spirooxindoles from amines and isatins via C–H
functionalization. The reaction leverages the <i>tert</i>-amino effect to form an enolate–iminium intermediate via
[1,5]-hydride shift followed by cyclization. Interestingly the hydride
migrates to the N atom of a Cî—»N, which is atypical for hydride
additions to imines
FeCl<sub>3</sub>‑Catalyzed Allylation Reactions onto 3‑Hydroxy-2-oxindoles: Formal Total Syntheses of Bis-cyclotryptamine Alkaloids, (±)-Chimonanthine, and (±)-Folicanthine
An FeCl<sub>3</sub>-catalyzed efficient strategy for the allylation
reactions of 3-hydroxy-2-oxindoles with allyltrimethylsilane has been
developed. The reaction affords a variety of 2-oxindoles having quaternary
center at the pseudobenzylic position in an operationally simple and
inexpensive procedure. Control experiments using enantioenriched 3-hydroxy-2-oxindole
show that the reaction proceeds through in situ generated 2<i>H</i>-indol-2-one (<b>8</b>). The methodology presents
an efficient and concise access to the pyrroloindoline alkaloids (±)-deoxyeseroline
(<b>1a</b>), (±)-esermethole (<b>1b</b>), (±)-physostigmine
(<b>1c</b>), (±)-phenserine (<b>1d</b>), and (±)-physovenine
(<b>1e</b>). Eventually, we extrapolated the scope of this methodology
to the formal total syntheses of dimeric cyclotyrptamine alkaloids
(±)-chimonanthine (<b>3a</b>), (±)-folicanthine (<b>3c</b>), and (±)-calycanthine (<b>4</b>)
FeCl<sub>3</sub>‑Catalyzed Allylation Reactions onto 3‑Hydroxy-2-oxindoles: Formal Total Syntheses of Bis-cyclotryptamine Alkaloids, (±)-Chimonanthine, and (±)-Folicanthine
An FeCl<sub>3</sub>-catalyzed efficient strategy for the allylation
reactions of 3-hydroxy-2-oxindoles with allyltrimethylsilane has been
developed. The reaction affords a variety of 2-oxindoles having quaternary
center at the pseudobenzylic position in an operationally simple and
inexpensive procedure. Control experiments using enantioenriched 3-hydroxy-2-oxindole
show that the reaction proceeds through in situ generated 2<i>H</i>-indol-2-one (<b>8</b>). The methodology presents
an efficient and concise access to the pyrroloindoline alkaloids (±)-deoxyeseroline
(<b>1a</b>), (±)-esermethole (<b>1b</b>), (±)-physostigmine
(<b>1c</b>), (±)-phenserine (<b>1d</b>), and (±)-physovenine
(<b>1e</b>). Eventually, we extrapolated the scope of this methodology
to the formal total syntheses of dimeric cyclotyrptamine alkaloids
(±)-chimonanthine (<b>3a</b>), (±)-folicanthine (<b>3c</b>), and (±)-calycanthine (<b>4</b>)