Chromium-catalyzed olefination of arylaldehydes with haloforms assisted by 2,3,5,6-tetramethyl-,'-bis(trimethylsilyl)-1,4-dihydropyrazine.

Chromium-catalyzed olefination of arylaldehydes with haloforms was achieved using 2,3,5,6-tetramethyl-,'-bis(trimethylsilyl)-1,4-dihydropyrazine (1a) as an organic reducing agent, giving β-halostyrene derivatives in a -selective manner. The reaction required no metal powders, such as zinc and manganese, as reductants, thereby minimizing metal-based reaction waste.

Safety of early rehabilitation in patients with aneurysmal subarachnoid hemorrhage: A retrospective cohort study.

Objective: To investigate the safety and efficacy of early rehabilitation in patients with aneurysmal subarachnoid hemorrhage (aSAH) patients.

Methods: One hundred eleven patients with aSAH admitted between April 2015 and March 2019, were retrospectively evaluated. The early rehabilitation program was introduced in April 2017 to actively promote mobilization and walking training for aSAH patients.

Preparation of Functionalized Amides Using Dicarbamoylzincs.

We report a new convenient preparation of dicarbamoylzincs of type (R R NCO) Zn by the treatment of ZnCl and formamides R R NCHO with LiTMP in THF (15 °C, 15 min) or by the reaction of formamides R R NCHO with TMP Zn (25 °C, 16 h). This second method tolerates sensitive groups such as an ester, ketone or nitro function. Reaction of these dicarbamoylzincs with allylic, benzylic, aryl, alkenyl bromides, acid chlorides, aldehydes or enones provided various polyfunctional amides in 47-97 % yields.

Direct Synthesis of Indoles from Azoarenes and Ketones with Bis(neopentylglycolato)diboron Using 4,4'-Bipyridyl as an Organocatalyst.

Multifunctionalized indole derivatives were prepared by reducing azoarenes in the presence of ketones and bis(neopentylglycolato)diboron (Bnep) with a catalytic amount of 4,4'-bipyridyl under neutral reaction conditions, where 4,4'-bipyridyl acted as an organocatalyst to activate the B-B bond of Bnep and form ,'-diboryl-1,2-diarylhydrazines as key intermediates. Further reaction of ,'-diboryl-1,2-diarylhydrazines with ketones afforded -vinyl-1,2-diarylhydrazines, which rearranged to the corresponding indoles via the Fischer indole mechanism. This organocatalytic system was applied to diverse alkyl cyclic ketones, dialkyl, and alkyl/aryl ketones, including heteroatoms.

Metal-Free Deoxygenation and Reductive Disilylation of Nitroarenes by Organosilicon Reducing Reagents.

A metal-free deoxygenation and reductive disilylation of nitroarenes was achieved using N,N'-bis(trimethylsilyl)-4,4'-bipyridinylidene (1) under mild and neutral reaction conditions, and a broad functional group tolerance was possible in this reaction. Mono-deoxygenation, giving a synthetically valuable N,O-bis(trimethylsilyl)phenylhydroxylamine (7 a) as a readily available and safe phenylnitrene source from nitrobenzene, and double-deoxygenation, giving N,N-bis(trimethylsilyl)anilines 8, were easily controlled by varying the amounts of 1 and reaction temperature as well as adding dibenzothiophene (DBTP). Reaction of 2-arylnitrobenzenes with 1 resulted in the formation of the corresponding carbazoles 14 via in situ-generated phenylnitrene species derived by thermolysis of N,O-bis(trimethylsilyl)phenylhydroxylamines 7, followed by their subsequent intramolecular C-H insertion.

Metathesis cleavage of an N[double bond, length as m-dash]N bond in benzo[c]cinnolines and azobenzenes by triply-bonded ditungsten complexes.

A metathesis reaction of a W[triple bond, length as m-dash]W bond and an N[double bond, length as m-dash]N bond was observed by reacting a W-W triply-bonded W(iii)2 complex, (tBuO)3W[triple bond, length as m-dash]W(OtBu)3 (1), with benzo[c]cinnoline derivatives to form biphenyl-linked dinuclear (imido)tungsten complexes 2-4. When azobenzene was used as the substrate, a trans to cis isomerization induced by blue-LED light was essential prior to the metathesis cleavage of the N[double bond, length as m-dash]N bond by the W[triple bond, length as m-dash]W bond of (Me2N)2(TfO)W[triple bond, length as m-dash]W(OTf)(NMe2)2 (6), affording the corresponding imido-bridged dinuclear tungsten complexes 7-9.

A reversible strain-induced electrical conductivity in cup-stacked carbon nanotubes.

We have used in situ current-voltage measurements of cup-stacked carbon nanotubes (CSCNTs) to establish reversible strain induced (compressive bending) semiconducting to metallic behavior. The corresponding electrical resistance decreases by two orders of magnitude during the process, and reaches values comparable to those of highly crystalline multi-walled carbon nanotubes (MWCNTs) and graphite. Joule heating experiments on the same CSCNTs showed that the edges of individual cups merge to form "loops" induced by the heating process.