A borylative exo-cyclization of alkenyl halides has been reported. The reaction includes the regioselective addition a borylcopper(I) intermediate to unactivated terminal alkenes, followed by intramolecular substitution resulting alkylcopper(I) moiety for halide leaving groups. Experimental and theoretical investigations mechanism have also described. This provides new method synthesis alkylboronates containing strained cycloalkyl structures from simple starting materials.

Enantioselective 1,1-diarylation of terminal alkenes enabled by the combination Pd catalysis with a chiral anion phase transfer (CAPT) strategy is reported herein. The reaction substituted benzyl acrylates aryldiazonium salts and arylboronic acids gave corresponding 3,3-diarylpropanoates in moderate to good yields high enantioselectivies (up 98:2 er). Substituents on acrylate CAPT catalyst significantly affect enantioselectivity, multidimensional parametrization identified correlations...

An unexpected borylation of organic halides with a silyborane in the presence an alkoxy base has been observed. This formal nucleophilic boryl substitution can be applied to broad range substrates high functional group compatibility. Even sterically hindered aryl bromides afforded corresponding compounds yields. Preliminary mechanistic studies indicated that this is promoted by neither transition-metal contamination nor radical-mediated process.

A mechanistic study of the Pd-catalyzed enantioselective 1,1-diarylation benzyl acrylates that is facilitated by a chiral anion phase transfer (CAPT) process presented. Kinetic analysis, labeling, competition, and nonlinear effect experiments confirm hypothesized general mechanism reveal role phosphate counterion in CAPT catalysis. The was found to be involved step stereoinduction process, as expected, but also unproductive reaction provides traditional Heck byproduct. Multivariate...

A new method has been developed for the catalytic asymmetric synthesis of α-chiral linear or carbocyclic (γ-alkoxyallyl)boronates via copper(I)-catalyzed γ-boryl substitution allyl acetals. This reaction afforded products in high yields with excellent E:Z selectivities and enantioselectivities [only (E)-product, 91-98% ee] also exhibited functional group compatibility. Subsequent allylation aldehydes provided anti-1,2-diol derivatives a highly stereospecific manner, utility was further...

The first catalytic enantioselective nucleophilic borylation of a C═O double bond has been achieved. A series aldehydes reacted with diboron reagent in the presence copper(I)/DTBM-SEGPHOS complex catalyst using MeOH as proton source to give corresponding optically active α-alkoxyorganoboronate esters excellent enantioselectivities. Furthermore, products could be readily converted functionalized chiral alcohol derivatives through stereospecific C–C forming reactions involving stereogenic C–B bond.

The regio- and diastereoselective silaboration of aromatic alkenes with a silylboron compound proceeds in the presence catalytic amount potassium tert-butoxide, providing complementary method to corresponding transition metal-catalyzed reactions.

Theoretical and experimental studies have been conducted to elucidate the mechanism of formal nucleophilic boryl substitution aryl alkyl bromides with silylborane in presence potassium methoxide. Density functional theory was used conjunction artificial force induced reaction method current study determine this reaction. The results analysis led identification a unique carbanion-mediated involving halogenophilic attack silyl nucleophile on bromine atom substrate. These calculations have,...

A transition-metal-free method has been developed for the boryl substitution of functionalized aryl-, heteroaryl- and alkenyl halides with a silylborane in presence an alkali-metal alkoxide. The base-mediated organohalides was recently reported to provide corresponding borylated products good high yields, exhibit functional group compatibility tolerance steric hindrance. In this study, scope transformation extended significantly include wide variety halides. particular, (

In the last 10 years, extensive earthquake swarms have occurred intermittently in region east of Izu Peninsula, central Japan. July 1989 an active swarm again took place off Ito City, and among all past activities, it was nearest to land shallowest. This activity eventually became a weak submarine eruption, first its kind this region. Associated with event, borehole tiltmeter at 92 m depth, installed several kilometers from source area, detected distinct continuous tilt change following...

Stereoselective silicon-tethered alkylboration of alkynes in the presence a copper(I) catalyst and diboron reagent provided corresponding cyclic alkenylboronates high yields (up to 99% yield) with excellent regio- syn-selectivities (E/Z = <1:99). The products, which can be considered as formal alkyne intermolecular undergo subsequent selective derivatization, including ring opening, give functionalized trans-stilbene derivatives.

Abstract An asymmetric monoborylation of alkenylsilanes catalyzed by a copper(I) complex with the chiral bisphosphine ligand BenzP* is reported. The reaction proceeded excellent regioselectivity and high enantioselectivity to afford corresponding optically active organoboronate esters stereogenic CB bond containing vicinal silyl group. synthetic utility product demonstrated through stepwise transformations multifunctional compounds in stereospecific manner. magnified image

The Miyakejima observation network had been constructed by the National Research Institute for Earth Science and Disaster Prevention mainly until early 1999. This has provided crustal deformation data tiltmeters GPS seismic short-period broadband seismometers in association with 2000 eruption. subsurface magma movement at first stage of present activity, during period from June 26 to 27, was successfully detected tilt measurements. change observed five stations indicates migration magmas...

The carbon–halogen bond-selective borylation of alkyl halides bearing terminal CC double bonds has been achieved using a copper(<sc>i</sc>) catalyst. This reaction represents useful complementary approach to conventional procedures for the borylative cyclization reported in our previous work.

The 2000 eruptive activity of Miyakejima island began with an earthquake swarm and crustal deformation that was clearly observed by continuous observations ground tilt GPS on Miyakejima. Based the data, we estimated magma migration process at initial stage (18:30 LT June 26–06:00 27) activity. in has been characterized a collapse-caldera formation no fissure eruption flank island, which is markedly different from style recent eruptions 1940, 1962 1983. We constructed source model...

Hydrolytic enantioselective protonation of dienyl esters and a β-diketone catalyzed by phase-transfer catalysts are described. The latter reaction is the first example an enantio-convergent retro-Claisen condensation. Corresponding various optically active α,β-unsaturated ketones having tertiary chiral centers adjacent to carbonyl groups were obtained in good excellent yields enantiomeric ratios (83–99%, up 97.5:2.5 er).

New, bulky tris(trimethylsilyl)silylboronate pinacol and hexylene glycol esters ((TMS)3Si–B(pin) (TMS)3Si–B(hg)) were prepared in 46 61% yields, respectively, by the reaction of tris(trimethylsilyl)silylpotassium with corresponding boron electrophiles. Notably, these silylboronate exhibited high stability to air silica gel applied transition-metal-free boryl substitution aryl halides, providing desired borylated products yields excellent B:Si ratios (up 96% yield, B/Si = 99/1). These new...

Abstract Highly efficient Wacker oxidation of aromatic or aliphatic terminal alkenes into methyl ketones and benzofurans is developed by using reusable Pd 0 nanoparticles (NPs) supported on ZrO 2 under acid‐ cocatalyst‐free conditions. Molecular oxygen air can be utilized as the oxidant, which results in formation H O only theoretical byproduct. The activation NPs plays an important role promoting this reaction. Interestingly, PdO showed no activity. Additionally, particle size significantly...

Like an enzyme: Asymmetric hydrolysis of enol esters is accomplished by chiral phase-transfer catalysts under biphasic base conditions. Stoichiometric reactions support the generation a well-organized ammonium hydroxide species (Q+OH−). Detailed facts importance to specialist readers are published as ”Supporting Information”. Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted authors. Please note: The publisher responsible for content functionality...

Asymmetric base hydrolysis of α-chiral esters with synthetic small-molecule catalysts is described. Quaternary ammonium salts derived from quinine were used as chiral phase-transfer to promote the N-protected amino acid hexafluoroisopropyl in a CHCl3/NaOH (aq) via dynamic kinetic resolution, providing corresponding products moderate good yields (up 99%) up 96:4 er. Experimental and computational mechanistic studies using DFT calculation pseudotransition state (pseudo-TS) conformational...

In July 1989, an extensive earthquake swarm took place off Ito City, eastern Izu Peninsula, central Japan. It was nearest to land and shallowestamong the persistent swarms repeated in this region last 10 years. This activity eventually became a weak submarine eruption, thefirstofitskind region. Associated with event, plenty of crustal movement data were obtained by various institutions. Basedonthesedatacombinedwith seismic data, we constructed dislocation model interpret seismo-volcanic...

Step‐like tilt changes were observed at intervals of dozens hours during the caldera formation stage occurred 2000 Miyakejima volcano eruption. Our analysis suggests that these steps caused by cyclic expansion a subsurface sill‐like magma plumbing system trending from SE to NW volcano. In same period gradually grew summit area very large 1.6 km in diameter and 450 m depth. The source mechanism is fairly well explained two‐phase flow instability, called pressure drop oscillation. This model...

Bacteroides thetaiotaomicron VPI-5482 harbors a gene encoding putative cycloisomaltooligosaccharide glucanotransferase (BT3087) belonging to glycoside hydrolase family 66. The goal of the present study was characterize catalytic properties this enzyme. Therefore, we expressed BT3087 (recombinant endo-dextranase from VPI-5482) in Escherichia coli and determined that recombinant preferentially synthesized isomaltotetraose isomaltooligosaccharides (degree polymerization > 4) dextran. enzyme...