61 research outputs found
<i>tert</i>-Butyl Sulfoxide as a Starting Point for the Synthesis of Sulfinyl Containing Compounds
Sulfoxides
bearing a <i>tert</i>-butyl group can be activated
using <i>N</i>-bromosuccinimide (NBS) under acidic conditions
and then subsequently treated with a variety of nitrogen, carbon,
or oxygen nucleophiles to afford a wide range of the corresponding
sulfinic acid amides, new sulfoxides, and sulfinic acid esters
Mild and Catalyst-Free Petasis/Decarboxylative Domino Reaction: Chemoselective Synthesis of <i>N</i>âBenzyl Propargylamines
Multicomponent domino reactions are
attractive for assembling functionalized
compounds. To this end, a one-pot catalyst-free chemoselective synthesis
of <i>N</i>-benzyl propargylamines is reported with good
functional group compatibility. This mild process involves <i>in situ</i> formation of an active amine through Petasis reaction
of primary amines, formaldehyde solution, and boronic acids, which
reacts with propiolic acids to give product in up to 94% yield via
decarboxylative coupling reaction
Asymmetric Reduction of <i>tert</i>-Butanesulfinyl Ketimines by NâHeterocyclic Carbene Boranes
N-heterocyclic
carbene borane (NHC-borane) based on a triazole
core is demonstrated for the first time to be efficient for reduction
of a variety of <i>tert</i>-butanesulfinyl ketimines. Up
to 95% yield and up to >99% diastereomeric excess were achieved.
NHC-borane
exhibited excellent activities that are more efficient than or comparable
to commonly used reductive reagents such as NaBH<sub>4</sub>, NaBH<sub>3</sub>CN, l-selectride, Ru catalyst, or BH<sub>3</sub>âTHF
Thermolysis-Induced Two- or Multicomponent Tandem Reactions Involving Isocyanides and Sulfenic-Acid-Generating Sulfoxides: Access to Diverse Sulfur-Containing Functional Scaffolds
Direct
reaction of isocyanides with some sulfenic-acid-generating
sulfoxides led to the effective formation of the corresponding thiocarbamic
acid <i>S</i>-esters in good to high yields. A multicomponent
reaction involving isocyanide, sulfoxide, and a suitable nucleophile
has also been developed, providing ready access to a diverse range
of sulfur-containing compounds, including isothioureas, carbonimidothioic
acid esters, and carboximidothioic acid esters
Synthesis of 3âSubstituted Aryl[4,5]isothiazoles through an All-Heteroatom Wittig-Equivalent Process
Extending
the previous use of <i>tert</i>-butyl sulfoxide
as the sulfinyl source, intramolecular sulfinylation of sulfonamides
was successfully performed. The resulting sulfinimides were not isolated
and instead were believed to go through an all-heteroatom Wittig-equivalent
process to eventually afford arylÂ[4,5]Âisothiazoles in high yields
Unusual Long-Range Ordering Incommensurate Structural Modulations in an Organic Molecular Ferroelectric
The
incommensurate (IC) behaviors of ferroelectrics have been widely investigated
in inorganic oxides as an exciting branch for aperiodic materials,
whereas it still remains a great challenge to achieve such intriguing
effects in organic systems. Here, we present that successive ordering
of dynamic dipoles in an organic molecular ferroelectric, <i>N-</i>isopropylbenzylaminium trichloroacetate (<b>1</b>), enables unusual incommensurately modulated structures between
its paraelectric phase and ferroelectric phase. In particular, <b>1</b> exhibits three distinct IC states coupling with a long-range
ordering modulation. That is, the incommensurately modulated lattice
is âŒ7 times as large as its periodic prototype, and the IC
structure is well solved using a (3 + 1)<i>D</i> superspace
group with the modulated wavevector <b><i>q</i></b> = (0, 0, 0.1589). To the best of our knowledge, <b>1</b> is
the first organic ferroelectric showing such a long-range ordering
IC structural modulation. In addition, structural analyses reveal
that slowing down dynamic motions of anionic moieties accounts for
its modulation behaviors, which also results in dramatic reorientation
of dipolar moments and concrete ferroelectric polarization of <b>1</b> (âŒ0.65 ÎŒC/cm<sup>2</sup>). The combination
of unique IC structural modulations and ferroelectricity makes <b>1</b> a potential candidate for the assembly of an artificially
modulated lattice, which will allow for a deep understanding of the
underlying chemistry and physics of aperiodic materials
Plastic Transition to Switch Nonlinear Optical Properties Showing the Record High Contrast in a Single-Component Molecular Crystal
To
switch bulk nonlinear optical (NLO) effects represents an exciting
new branch of NLO material science, whereas it remains a great challenge
to achieve high contrast for âon/offâ of quadratic NLO
effects in crystalline materials. Here, we report the supereminent
NLO-switching behaviors of a single-component plastic crystal, 2-(hydroxymethyl)-2-nitro-1,3-propanediol
(<b>1</b>), which shows a record high contrast of at least âŒ150,
exceeding all the known crystalline switches. Such a breakthrough
is clearly elucidated from the slowing down of highly isotropic molecular
motions during plastic-to-rigid transition. The deep understanding
of its intrinsic plasticity and superior NLO property allows the construction
of a feasible switching mechanism. As a unique class of substances
with short-range disorder embedded in long-range ordered crystalline
lattice, plastic crystals enable response to external stimuli and
fulfill specific photoelectric functions, which open a newly conceptual
avenue for the designing of new functional materials
One-pot synthesis of α,α-disubstituted Aryl-1-ethanones <i>via</i> the Wittig-Horner reaction
<p></p> <p>A one-pot methodology for the synthesis of α,α-disubstituted aryl-1-ethanones <i>via</i> the Wittig-Horner reaction has been developed and described in this manuscript. Both aryl/alkyl and dialkyl α-branched arylethanone were obtained in high yields (up to 96%) without the use of any metal catalysts. A total of 14 α,α-disubstituted arylethanone derivatives were synthesized based on this simple method that easily converts the carbonyl carbon (sp<sup>2</sup>) into the sp<sup>3</sup> carbon. This versatile method is expected to further promote the use of substituted ketones as synthetic building blocks to construct a variety of α-branched aryl ketones.</p
Construction of Interpenetrated Ruthenium MetalâOrganic Frameworks as Stable Photocatalysts for CO<sub>2</sub> Reduction
Poor stability has long been a major
obstacle to the practical applications of metalâorganic framework
(MOF) photocatalysts. This problem can be overcome by the use of structural
interpenetration. In this work, by modifying Ru metalloligands, we
have rationally designed two Ruâpolypyridine based MOFs (with
non-interpenetrated and interpenetrated structures, respectively),
both of which exhibit similar photocatalytic activities for CO<sub>2</sub> photoreduction. Remarkably, the interpenetrated Ru-MOF possesses
good photocatalytic durability and recyclability, and shows much higher
thermal and photic stability in comparison with its non-interpenetrated
counterpart. To the best of our knowledge, this is the first time
that the stability of MOF photocatalysts was improved by using structural
interpenetration
Microwave-Assisted or CuâNHC-Catalyzed Cycloaddition of Azido-Disubstituted Alkynes: Bifurcation of Reaction Pathways
Microwave
irradiation promoted the intramolecular cycloaddition
of 2-azidoacetamides derived from α-chiral propargylic amines,
affording 1,4,5-trisubstituted triazoles <b>4</b> bearing a
chiral aminomethyl side chain at C5. In contrast, for the same substrates <b>3a</b>â<b>k</b>, CuÂ(I)âNHC complexes catalyzed
the intermolecular cycloaddition in an unexpected desilylative fashion,
leading to 1,4-disubstituted triazoles <b>5</b>. This demonstrates
that 1-silyl alkynes can be employed as substrates for CuAAC with
a suitable coupling partner
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