Asymmetric transformation requires the use of chiral catalysts which is hampered by energy intensive processes such as high cost, inefficient recycle, and tedious separation. Here we report the use of single‐layered, chiral porous sheets with induced pore chirality for repeatable asymmetric transformation and self‐separation without the need of chiral catalysts or chiral auxiliaries. The asymmetric induction is driven by chiral fixation of absorbed achiral substrates inside the chiral pores to transform...
Tue Sep 01, 2020 20:02
Smart molecular crystals with light‐driven mechanical responses have received intense interest owing to their potential uses in developing novel molecular machines, artificial muscles, and biomimetics. However, challenges remain in control over both the dynamic photo‐mechanical behaviors and static photonic properties of molecular crystals that are based on the same molecule. Herein, we illustrate that the construction of isostructural co‐crystals is an effective approach to tune on/off their light‐induced...
Tue Sep 01, 2020 19:27
The catalytic asymmetric synthesis of the anti‐COVID‐19 drug remdesivir has been realized via the coupling of the P‐racemic phosphoryl chloride with protected nucleoside GS441524. The chiral bicyclic imidazole catalyst is crucial for the dynamic kinetic asymmetric transformation (DyKAT) to proceed smoothly with high reactivity and excellent stereoselectivity [96% conv., 22:1 P(S):P(R)]. Mechanistic studies showed that this DyKAT is a first‐order visual kinetic reaction dependent on catalyst concentration....
Tue Sep 01, 2020 18:04
All‐cis 1,2,4,5‐tetrakis (trifluoromethyl)‐ and all‐cis 1,2,3,4,5,6‐hexakis (trifluoromethyl)‐ cyclohexanes were prepared by direct aryl hydrogenation. All‐cis 1,2,3,4,5,6‐hexakis(trifluoromethyl)cyclohexane has a high barrier to ring inversion (ΔG≠=27 kcal mol−1) and a Janus face profile with a large diffuse negative density on the fluorine face, and a focused positive density on the hydrogen face which coordinates carbonyls and halides. Abstract We report the synthesis of all‐cis 1,2,4,5‐tetrakis...
Tue Sep 01, 2020 17:59
Cu surface sites coordinated to N‐heterocyclic carbenes are distinguished between silica‐supported Cu nanoparticles and single sites by solid‐state NMR spectroscopy and computation. The distinct signatures correlate with distinct activities, only the nanoparticles catalyzing alkyne semihydrogenation. The molecular‐level description of supported nanoparticles illustrates how surface chemistry can bind surface science with heterogeneous catalysis. Abstract Supported metal nanoparticles are...
Tue Sep 01, 2020 17:58
[4+2] Cross‐cycloadditions between uracil‐based aldehydes and β‐aryl enals were carried out under mild reaction conditions in the presence of the popular diphenylsilyl‐protected prolinol organocatalyst, which provided homo‐synergistic activation of both substrates. Bicyclic and tricyclic fused uracils were chemodivergently forged in good yields with maximum levels of enantioselectivity. Abstract The discovery of chemical methods enabling the construction of carbocycle‐fused uracils which...
Tue Sep 01, 2020 17:58
Described is a metal‐free C−H allylation to access a wide range of functionalized ortho‐allyl‐iodoarenes. The method employs (diacetoxy)iodoarene precursors and proceeds through the iodane‐guided “iodonio‐Claisen” allyl transfer using allylsilanes. The reaction proceeds through an in‐plane aromatic cyclic transition state, and it was used in the concise synthesis of the experimental antimitotic agent Dosabulin. EWG=electron‐withdrawing group. Abstract A metal‐free C−H allylation strategy...
Tue Sep 01, 2020 17:57
The synergistic combination of photoredox and transition metal catalysis enables the installation of C(sp3)‐hybridized centers under exceedingly low energy barriers, rendering this platform a formidable tool in synthetic applications. To fully harness this mode of catalysis, considerable efforts have been devoted toward stereoselective transformations. This Minireview discusses milestones to accomplish and understand the origin of stereoinduction in these processes. Abstract Metallaphotoredox...
Tue Sep 01, 2020 17:55
Cross and linearly conjugated largely π‐extended multichromophoric molecules have been prepared through incorporating both porphyrins and pentacenequinone/pentacene in one molecule. These multichromophoric molecular systems displayed interesting structure–property relationships. Linearly conjugated bisporphyrin‐pentacene molecules showed unusual stability. Abstract A series of largely π‐extended multichromophoric molecules including cross‐conjugated, half cross‐conjugated, conjugation‐interrupted...
Tue Sep 01, 2020 17:55
A platinum‐catalyzed enyne cycloisomerization reaction to construct the bicyclo[3.1.0]hexane system enabled the total synthesis of cryptotrione from commercially available homoveratric acid in a diastereoselective and diastereodivergent manner (see scheme). This strategy would be practical for synthesizing other members of the structurally unprecedented cryptotrione family. Abstract The total synthesis of cryptotrione (1) was enabled by substrate‐controlled diastereoselective construction...
Tue Sep 01, 2020 17:55
Biomass‐derived materials photoconvert biomass: A triple natural resource system is reported that uses solar energy to convert biomass from untreated water into sustainable H2 and organics. The process is photocatalyzed by scalable carbon dots produced from α‐cellulose that act as water‐soluble light absorbers to photoconvert lignocellulose with a Ni cocatalyst. The carbon dots function under ambient conditions and benign aqueous solution. Abstract A sunlight‐powered process is reported...
Tue Sep 01, 2020 17:54
An interfacial microreactor was developed to accelerate electrochemical reactions (see picture). Voltage‐controlled acceleration of electrochemical reactions was possible through voltage‐dependent formation of the interfacial microreactor. The electrochemical microreactor can be used for on‐demand electrochemical derivatization and the in situ mechanistic study of electrochemical reactions. Abstract Microdroplet chemistry is attracting increasing attention for accelerated reactions at the...
Tue Sep 01, 2020 17:52
Melding norbornyl (NB) into π‐conjugated skeletons can not only strengthen intermolecular π‐π interaction but also offer stronger nonbonding effect, thus boosting ISC and suppressing nonradiative loss dramatically, thereby invoke stronger and more persistent room‐temperature phosphorescence (RTP). The unexpected convergence of RTP and photochromism also provides a unique platform to explore the inherent photophysical processes. Abstract Herein, norbornyl (NB), a bulky annular nonconjugated...
Tue Sep 01, 2020 17:52
A series of porphyrinic multivariate metal–organic frameworks (MTV‐MOFs) were pyrolyzed to generate a range of single‐atom metals implanted in N‐doped carbon (M1‐N‐C; M=Fe, Co, Ni and Cu). The M1‐N‐C model catalysts, with an almost identical carbon support environment, demonstrated different activities toward CO2 electroreduction. The best performer, Ni1‐N‐C, achieved highly selective reduction of CO2 even at low pressures. Abstract Single‐atom catalysts (SACs) are of great interest because...
Tue Sep 01, 2020 17:52
Photoredox and NHC catalysis in concert: A novel strategy for the preparation of β‐trifluoromethylketones via radical alkene acyltrifluoromethylation has been developed. The three‐component cascades proceed under mild conditions with readily available aroyl fluorides, styrenes and the Langlois reagent as the reaction partners. Abstract Despite the great potential of radical chemistry in organic synthesis, N‐heterocyclic carbene (NHC)‐catalyzed reactions involving radical intermediates are...
Tue Sep 01, 2020 17:50
A crystalline metal–peptide pore entraps chiral alcohols and ketones in a single‐crystal‐to‐single‐crystal manner. Crystallographic analyses revealed their chemical structures, chiral conformations, and even an unstable equilibrium product. Abstract Porous metal complexes enable single‐crystal X‐ray crystallographic observation of included guests or reaction intermediates through simple soaking with the guests/substrates. Previous studies on this technique have often encountered difficulties...
Tue Sep 01, 2020 17:50
The transition‐metal‐free cross‐coupling of alkyl or aryl electrophiles using tertiary benzylic organoboronates is reported. This reaction involves the generation of tertiary alkyl anions from organoboronates in the presence of an alkoxide base and then their substitution reactions. This protocol allows the simple and efficient construction of quaternary carbon centers.
Tue Sep 01, 2020 13:55
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