This review provides an overview of synthetic transformations that have been performed by both electro- and photoredox catalysis. Both toolboxes are evaluated and compared in their ability to enable ...said transformations. Analogies and distinctions are formulated to obtain a better understanding in both research areas. This knowledge can be used to conceptualize new methodological strategies for either of both approaches starting from the other. It was attempted to extract key components that can be used as guidelines to refine, complement and innovate these two disciplines of organic synthesis.
Ball milling is a simple, fast, cost-effective green technology with enormous potential. One of the most interesting applications of this technology in the field of cellulose is the preparation and ...the chemical modification of cellulose nanocrystals and nanofibers. Although a number of studies have been reported in the literature, the potential of this technique in the field of cellulose nanoparticles has not been fully exploited. This minireview aims at putting existing work into perspective, highlighting the significance and the potential of this green, sustainable technique to facilitate the identification of areas of future development.
Ball milling, an efficient method to obtain cellulose nanofibers and nanocrystals.
An intermolecular coupling of primary alcohols and organotriflates has been developed to provide ketones by the action of a Ni(0) catalyst. This oxidative transformation is proposed to occur by the ...union of three distinct catalytic cycles. Two competitive oxidation processes generate aldehyde in situ via hydrogen transfer oxidation or (pseudo)dehalogenation pathways. As aldehyde forms, a Ni-catalyzed carbonyl-Heck process enables formation of the key carbon–carbon bond. The utility of this rare alcohol to ketone transformation is demonstrated through the synthesis of diverse complex and bioactive molecules.
Pentafluorosulfanyl (SF5)‐containing compounds and corresponding analogs are a highly valuable class of fluorine‐containing building blocks owing to their unique properties. The reason for that is ...the set of peculiar and tremendously beneficial characteristics they can impart on molecules once introduced onto them. Despite this, their application in distinct scientific fields remains modest, given the extremely harsh reaction conditions needed to access such compounds. The recent synthetic approaches via S−F, and C−SF5 bond formation as well as the use of SF5‐containing building blocks embody a “stairway‐to‐heaven” loophole in the synthesis of otherwise‐inaccessible chemical scaffolds only a few years ago. Herein, we report and evaluate the properties of the SF5 group and analogs, by summarizing synthetic methodologies available to access them as well as following applications in material science and medicinal chemistry since 2015.
SF6 building blocks: This review article summarizes the recent synthetic methodology dedicated to pentafluorosulfanyl derivatives and their related analogs. The properties and up‐to‐date applications in materials sciences and medicinal chemistry of SF5‐containing compounds are also discussed here.
Contrast-enhanced computed tomography offers a nondestructive approach to studying adipose tissue in 3D. Several contrast-enhancing staining agents (CESAs) have been explored, whereof osmium ...tetroxide (OsO4) is the most popular nowadays. However, due to the toxicity and volatility of the conventional OsO4, alternative CESAs with similar staining properties were desired. Hf-WD 1:2 POM and Hexabrix have proven effective for structural analysis of adipocytes using contrast-enhanced computed tomography but fail to provide chemical information. This study introduces isotonic Lugol’s iodine (IL) as an alternative CESA for adipose tissue analysis, comparing its staining potential with Hf-WD 1:2 POM and Hexabrix in murine caudal vertebrae and bovine muscle tissue strips. Single and sequential staining protocols were compared to assess the maximization of information extraction from each sample. The study investigated interactions, distribution, and reactivity of iodine species towards biomolecules using simplified model systems and assesses the potential of the CESA to provide chemical information. (Bio)chemical analyses on whole tissues revealed that differences in adipocyte gray values post-IL staining were associated with chemical distinctions between bovine muscle tissue and murine caudal vertebrae. More specific, a difference in the degree of unsaturation of fatty acids was identified as a likely contributor, though not the sole determinant of gray value differences. This research sheds light on the potential of IL as a CESA, offering both structural and chemical insights into adipose tissue composition.
A convenient transformation of phenols into the corresponding aryl fluorosulfates is presented: the first protocol to completely circumvent direct handling of gaseous sulfuryl fluoride (SO2F2). The ...proposed method employs 1,1′-sulfonyldiimidazole as a precursor to generate near-stoichiometric amounts of SO2F2 gas using a two-chamber reactor. With NMR studies, it was shown that this ex situ gas evolution is extremely rapid, and a variety of phenols and hydroxylated heteroarenes were fluorosulfated in good to excellent yields.
A palladium‐catalyzed carbonylative approach for the direct conversion of (hetero)aryl bromides into their α,α‐bis(trifluoromethyl)carbinols is described, and it employs only stoichiometric amounts ...of carbon monoxide and trifluoromethyltrimethylsilane. In addition, aryl fluorosulfates proved highly compatible with these reaction conditions. The method is tolerant of a diverse set of functional groups, and it is adaptable to late‐stage carbon‐isotope labeling.
The more the merrier: Described is the direct synthesis of aryl bis(trifluoromethyl)carbinols from aryl bromides and fluorosulfates with a stoichiometric amount of carbon monoxide and two equivalents of trifluoromethyltrimethylsilane. The method exhibits good yields, broad scope, and good functional‐group tolerance, and is suitable for carbon‐isotope labeling.
Sulfur(VI) Fluoride Exchange (SuFEx) chemistry stands as a well-established method for swiftly constructing complex molecules in a modular fashion. An especially promising segment of this toolbox is ...reserved for multidimensional SuFEx hubs: three or more substituents pluggable into a singular S
centre to make 'beyond-linear' clicked constructions. Sulfurimidoyl difluorides (RNSOF
) stand out as the prime example of this, however their preparation from the scarcely available thionyl tetrafluoride (SOF
) limits this chemistry to only a few laboratories with access to this gas. In this work, we identify silver pentafluorooxosulfate (AgOSF
) as a viable SuFEx hub with reactivity equal to SOF
. The AgF
-mediated oxidation of SOCl
gives rise to the hexacoordinate AgOSF
adduct, which in contact with primary amines produces the sulfurimidoyl fluorides in high yields. In addition, we have found this workflow to be fully extendable to the trifluoromethyl homologue, AgOSF
CF
, and we propose the use of AgOSF
X salts as a general route to azasulfur SuFEx electrophiles from commercial starting materials.
Sulfur(VI) Fluoride Exchange (SuFEx) chemistry stands as a well‐established method for swiftly constructing complex molecules in a modular fashion. An especially promising segment of this toolbox is ...reserved for multidimensional SuFEx hubs: three or more substituents pluggable into a singular SVI centre to make ‘beyond‐linear’ clicked constructions. Sulfurimidoyl difluorides (RNSOF2) stand out as the prime example of this, however their preparation from the scarcely available thionyl tetrafluoride (SOF4) limits this chemistry to only a few laboratories with access to this gas. In this work, we identify silver pentafluorooxosulfate (AgOSF5) as a viable SuFEx hub with reactivity equal to SOF4. The AgF2‐mediated oxidation of SOCl2 gives rise to the hexacoordinate AgOSF5 adduct, which in contact with primary amines produces the sulfurimidoyl fluorides in high yields. In addition, we have found this workflow to be fully extendable to the trifluoromethyl homologue, AgOSF4CF3, and we propose the use of AgOSF4X salts as a general route to azasulfur SuFEx electrophiles from commercial starting materials.
Sulfurimidoyl difluorides (RNSOF2) are excellent multidimensional SuFEx hubs, however their preparation from the scarcely available thionyl tetrafluoride (SOF4) gas limits this chemistry. Here, we propose silver pentafluorooxosulfate (AgOSF5) as a viable alternative to SOF4. Prepared by the AgF2‐mediated oxidation of SOCl2, we found that the adduct produces sulfurimidoyl fluorides in high yields from primary amines, also extendable to AgOSF4CF3.
This study presents a synthesis of 4H‐1,2,3triazolo1,5‐aindol‐4‐ones. The key step in the synthesis of this new heterocyclic scaffold is an intramolecular cyclization via an unprecedented ...carbonylative C–H functionalization of 1‐(2‐bromoaryl)‐1,2,3‐triazoles. Isotopic labelling of the carbonyl carbon atom is possible using near stoichiometric amounts of 13CO. Additionally, an alternative pathway via carbonylative Sonogashira coupling followed by a two‐step, one‐pot azidation/cycloaddition is also investigated, giving rise to the same scaffold.
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