scholarly journals Selective Dealkenylative Functionalization of Styrenes via C-C Bond Cleavage

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jianzhong Liu ◽  
Jun Pan ◽  
Xiao Luo ◽  
Xu Qiu ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Double Bond ◽  
Late Stage ◽  
Bond Cleavage ◽  
Fine Chemicals ◽  
The Novel ◽  
Single Bond ◽  
The Past ◽  
Aryl Amines ◽  
Site Selective ◽  
Important Building Block

As a readily available feedstock, styrene with about 25 million tons of global annual production serves as an important building block and organic synthon for the synthesis of fine chemicals, polystyrene plastics, and elastomers. Thus, in the past decades, many direct transformations of this costless styrene feedstock were disclosed for the preparation of high-value chemicals, which to date, generally performed on the functionalization of styrenes through the allylic C-H bond, C(sp2)-H bond, or the C=C double bond cleavage. However, the dealkenylative functionalization of styrenes via the direct C-C single bond cleavage is so far challenging and still unknown. Herein, we report the novel and efficient C-C amination and hydroxylation reactions of styrenes for the synthesis of valuable aryl amines and phenols via the site-selective C(Ar)-C(alkenyl) single bond cleavage. This chemistry unlocks the new transformation and application of the styrene feedstock and provides an efficient protocol for the late-stage modification of substituted styrenes with the site-directed dealkenylative amination and hydroxylation.

scholarly journals σ-Bond Hydroboration of Cyclopropanes

2020 ◽  
Author(s):  
Hiroki Kondo ◽  
Shin Miyamura ◽  
Chisa Kobayashi ◽  
Arifin ◽  
Stephan Irle ◽  
...  
Keyword(s):  
Double Bond ◽  
Natural Product ◽  
Organic Synthesis ◽  
Bond Cleavage ◽  
Cross Coupling ◽  
High Reactivity ◽  
Natural Product Synthesis ◽  
Theoretical Studies ◽  
Single Bond

Hydroboration of alkenes is a classical reaction in organic synthesis, in which alkenes react with boranes to give alkylboranes, with subsequent oxidation resulting in alcohols. The double bond (π-bond) of alkenes can be readily reacted with boranes owing to its high reactivity. However, the single bond (σ-bond) of alkanes has never been reacted. To pursue the development of σ-bond cleavage, we selected cyclopropanes as model substrates since they present a relatively weak σ-bond. Herein, we describe an iridium-catalyzed hydroboration of cyclopropanes, resulting in β-methyl alkylboronates. These unusually branched boronates can be derivatized by oxidation or cross-coupling chemistry, accessing “designer” products that are desired by practitioners of natural product synthesis and medicinal chemistry. Furthermore, mechanistic investigations and theoretical studies revealed the enabling role of the catalyst.

Recent Advances in Organic Synthesis Based on N,N-Dimethyl Enaminones

Synthesis ◽  
2020 ◽  
Author(s):  
Fuchao Yu ◽  
Jiuzhong Huang
Keyword(s):  
Double Bond ◽  
Organic Synthesis ◽  
Bond Cleavage ◽  
Building Blocks ◽  
Chemical Transformations ◽  
Methyl Ketones ◽  
Comprehensive Overview ◽  
The Past ◽  
Leaving Group ◽  
Group A

AbstractEnaminones are gaining increasing interest because of their unique properties and their importance in organic synthesis as versatile building blocks. N,N-Dimethyl enaminones offer a better leaving group (a dimethylamine group) than other enaminones, and allow further elaboration via a range of facile chemical transformations. Over the past five years, there have been an increasing number of reports describing the synthetic applications of N,N-dimethyl enaminones. This review provides a comprehensive overview on the synthetic applications of N,N-dimethyl enaminones that have been reported since 2016.1 Introduction2 Direct C(sp2)–H α-Functionalization2.1 Synthesis of α-Sulfenylated N,N-Dimethyl Enaminones2.2 Synthesis of α-Thiocyanated N,N-Dimethyl Enaminones2.3 Synthesis of α-Acyloxylated N,N-Dimethyl Enaminones3 Functionalization Reactions via C=C Double Bond Cleavage3.1 Synthesis of Functionalized Methyl Ketones3.2 Synthesis of α-Ketoamides, α-Ketoesters and 1,2-Diketones3.3 Synthesis of N-Sulfonyl Amidines4 Construction of All-Carbon Aromatic Scaffolds4.1 Synthesis of Benzaldehydes4.2 Synthesis of the Naphthalenes5 Construction of Heterocyclic Scaffolds5.1 Synthesis of Five-Membered Heterocycles5.2 Synthesis of Six-Membered Heterocycles5.3 Synthesis of Quinolines 5.4 Synthesis of Functionalized Chromones5.5 Synthesis of Other Fused Polycyclic Heterocycles6 Conclusions and Perspectives

Apparent carbon–carbon bond cleavage in an epoxide. 2,3,4,5,6-Hexachloro-12-oxopentacyclo[5.4.1.1.8,11.03,10.05,9]tridecane; a minor product from the acid treatment of endrin

1982 ◽  
Vol 60 (4) ◽  
pp. 501-508 ◽  
Author(s):  
John W. ApSimon ◽  
Kazu Yamasaki ◽  
Alain Fruchier ◽  
Alfred S. Chau ◽  
Carol P. Huber
Keyword(s):  
Sulfuric Acid ◽  
Double Bond ◽  
Acid Treatment ◽  
Bond Cleavage ◽  
Single Bond ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Parameters ◽  
Carbon Carbon Bond ◽  
A Minor

The treatment of endrin (1) with sulfuric acid produces ketoendrin 2 and from 6 to 8% of another product that we show to be 2,3,4,4,5,6-hexachloro-12-oxapentacyclo[5.4.1.1.8,11.03,10.05,9]tridecane 3, based initially on spectral evidence and confirmed by a single crystal X-ray diffraction study. The formation of 3 involves an apparent and unusual carbon–carbon single bond cleavage in an epoxide accompanied by cycloaddition to a proximate carbon–carbon double bond. This transformation probably proceeds by the route outlined in ref. 1. Some of the observed nmr parameters of 3 are discussed in the light of its structure and a comparison is made with the observed spectra for endrin (1).

Catalyst-free photoinduced selective oxidative C(sp3)–C(sp3) bond cleavage in arylamines

2021 ◽  
Author(s):  
Jingwei Zhou ◽  
Songping Wang ◽  
Wentao Duan ◽  
Qi Lian ◽  
Wentao Wei
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Bond Cleavage ◽  
Oxidative Cleavage ◽  
Light Irradiation ◽  
Single Bond ◽  
Catalyst Free ◽  
Site Selective

By introducing a polar atom at the γ-position of amine, the site-selective oxidative cleavage of the saturated C–C single bond in arylamines can be easily achieved by simple visible light irradiation with O2 as a benign oxidant and catalyst free.

Hydraulic Laboratory at University of Liège

2018 ◽  
pp. 80-89
Author(s):  
Willi H. Hager
Keyword(s):  
Basic Research ◽  
The Novel ◽  
University Campus ◽  
Current Position ◽  
Professional Background ◽  
The Past ◽  
Comprehensive Picture

The Hydraulic Laboratory of Liège University, Belgium, is historically considered from its foundation in 1937 to the mid-1960s. The technical facilities of the various Buildings are highlighted, along with canals and instrumentation available. It is noted that in its initial era, comparatively few basic research has been conducted, mainly due to the professional background of the professors leading the establishment. This state was improved in the past 50 years, however, particularly since the Laboratory was dislocated to its current position in the novel University Campus. Biographies of the leading persons associated with the Liège Hydraulic Laboratory are also presented, so that a comprehensive picture is given of one of the currently leading hydraulic Laboratories of Europe.

The Pornographer and McGahern's Allusive Practice

2017 ◽  
Vol 47 (2) ◽  
pp. 281-297
Author(s):  
Tom Walker
Keyword(s):  
Social Practice ◽  
Literary Tradition ◽  
The Novel ◽  
Present Value ◽  
The Past

Allusions to other texts abound in John McGahern's fiction. His works repeatedly, though diffidently, refer to literary tradition. Yet the nature of such allusiveness is still unclear. This article focuses on how allusion in The Pornographer (1979) is depicted as an intellectual and social practice, embodying particular attitudes towards the function of texts and the knowledge they represent. Moreover, the critique of the practice of allusion that the novel undertakes is shown to have broader significance in terms of McGahern's whole oeuvre and its evolving attempts to salvage something of present value from the literature of the past.

A Review on Fast Dissolving Tablet

2017 ◽  
Vol 8 (03) ◽  
Author(s):  
Sagar T. Malsane ◽  
Smita S. Aher ◽  
R. B. Saudagar
Keyword(s):  
Drug Delivery ◽  
Patient Compliance ◽  
Research Area ◽  
Oral Route ◽  
Dosage Forms ◽  
The Novel ◽  
The Past ◽  
Orally Disintegrating Tablets ◽  
Novel Drug ◽  
Experience Difficulty

Oral route is presently the gold standard in the pharmaceutical industry where it is regarded as the safest, most economical and most convenient method of drug delivery resulting in highest patient compliance. Over the past three decades, orally disintegrating tablets (FDTs) have gained considerable attention due to patient compliance. Usually, elderly people experience difficulty in swallowing the conventional dosage forms like tablets, capsules, solutions and suspensions because of tremors of extremities and dysphagia. In some cases such as motion sickness, sudden episodes of allergic attack or coughing, and an unavailability of water, swallowing conventional tablets may be difficult. One such problem can be solved in the novel drug delivery system by formulating “Fast dissolving tablets” (FDTs) which disintegrates or dissolves rapidly without water within few seconds in the mouth due to the action of superdisintegrant or maximizing pore structure in the formulation. The review describes the various formulation aspects, superdisintegrants employed and technologies developed for FDTs, along with various excipients, evaluation tests, marketed formulation and drugs used in this research area.

Oleanolic Acid Derived from Plants: Synthesis and Pharmacological Properties of A-ring Modified Derivatives

2020 ◽  
Vol 17 (9) ◽  
pp. 1084-1101
Author(s):  
Tingjuan Wu ◽  
Xu Yao ◽  
Guan Wang ◽  
Xiaohe Liu ◽  
Hongfei Chen ◽  
...  
Keyword(s):  
Drug Design ◽  
Oleanolic Acid ◽  
Water Solubility ◽  
Future Application ◽  
The Novel ◽  
Pharmacological Effects ◽  
Framework Structure ◽  
Design And Synthesis ◽  
The Past ◽  
The Relationship

Background: Oleanolic Acid (OA) is a ubiquitous product of triterpenoid compounds. Due to its inexpensive availability, unique bioactivities, pharmacological effects and non-toxic properties, OA has attracted tremendous interest in the field of drug design and synthesis. Furthermore, many OA derivatives have been developed for ameliorating the poor water solubility and bioavailability. Objective: Over the past few decades, various modifications of the OA framework structure have led to the observation of enhancement in bioactivity. Herein, we focused on the synthesis and medicinal performance of OA derivatives modified on A-ring. Moreover, we clarified the relationship between structures and activities of OA derivatives with different functional groups in A-ring. The future application of OA in the field of drug design and development also was discussed and inferred. Conclusion: This review concluded the novel achievements that could add paramount information to the further study of OA-based drugs.

scholarly journals Novel late-stage radiosynthesis of 5-[18F]-trifluoromethyl-1,2,4-oxadiazole (TFMO) containing molecules for PET imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nashaat Turkman ◽  
Daxing Liu ◽  
Isabella Pirola
Keyword(s):  
Late Stage ◽  
Histone Deacetylases ◽  
Radiochemical Purity ◽  
Radiochemical Yield ◽  
Single Step ◽  
The Novel ◽  
Molar Activity ◽  
The Central Nervous System ◽  
Class Iia Hdacs ◽  
18F Fluoride

AbstractSmall molecules that contain the (TFMO) moiety were reported to specifically inhibit the class-IIa histone deacetylases (HDACs), an important target in cancer and the disorders of the central nervous system (CNS). However, radiolabeling methods to incorporate the [18F]fluoride into the TFMO moiety are lacking. Herein, we report a novel late-stage incorporation of [18F]fluoride into the TFMO moiety in a single radiochemical step. In this approach the bromodifluoromethyl-1,2,4-oxadiazole was converted into [18F]TFMO via no-carrier-added bromine-[18F]fluoride exchange in a single step, thus producing the PET tracers with acceptable radiochemical yield (3–5%), high radiochemical purity (> 98%) and moderate molar activity of 0.33–0.49 GBq/umol (8.9–13.4 mCi/umol). We validated the utility of the novel radiochemical design by the radiosynthesis of [18F]TMP195, which is a known TFMO containing potent inhibitor of class-IIa HDACs.

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