Prins-Friedel-Crafts Cyclization: Synthesis of Diversely Functionalized Six-Membered Oxacycles

2021 ◽  
Vol 25 ◽  
Author(s):  
Snigdha Roy
Keyword(s):  
Subsequent Development ◽  
One Pot ◽  
Cyclization Process ◽  
Carbon Carbon Bond ◽  
Initial Substrate ◽  
Wide Range ◽  
Oxygen Heterocycles ◽  
Carbon Carbon Bonds ◽  
Oxocarbenium Ion ◽  
Proper Modification

: Prins cyclization is a well-established synthetic protocol to generate a wide range of important oxygen heterocycles. It is a cyclization reaction performed by an oxocarbenium ion that undergoes an intramolecular pi-bond attack to construct a new carbon-carbon bond. When this cyclization process is conjugated with Friedel-Crafts reaction, it further expands the synthetic potential by fabricating two different carbon-carbon bonds in one single reaction. Different acid catalysts mediated, the coupled Prins-Friedel-Crafts reaction is conducted both in stepwise as well as in tandem fashion. In the stepwise route, three different reacting components were utilized whereas, the tandem methodology required proper modification of the initial substrate molecule. An array of allylic, propargylic, other related alkenols, and carbonyl reactants were employed to carry out the cyclization process. Several oxygenated heterocycles equipped with diverse functionalities were constructed in a stereoselective manner which again reinforced the significance of this cyclization protocol undoubtedly. The present mini-review highlights (on) the utilization of different one-pot stepwise Prins-Friedel-Crafts reactions and the subsequent development of cascade Prins-Friedel-Crafts cyclization process to furnish intricate molecular architectures of vital six-membered oxacycles.

A review of the composition and evolution of hydrocarbon gases during solidification of the Ilímaussaq alkaline complex, South Greenland

2001 ◽  
pp. 159-166 ◽  
Author(s):  
Jens Konnerup-Madsen
Keyword(s):  
Nepheline Syenite ◽  
Subsequent Development ◽  
High Water ◽  
Vapour Phase ◽  
Low Carbon ◽  
Low Oxygen ◽  
Alkaline Complex ◽  
Hydrocarbon Gases ◽  
Wide Range ◽  
Water Contents

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Konnerup-Madsen, J. (2001). A review of the composition and evolution of hydrocarbon gases during solidification of the Ilímaussaq alkaline complex, South Greenland. Geology of Greenland Survey Bulletin, 190, 159-166. https://doi.org/10.34194/ggub.v190.5187 _______________ Fluid inclusions in minerals from agpaitic nepheline syenites and hydrothermal veins in the Ilímaussaq complex and in similar agpaitic complexes on the Kola Peninsula, Russia, are dominated by hydrocarbon gases (predominantly methane) and hydrogen. Such volatile compositions differ considerably from those of most other igneous rocks and their formation and entrapment in minerals reflects low oxygen fugacities and a wide range of crystallisation temperatures extending to a low-temperature solidus. Their composition reflects initial low carbon contents and high water contents of the magma resulting in the exsolution of a waterrich CO2–H2O dominated vapour phase. Fractionation of chlorides into the vapour phase results in high salinities and the subsequent development of a heterogeneous vapour phase with a highly saline aqueous-rich fraction and a methane-dominated fraction, with preferential entrapment of the latter, possibly due to different wetting characteristics. The light stable isotope compositions support an abiogenic origin for the hydrocarbons in agpaitic nepheline syenite complexes.

Indium Bromide-catalyzed Unprecedented Hydrogenolysis: A Novel One-Pot Synthesis of Per-O-Acetylated β-carboxymethyl O and S-glycosides

2020 ◽  
Vol 24 (8) ◽  
pp. 900-908
Author(s):  
Ram Naresh Yadav ◽  
Amrendra K Singh ◽  
Bimal Banik
Keyword(s):  
Asymmetric Synthesis ◽  
Chiral Auxiliary ◽  
Bioactive Molecules ◽  
One Pot ◽  
Enantiomerically Pure ◽  
Stereoselective Glycosylation ◽  
One Pot Synthesis ◽  
Wide Range

Numerous O (oxa)- and S (thia)-glycosyl esters and their analogous glycosyl acids have been accomplished through stereoselective glycosylation of various peracetylated bromo sugar with benzyl glycolate using InBr3 as a glycosyl promotor followed by in situ hydrogenolysis of resulting glycosyl ester. A tandem glycosylating and hydrogenolytic activity of InBr3 has been successfully investigated in a one-pot procedure. The resulting synthetically valuable and virtually unexplored class of β-CMGL (glycosyl acids) could serve as an excellent potential chiral auxiliary in the asymmetric synthesis of a wide range of enantiomerically pure medicinally prevalent β-lactams and other bioactive molecules of diverse medicinal interest.

Microwave-accelerated Carbon-carbon and Carbon-heteroatom Bond Formation via Multi-component Reactions: A Brief Overview

2020 ◽  
Vol 7 (1) ◽  
pp. 23-39 ◽  
Author(s):  
Kantharaju Kamanna ◽  
Santosh Y. Khatavi
Keyword(s):  
Organic Synthesis ◽  
Bond Formation ◽  
Cycloaddition Reaction ◽  
Nanoparticle Synthesis ◽  
Single Step ◽  
Bioactive Molecules ◽  
One Pot ◽  
Bond Forming ◽  
Material Interest ◽  
Carbon Carbon Bond

Multi-Component Reactions (MCRs) have emerged as an excellent tool in organic chemistry for the synthesis of various bioactive molecules. Among these, one-pot MCRs are included, in which organic reactants react with domino in a single-step process. This has become an alternative platform for the organic chemists, because of their simple operation, less purification methods, no side product and faster reaction time. One of the important applications of the MCRs can be drawn in carbon- carbon (C-C) and carbon-heteroatom (C-X; X = N, O, S) bond formation, which is extensively used by the organic chemists to generate bioactive or useful material synthesis. Some of the key carbon- carbon bond forming reactions are Grignard, Wittig, Enolate alkylation, Aldol, Claisen condensation, Michael and more organic reactions. Alternatively, carbon-heteroatoms containing C-N, C-O, and C-S bond are also found more important and present in various heterocyclic compounds, which are of biological, pharmaceutical, and material interest. Thus, there is a clear scope for the discovery and development of cleaner reaction, faster reaction rate, atom economy and efficient one-pot synthesis for sustainable production of diverse and structurally complex organic molecules. Reactions that required hours to run completely in a conventional method can now be carried out within minutes. Thus, the application of microwave (MW) radiation in organic synthesis has become more promising considerable amount in resource-friendly and eco-friendly processes. The technique of microwaveassisted organic synthesis (MAOS) has successfully been employed in various material syntheses, such as transition metal-catalyzed cross-coupling, dipolar cycloaddition reaction, biomolecule synthesis, polymer formation, and the nanoparticle synthesis. The application of the microwave-technique in carbon-carbon and carbon-heteroatom bond formations via MCRs with major reported literature examples are discussed in this review.

Nickel-Catalyzed Electronically-Reversed Enantioselective Hydrocarbofunctionalizations of Acrylamides

Synlett ◽  
2021 ◽  
Author(s):  
Lou Shi ◽  
Wei Shu
Keyword(s):  
Nickel Catalyst ◽  
Functional Group ◽  
Optically Active ◽  
Forming Process ◽  
Carbon Bond ◽  
Bond Forming ◽  
Synthetic Strategy ◽  
Carbon Carbon Bond ◽  
Wide Range ◽  
Simple Protocol

Asymmetric hydrocarbofunctionalizations of alkenes has emerged as an efficient synthetic strategy for accessing optically active molecules via carbon-carbon bond-forming process from readily available alkenes and carbo-electrophiles. Herein, we present a summary of the efforts from our group to control the regio- and enantioselectivity of hydrocarbofunctionalizations of electron-deficient alkenes with a nickel catalyst and chiral bisoxazolidine ligand. The reaction undergoes electron-reversed hydrocarbofunctionalizations acrylamides with excellent enantioselectivity. This operationally simple protocol enables the asymmetric hydroalkylation, hydrobenzylation and hydropropargylation of acrylamides. This reaction is useful for preparing a wide range of α-branched chiral amides with broad functional group tolerance.

scholarly journals Single particle dual plasmonic effect for efficient organic solar cells

2021 ◽  
Author(s):  
Adi Prasetio ◽  
Soyeon Kim ◽  
Muhammad Jahandar ◽  
Dong Chan Lim
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Light Absorption ◽  
Resonance Effect ◽  
Localized Surface Plasmon ◽  
Main Role ◽  
Charge Generation ◽  
One Pot ◽  
Wide Range ◽  
Light Reflectance

AbstractIncorporating localized surface plasmon resonance (LSPR) into organic solar cells (OSCs) is a popular method for improving the power conversion efficiency (PCE) by introducing better light absorption. In this work, we designed a one-pot synthesis of Ag@SiO2@AuNPs dual plasmons and observed an immense increase in light absorption over a wide range of wavelengths. Ag@SiO2 plays the main role in enhancing light absorption near the ultraviolet band. The silica shell can also further enhance the LSP resonance effect and prevent recombination on the surface of AgNPs. The AuNPs on the Ag@SiO2 shell exhibited strong broad visible-light absorption due to LSP resonance and decreased light reflectance. By utilizing Ag@SiO2@AuNPs, we could enhance the light absorption and photoinduced charge generation, thereby increasing the device PCE to 8.57% and Jsc to 17.67 mA cm−2, which can be attributed to the enhanced optical properties. Meanwhile, devices without LSPR nanoparticles and Ag@SiO2 LSPR only showed PCEs of 7.36% and 8.18%, respectively.

scholarly journals Determinants of vitamin D status in Kenyan calves

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Rebecca Callaby ◽  
Emma Hurst ◽  
Ian Handel ◽  
Phil Toye ◽  
Barend M. de C. Bronsvoort ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Vitamin D ◽  
Health Outcomes ◽  
Critical Role ◽  
Subsequent Development ◽  
Vitamin D Metabolites ◽  
Vitamin D Status ◽  
Skeletal Health ◽  
A Genome ◽  
Wide Range

AbstractVitamin D plays a critical role in calcium homeostasis and in the maintenance and development of skeletal health. Vitamin D status has increasingly been linked to non-skeletal health outcomes such as all-cause mortality, infectious diseases and reproductive outcomes in both humans and veterinary species. We have previously demonstrated a relationship between vitamin D status, assessed by the measurement of serum concentrations of the major vitamin D metabolite 25 hydroxyvitamin D (25(OH)D), and a wide range of non-skeletal health outcomes in companion and wild animals. The aims of this study were to define the host and environmental factors associated with vitamin D status in a cohort of 527 calves from Western Kenya which were part of the Infectious Disease of East African Livestock (IDEAL) cohort. A secondary aim was to explore the relationship between serum 25(OH)D concentrations measured in 7-day old calves and subsequent health outcomes over the following 12 months. A genome wide association study demonstrated that both dietary and endogenously produced vitamin D metabolites were under polygenic control in African calves. In addition, we found that neonatal vitamin D status was not predictive of the subsequent development of an infectious disease event or mortality over the 12 month follow up period.

Mechanistic Study on Gold(I)-Catalyzed Unsaturated Spiroketalization Reaction

2022 ◽  
Vol 19 ◽  
Author(s):  
Kamlesh Sharma
Keyword(s):  
Activation Barrier ◽  
Ring Formation ◽  
Hydroxyl Group ◽  
Mechanistic Study ◽  
Protecting Group ◽  
Wide Range ◽  
Oxocarbenium Ion ◽  
Metal Catalyzed ◽  
Insight Into ◽  
Mechanism Of The Reaction

Abstract: The mechanism of metal-catalyzed spiroketalization of propargyl acetonide is explored by employing DFT with the B3LYP/6-31+G(d) method. Acetonide is used as a regioselective regulator in the formation of monounsaturated spiroketal. The energies of transition states, intermediates, reactants and products are calculated to provide new insight into the mechanism of the reaction. The energetic features, validation of the observed trends in regioselectivity are conferred in terms of electronic indices via FMO analysis. The presence of acetonide facilitates a stepwise spiroketalization as it masks the competing nucleophile, and thus hydroxyl group present, exclusively acts as a nucleophile. The vinyl gold intermediate 3 is formed from 2 via activation barrier TS1. This is the first ring formation, which is 6-exo-dig cyclization. The intermediate 3 is converted into allenyl ether 4, which isomerizes to the intermediate oxocarbenium ion 5 via activation barrier TS2. The intermediate 5 cyclizes to 6 via TS3. This is the second ring formation. The intermediate 6 on protodeauration turns into 6,6-monounsaturated spiroketal 7. It is concluded that acetonide as a protecting group serves the purpose, and thus a wide range of spiroketals can be prepared, regioselectivity.

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