[2+1] Cycloadditions of Diazoalkanes to Enol Ethers Catalyzed by Chromium Complexes—The First Direct Spectroscopic Observation of a Carbene Complex Intermediate

1997 ◽  
Vol 36 (24) ◽  
pp. 2828-2830 ◽  
Author(s):  
Jürgen Pfeiffer ◽  
Karl Heinz Dötz
Keyword(s):  
Spectroscopic Observation ◽  
Chromium Complexes ◽  
Enol Ethers ◽  
Carbene Complex

A Fischer-Type Ruthenium Carbene Complex as a Metathesis Catalyst for the Synthesis of Enol Ethers

2021 ◽  
Author(s):  
Xia-Lin Wang ◽  
Nicholas Yiching Chiang ◽  
Jian-Jhih Peng ◽  
Lei Yu ◽  
Li-Jun Xu ◽  
...  
Keyword(s):  
Enol Ethers ◽  
Carbene Complex ◽  
Metathesis Catalyst

On the Reactivity of mRNA Caps: C-H Oxidative Addition of 7-Methylguanosine to Pt(0)

2019 ◽  
Author(s):  
Maria Ines Leitao ◽  
Carmen Gonzalez ◽  
Zuzanna Filipiak ◽  
Ana Petronilho
Keyword(s):  
Oxidative Addition ◽  
Carbene Complex ◽  
Proton Loss

<p>7-methylguanosine, the so-called mRNA cap 0 bears a very labile C8-H bond, due to the formation of an ylide/N-heterocyclic carbene, upon proton loss. The reaction of 7-methylguanosine with Pt(PPh3)4, via C-H oxidative addition, yields a hydrido–PtII carbene complex and this reactivity can be extrapolated to 7,9-dimethylguanine. </p>

Pyrone-derived Marine Natural Products: A Review on Isolation, Bio-activities and Synthesis

2020 ◽  
Vol 24 (4) ◽  
pp. 354-401 ◽  
Author(s):  
Keisham S. Singh
Keyword(s):  
Natural Products ◽  
Marine Natural Products ◽  
Marine Fungi ◽  
Kojic Acid ◽  
Biological Activities ◽  
Biological Significance ◽  
Pyrone Ring ◽  
Enol Ethers ◽  
Bioactive Natural Products ◽  
Marine Metabolites

Marine natural products (MNPs) containing pyrone rings have been isolated from numerous marine organisms, and also produced by marine fungi and bacteria, particularly, actinomycetes. They constitute a versatile structure unit of bioactive natural products that exhibit various biological activities such as antibiotic, antifungal, cytotoxic, neurotoxic, phytotoxic and anti-tyrosinase. The two structure isomers of pyrone ring are &#947;- pyrone and &#945;-pyrone. In terms of chemical motif, &#947;-pyrone is the vinologous form of &#945;- pyrone which possesses a lactone ring. Actinomycete bacteria are responsible for the production of several &#945;-pyrone compounds such as elijopyrones A-D, salinipyrones and violapyrones etc. to name a few. A class of pyrone metabolites, polypropionates which have fascinating carbon skeleton, is primarily produced by marine molluscs. Interestingly, some of the pyrone polytketides which are found in cone snails are actually synthesized by actinomycete bacteria. Several pyrone derivatives have been obtained from marine fungi such as Aspergillums flavus, Altenaria sp., etc. The &#947;-pyrone derivative namely, kojic acid obtained from Aspergillus fungus has high commercial demand and finds various applications. Kojic acid and its derivative displayed inhibition of tyrosinase activity and, it is also extensively used as a ligand in coordination chemistry. Owing to their commercial and biological significance, the synthesis of pyrone containing compounds has been given attention over the past years. Few reviews on the total synthesis of pyrone containing natural products namely, polypropionate metabolites have been reported. However, these reviews skipped other marine pyrone metabolites and also omitted discussion on isolation and detailed biological activities. This review presents a brief account of the isolation of marine metabolites containing a pyrone ring and their reported bio-activities. Further, the review covers the synthesis of marine pyrone metabolites such as cyercene-A, placidenes, onchitriol-I, onchitriol-II, crispatene, photodeoxytrichidione, (-) membrenone-C, lihualide-B, macrocyclic enol ethers and auripyrones-A & B.

Addition of Allylsilanes and Silyl Enol Ethers to Small Oxygenated Rings: New Tools for Organic Synthesis

2014 ◽  
Vol 18 (5) ◽  
pp. 525-546 ◽  
Author(s):  
Carmen Hernandez-Cervantes ◽  
Miriam Alvarez-Corral ◽  
Manuel Munoz-Dorado ◽  
Ignacio Rodriguez-Garcia
Keyword(s):  
Organic Synthesis ◽  
Enol Ethers ◽  
Silyl Enol Ethers

α-Alkoxyalkyl Triphenylphosphonium Salts: Synthesis and Reactions

2019 ◽  
Vol 23 (16) ◽  
pp. 1738-1755
Author(s):  
Humaira Y. Gondal ◽  
Zain M. Cheema ◽  
Abdul R. Raza ◽  
Ahmed Abbaskhan ◽  
M. I. Chaudhary
Keyword(s):  
Carbonyl Compounds ◽  
Claisen Rearrangement ◽  
Alder Reaction ◽  
Coupling Reactions ◽  
Phosphonium Salts ◽  
Organic Transformations ◽  
Enol Ethers ◽  
Wide Range ◽  
Synthetic Methodologies ◽  
Alkoxy Groups

Following numerous applications of Wittig reaction now functionalized phosphonium salts are gaining attention due to their characteristic properties and diverse reactivity. This review is focused on &#945;-alkoxyalkyl triphenylphosphonium salts: an important class of functionalized phosphonium salts. Alkoxymethyltriphenylphosphonium salts are majorly employed in the carbon homologation of carbonyl compounds and preparation of enol ethers. Their methylene insertion strategy is extensively demonstrated in the total synthesis of a wide range of natural products and other important organic molecules. Similarly enol ethers prepared thereof are important precursors for different organic transformations like Diels-Alder reaction, Claisen rearrangement, Coupling reactions, Olefin metathesis and Nazarov cyclization. Reactivity of these &#945;-alkoxyalkylphosphonium salts have also been studied in the nucleophilic substitution reactions. A distinctive application of this class of phosphonium salts was recently reported in the phenylation of carbonyl compounds under very mild conditions. Synthesis of structurally diverse alkoxymethyltriphenylphosphonium salts with variation in alkoxy groups as well as counter anions are reported in literature. Here we present a detailed account of different synthetic methodologies for the preparation of this unique class of quaternary phosphonium salts and their applications in organic synthesis.

ChemInform Abstract: (2+2)CYCLOADDITIONS OF TETRACYANOETHYLENE TO ENOL ETHERS, STRUCTURE OF THE PRODUCT OF INTERCEPTION WITH ALCOHOL

1975 ◽  
Vol 6 (46) ◽  
pp. no-no
Author(s):  
ISABELLA KARLE ◽  
JUDITH FLIPPEN ◽  
ROLF HUISGEN ◽  
REINHARD SCHUG
Keyword(s):  
Enol Ethers
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