scholarly journals Ring Rearrangement Metathesis in 7-Oxabicyclo[2.2.1]heptene (7-Oxanorbornene) Derivatives. Some Applications in Natural Product Chemistry

2017 ◽  
Vol 12 (5) ◽  
pp. 1934578X1701200
Author(s):  
Silvia Roscales ◽  
Joaquín Plumet
Keyword(s):  
Diels Alder ◽  
Coupling Reactions ◽  
Alkyne Metathesis ◽  
Heck Reactions ◽  
One Pot ◽  
Cross Metathesis ◽  
Cross Coupling Reactions ◽  
Synthetic Procedure ◽  
Metathesis Reactions ◽  
Metal Catalyzed

Metathesis reactions is firmly established as a valuable synthetic tool in organic chemistry, clearly comparable with the venerable Diels-Alder and Wittig reactions and, more recently, with the metal-catalyzed cross-coupling reactions. Metathesis reactions can be considered as a fascinating synthetic methodology, allowing different variants regarding substrate (alkene and alkyne metathesis) and type of metathetical reactions. On the other hand, tandem metathesis reactions such Ring Rearrangement Metathesis (RRM) and the coupling of metathesis reaction with other reactions of alkenes such as Diels-Alder or Heck reactions, makes metathesis one of the most powerful and reliable synthetic procedure. In particular, Ring-Rearrangement Metathesis (RRM) refers to the combination of several metathesis transformations into a domino process such as ring-opening metathesis (ROM)/ring-closing metathesis (RCM) and ROM-cross metathesis (CM) in a one-pot operation. RRM delivers complex frameworks that are difficult to assemble by conventional methods constitutingan atom economic process. RRM is applicable to mono- and polycyclic systems of varying ring sizes such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, pyran systems, bicyclo[2.2.1]heptene derivatives, bicyclo[2.2.2]octene derivatives, bicyclo[3.2.1]octene derivatives and bicyclo[3.2.1]octene derivatives. In this review our attention has focused on the RRM reactions in 7-oxabicyclo[2.2.1]heptene derivatives and on their application in the synthesis of natural products or significant subunits of them.

Synthesis of Chlorinated Arenes and Hetarenes by One-Pot Cyclizations of 1,3-Bis-silyl Enol Ethers

Synlett ◽  
2019 ◽  
Vol 30 (06) ◽  
pp. 665-673 ◽  
Author(s):  
Peter Langer ◽  
Zahid Hassan
Keyword(s):  
Cost Effective ◽  
Coupling Reactions ◽  
One Pot ◽  
Enol Ethers ◽  
Silyl Enol Ethers ◽  
Cross Coupling Reactions ◽  
Silyl Enol Ether ◽  
Synthetic Routes ◽  
Metal Catalyzed ◽  
High Level

This account describes our recent findings and progress in synthesizing chlorinated arenes and hetarenes by one-pot cyclizations of 1,3-bis-silyl enol ether derivatives. These reactions allow for the preparation of highly functionalized products with a high level of regioselectivity. The synthetic routes are cost-effective avoiding additional functionalization steps. The products are difficult to be accessed by other methods. The chlorine atom is of relevance in medicinal and agriculture chemistry. In addition, it allows further functionalizations by transition-metal-catalyzed cross-coupling reactions.1 Introduction2 Cyclizations of 2-Chloro-1,3-bis(silyloxy)-1,3-butadienes2.1 3,5-Dihydroxychlorophthalates2.2 2,4-Dihydroxy-homochlorophthalates2.3 2-(Arylsulfonyl)chloropyridines2.4 1-Azaxanthones3 Cyclizations of 4-Chloro-1,3-bis(trimethylsilyloxy)-1,3-butadienes3.1 3-Chlorosalicylates3.2 Functionalized Chlorobiaryls3.3 3-Chloro-5-(2-chloroethyl)-salicylates3.4 2,4-Dihydroxychlorobenzophenones4 Cyclizations of 2-Chloro-3-(silyloxy)-2-en-1-ones4.1 Functionalized Chlorophenols4.2 Functionalized Chlorinated Biaryls and Chlorofluorenones4.3 Functionalized Chlorochromenones4.4 Functionalized 3-(Methylthio)chlorophenols4.5 Functionalized 3-Chloromethylphenols5 Conclusions6 List of Abbreviations

scholarly journals Non-Symmetrical Bis-Azine Biaryls from Chloroazines: A Strategy Using Phosphorus Ligand-Coupling

2019 ◽  
Author(s):  
Benjamin T. Boyle ◽  
Michael C. Hilton ◽  
Andrew McNally
Keyword(s):  
Cross Coupling ◽  
Coupling Reactions ◽  
One Pot ◽  
Cross Coupling Reactions ◽  
Alternative Approach ◽  
Metal Catalyzed ◽  
Traditional Approaches ◽  
Coupling Partner ◽  
Coupling Sequence

Distinct approaches to synthesize bis-azine biaryls are in demand as these compounds have multiple applications in the chemical sciences and are challenging targets for metal-catalyzed cross-coupling reactions. Most approaches focus on developing new reagents as the formal nucleophilic coupling partner that can function in metal-catalyzed processes. We present an alternative approach using pyridine and diazine phosphines as nucleophilic partners and chloroazines where the heterobiaryl bond is formed via a tandem S<sub><i>N</i></sub>Ar-phosphorus ligand-coupling sequence. The heteroaryl phosphines are prepared from chloroazines and are bench stable solids. Using this strategy, a range of bis-azine biaryls can be formed from abundant chloroazines that would be challenging using traditional approaches and a one-pot cross-electrophile coupling of two chloroazines is feasible.

scholarly journals Non-Symmetrical Bis-Azine Biaryls from Chloroazines: A Strategy Using Phosphorus Ligand-Coupling

2019 ◽  
Author(s):  
Benjamin T. Boyle ◽  
Michael C. Hilton ◽  
Andrew McNally
Keyword(s):  
Cross Coupling ◽  
Coupling Reactions ◽  
One Pot ◽  
Cross Coupling Reactions ◽  
Alternative Approach ◽  
Metal Catalyzed ◽  
Traditional Approaches ◽  
Coupling Partner ◽  
Coupling Sequence

Distinct approaches to synthesize bis-azine biaryls are in demand as these compounds have multiple applications in the chemical sciences and are challenging targets for metal-catalyzed cross-coupling reactions. Most approaches focus on developing new reagents as the formal nucleophilic coupling partner that can function in metal-catalyzed processes. We present an alternative approach using pyridine and diazine phosphines as nucleophilic partners and chloroazines where the heterobiaryl bond is formed via a tandem S<sub><i>N</i></sub>Ar-phosphorus ligand-coupling sequence. The heteroaryl phosphines are prepared from chloroazines and are bench stable solids. Using this strategy, a range of bis-azine biaryls can be formed from abundant chloroazines that would be challenging using traditional approaches and a one-pot cross-electrophile coupling of two chloroazines is feasible.

Optimized Synthesis of 7-Aza-Indazoles by Diels–Alder Cascade and Associated Process Safety

2020 ◽  
Author(s):  
Nicolas Brach ◽  
Vincent Le Fouler ◽  
Vincent Bizet ◽  
Marian Lanz ◽  
Pascale Hoehn ◽  
...  
Keyword(s):  
Cross Coupling ◽  
Diels Alder ◽  
Coupling Reactions ◽  
Process Safety ◽  
One Pot ◽  
Carbon And Nitrogen ◽  
Dsc Studies ◽  
Cross Coupling Reactions ◽  
Selection Of

Although pyrimidines are not among the most reac-tive partners in intramolecular inverse-electron de-mand [4πs+2πs] reactions with alkynes, they could be activated under mild and practical conditions, leading to fused nitrogen-containing heterocycles. We report an optimized synthesis of a 5-iodo-7-aza-indazole by a one-pot Diels–Alder cascade that starts from a pyrimidine substituted in the 2-position by an (alkynyl)hydrazone. The safety of the process was carefully studied by DSC studies. Eventually, a selection of cross-coupling reactions of 17 was studied and allowed the introduction of carbon- and nitrogen-based nucleophiles at the C5-position in good to excellent yields.

scholarly journals Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

2014 ◽  
Vol 10 ◽  
pp. 3031-3037 ◽  
Author(s):  
Kuppusamy Bharathimohan ◽  
Thanasekaran Ponpandian ◽  
A Jafar Ahamed ◽  
Nattamai Bhuvanesh
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
One Pot ◽  
Triazole Derivatives ◽  
One Pot Synthesis ◽  
Cross Coupling Reactions ◽  
Dehydrogenative Coupling ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

Herein, we describe a one-pot protocol for the synthesis of a novel series of polycyclic triazole derivatives. Transition metal-catalyzed decarboxylative CuAAC and dehydrogenative cross coupling reactions are combined in a single flask and achieved good yields of the respective triazoles (up to 97% yield). This methodology is more convenient to produce the complex polycyclic molecules in a simple way.

The Role of PEG on Pd- and Cu-Catalyzed Cross-Coupling Reactions

Synthesis ◽  
2017 ◽  
Vol 49 (11) ◽  
pp. 2337-2350 ◽  
Author(s):  
Marina Pires ◽  
Sara Purificação ◽  
A. Santos ◽  
M. Marques
Keyword(s):  
Phase Transfer ◽  
Cross Coupling ◽  
Polymer Support ◽  
Coupling Reactions ◽  
Heck Reactions ◽  
Cross Coupling Reactions ◽  
Direct Formation ◽  
Metal Catalyzed ◽  
Sonogashira Reactions

Carbon–carbon and carbon–heteroatom coupling reactions are among the most important transformations in organic synthesis as they enable complex structures to be formed from readily available compounds under different routes and conditions. Several metal-catalyzed cross-coupling reactions have been developed creating many efficient methods accessible for the direct formation of new bonds between differently hybridized carbon atoms.During the last decade, much effort has been devoted towards improvement of the sustainability of these reactions, such as catalyst recovery and atom efficiency. Polyethylene glycol (PEG) can be used as a medium, as solid-liquid phase transfer catalyst, or even as a polymer support. PEG has been investigated in a wide variety of cross-coupling reactions either as an alternative solvent to the common organic solvents or as a support for catalyst, substrate, and ligand. In this review we will summarize the different roles of PEG in palladium- and copper-catalyzed cross-coupling reactions, with the focus on Heck, Suzuki–Miyaura, Sonogashira, Buchwald–Hartwig, Stille, Fukuyama, and homocoupling reactions. We will highlight the role of PEG, the preparation of PEGylated catalysts and substrates, and the importance for the reaction outcome and applicability.1 Introduction2 PEG in Heck Reactions3 PEG in Homocoupling Reactions4 PEG in Suzuki–Miyaura Reactions5 PEG in Sonogashira Reactions6 PEG in Buchwald–Hartwig Reactions7 PEG in Stille Reactions8 PEG in Fukuyama Reactions9 PEG in Miscellaneous Cross-Coupling Routes10 Conclusions

Pd-Catalyzed Functionalization of Aryl Amines on a Soluble Polymer Support

Synlett ◽  
2020 ◽  
Vol 31 (20) ◽  
pp. 2027-2034
Author(s):  
M. Manuel B. Marques ◽  
A. Sofia Santos
Keyword(s):  
Polymer Support ◽  
Coupling Reactions ◽  
Proof Of Concept ◽  
Heck Reactions ◽  
Soluble Polymer ◽  
Cross Coupling Reactions ◽  
Aryl Amines ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Privileged Structures

AbstractHerein we report the use of a soluble polymer support PEG-2000 on Pd-catalyzed reactions to improve the functionalization of aromatic amines and the synthesis of N-heterocycles. Compatibility of metal-catalyzed reactions for assembling privileged structures such as functionalized anilines were studied. PEG-supported anilines were found to be suitable substrates for Pd-catalyzed N-arylation, Sonogashira and Heck reactions. PEGylated substrates were prepared in yields up to 94%. This work consists on a proof of concept on the use of PEGylated anilines on Pd-catalyzed cross-coupling reactions. Indole core was attained in 82% and 62% yields, via two different routes.

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