Synthesis Of Heterocyclic Rings Research Articles

Recent Progress in Palladium Catalysed Sustainable Synthesis of Heterocycles

Background: Palladium metal has been extensively used in the synthesis of organic molecules for the last few decades. Heterocyclic ring synthesis being a significant part of organic synthesis, transition metal catalysis, especially catalysis by palladium, has been actively employed in heterocyclic synthesis. However, since palladium is an expensive metal, there has always been an urge to reuse or recycle the palladium catalyst to make the process economically viable. Modern synthetic chemists are also in constant search for newer sustainable strategies for molecular synthesis, which will lead to eco-friendly synthetic protocols. Thus, in the last few years, palladium catalysed green synthesis of heterocycles has gained importance as these aim to make the synthetic organic chemical world slightly more sustainable. Methods: This review comprises palladium catalysed synthetic strategies that proceed in a sustainable fashion. A few protocols included here involve either organic solvent-free or greener solvents as reaction medium, which is one of the modes adopted towards sustainability. Other modes of sustainability included in this review are recyclability of the palladium catalyst, one pot tandem reaction strategy, use of air as oxidant, etc. All these modes aim at achieving one or the other green chemistry principles like reduction of waste and by-products, increasing atom economy, reduction of cost and use of safer solvents. Results: The review aims to reflect the scope of sustainability in palladium catalysed synthesis of heterocycles so that economically and environmentally viable synthetic methodologies may be selectively identified and applied in academia and industries. Conclusion: Keeping the principles of green chemistry in mind, in this review, we aim to compile the recent advancements in palladium catalysed sustainable synthesis of heterocycles in a single platter that may serve as a piece of reliable literature for further research in this area.

Metal and Non-Metal Catalysts in the Synthesis of Five-Membered S-Heterocycles.

A wide variety of biological activities are exhibited by N, O and S containing heterocycles and recently, many reports appeared for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal and non-metal catalyst has become a highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of S-heterocylces in the presence of metal and non-metal catalyst. The synthesis of five-membered S-heterocycles is described here. There is a need for the development of rapid, efficient and versatile strategy for the synthesis of heterocyclic rings. Metal, non-metal and organocatalysis involving methods have gained prominence because traditional conditions have disadvantages such as long reaction times, harsh conditions and limited substrate scope. The metal-, non-metal-, and organocatalyst assisted organic synthesis is a highly dynamic research field. For ßthe chemoselective and efficient synthesis of heterocyclic molecules, this protocol has emerged as a powerful route. Various methodologies in the past few years have been pointed out to pursue more sustainable, efficient and environmentally benign procedures and products. Among these processes, the development of new protocols (catalysis), which avoided the use of toxic reagents, are the focus of intense research.

Organic synthesis provides opportunities to transform drug discovery.

Despite decades of ground-breaking research in academia, organic synthesis is still a rate-limiting factor in drug-discovery projects. Here we present some current challenges in synthetic organic chemistry from the perspective of the pharmaceutical industry and highlight problematic steps that, if overcome, would find extensive application in the discovery of transformational medicines. Significant synthesis challenges arise from the fact that drug molecules typically contain amines and N-heterocycles, as well as unprotected polar groups. There is also a need for new reactions that enable non-traditional disconnections, more C-H bond activation and late-stage functionalization, as well as stereoselectively substituted aliphatic heterocyclic ring synthesis, C-X or C-C bond formation. We also emphasize that syntheses compatible with biomacromolecules will find increasing use, while new technologies such as machine-assisted approaches and artificial intelligence for synthesis planning have the potential to dramatically accelerate the drug-discovery process. We believe that increasing collaboration between academic and industrial chemists is crucial to address the challenges outlined here.

One-pot reaction for the synthesis of N-substituted 2-aminobenzoxazoles using triphenylbismuth dichloride as cyclodesulfurization reagent

The treatment of various 2-aminophenols with isothiocyanates afforded thioureas, which were reacted in situ with triphenylbismuth dichloride in the presence of triethylamine to give the expected N-substituted benzoxazol-2-amines in good to excellent yields. Triphenylbismuth dichloride promoted the successful cyclodesulfurization of thioureas with short reaction times under mild reaction conditions. This reaction is the first example of the synthesis of heterocyclic rings using a pentavalent organobismuth reagent.

Model studies for the synthesis of the antibiotic lactonamycin and the discovery of new reactions and mechanisms for the construction of substituted heterocycles

A new and highly efficient route for the construction of a model for the synthesis of lactonamycin 1 is reported. The chemistry has been utilised for the synthesis of heterocyclic rings, and new reactions for the synthesis of dienes and alkynes are reported.

Regiocontrolled Intramolecular Cyclizations of Carboxylic Acids to Carbon−Carbon Triple Bonds Promoted by Acid or Base Catalyst

We systematically investigated, for the first time, the relationship between regioselectivity and acid/base effects in the cyclization reactions between carboxylic acids and carbon-carbon triple bonds. We found novel acid- and base-promoted cyclizations to selectively give isocoumarin or pyran-2(2H)-one and phthalide or furan-2(5H)-one skeletons, respectively, and established a catalytic version of regioselective heterocyclic ring synthesis. Density functional theory calculations and application to a short route to thunberginol A were also described. [reaction: see text].

Hydroformylation of 1,4-diolefins in the presence of primary amines leading to heterocyclic compounds

The Rh(I)-catalysed hydroformylation of dienes in the presence of amines is applied to heterocyclic ring synthesis. Starting from 1,4-dienes pyrroles or eight-membered heterocycles are easily accessible. The selectivity of the reaction is controlled by the substitution pattern of the diolefin.

1,2-dithia-5-azacyclooctan-6-one and related compounds: Synthesis and conformation

The first synthesis of 1,2-dithia-5-azacyclooctan-6-one 11, the parent member of a heterocyclic ring synthesis is reported. Compound 11 was found by nOe experiments to exist in a conformation with a trans-amide bond. The substituted derivatives 12 and 13 were also prepared and compound 12 was found to possess a trans-amide bond whilst for compound 13 three conformations were identified with the major conformer possessing a cis-amide bond.

Vicarious Nucleophilic Substitution of Hydrogen in the Chemistry of Heterocyclic Compounds

Vicarious Nucleophilic Substitution of Hydrogen (VNS) is a valuable tool in the synthesis of heterocyclic compounds. Its application to the introduction of a variety of substituents to heteroarenes and to the synthesis of heterocyclic rings, such as indoles or quinolines, covering representative examples of reactions, is reviewed. 1. Introduction 2. General Description of the VNS Reaction 3. VNS of Hydrogen in Heteroarenes 3.1. VNS of Hydrogen in the Nitro Derivatives of Heteroarenes 3.2. VNS of Hydrogen in Heteroarenes that do not Contain Activating Substituents 4. Heterocyclic compounds as Nucleophilic Partners in VNS Reactions 5. Synthesis of Heterocyclic Rings via the VNS Reaction

ChemInform Abstract: Saturated Heterocyclic Ring Synthesis

ChemInformVolume 20, Issue 19 Reviews ChemInform Abstract: Saturated Heterocyclic Ring Synthesis K. COOPER, K. COOPER Pfizer, Cent. Res., Sandwich, Kent, UKSearch for more papers by this authorP. J. WHITTLE, P. J. WHITTLE Pfizer, Cent. Res., Sandwich, Kent, UKSearch for more papers by this author K. COOPER, K. COOPER Pfizer, Cent. Res., Sandwich, Kent, UKSearch for more papers by this authorP. J. WHITTLE, P. J. WHITTLE Pfizer, Cent. Res., Sandwich, Kent, UKSearch for more papers by this author First published: May 9, 1989 https://doi.org/10.1002/chin.198919340Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume20, Issue19May 9, 1989 RelatedInformation

ChemInform Abstract: Saturated Heterocyclic Ring Synthesis

ChemInformVolume 19, Issue 15 Reviews ChemInform Abstract: Saturated Heterocyclic Ring Synthesis K. COOPER, Pfizer Cent. Res., Sandwich/Kent, UKSearch for more papers by this authorP. J. WHITTLE, Pfizer Cent. Res., Sandwich/Kent, UKSearch for more papers by this author K. COOPER, Pfizer Cent. Res., Sandwich/Kent, UKSearch for more papers by this authorP. J. WHITTLE, Pfizer Cent. Res., Sandwich/Kent, UKSearch for more papers by this author First published: April 12, 1988 https://doi.org/10.1002/chin.198815393Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume19, Issue15April 12, 1988 RelatedInformation

ChemInform Abstract: Novel Reactions of Carbon Suboxide. Part 7. Synthesis of Heterocyclic Rings by Reaction with Bifunctional Aliphatic Compounds.

AbstractCyclization of the hydroxy oximes (I), (IV), and (VI) with carbon suboxide (II) gives the unsaturated lactones (III), (V), and (VII).

ChemInform Abstract: Saturated Heterocyclic Ring Synthesis

ChemInformVolume 18, Issue 25 Reviews ChemInform Abstract: Saturated Heterocyclic Ring Synthesis K. COOPER, K. COOPER Pfizer Cent. Res., Sandwich/Kent, UKSearch for more papers by this authorP. J. WHITTLE, P. J. WHITTLE Pfizer Cent. Res., Sandwich/Kent, UKSearch for more papers by this author K. COOPER, K. COOPER Pfizer Cent. Res., Sandwich/Kent, UKSearch for more papers by this authorP. J. WHITTLE, P. J. WHITTLE Pfizer Cent. Res., Sandwich/Kent, UKSearch for more papers by this author First published: June 23, 1987 https://doi.org/10.1002/chin.198725349Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume18, Issue25June 23, 1987 RelatedInformation

Novel Reactions of Carbon Suboxide. VII. Synthesis of Heterocyclic Rings by Reaction with Bifunctional Aliphatic Compounds

Reactions du sous-oxyde de carbone avec des oximes d'hydroxy-1 acetone ou hydroxy-4 butanones-2 ou avec l'ethylenediamine, l'ethanolamine ou des glycols: synthese de furannes, pyrannes, oxepinnes, diazepinnes-1,4, oxazepines-1,4 et dioxepannes-1,4

ChemInform Abstract: SATURATED HETEROCYCLIC RING SYNTHESIS

Chemischer InformationsdienstVolume 16, Issue 45 Reviews ChemInform Abstract: SATURATED HETEROCYCLIC RING SYNTHESIS R. C. BROWN, R. C. BROWNSearch for more papers by this author R. C. BROWN, R. C. BROWNSearch for more papers by this author First published: November 12, 1985 https://doi.org/10.1002/chin.198545341AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume16, Issue45November 12, 1985 RelatedInformation

ChemInform Abstract: Saturated Heterocyclic Ring Synthesis

Chemischer InformationsdienstVolume 15, Issue 13 Reviews ChemInform Abstract: Saturated Heterocyclic Ring Synthesis R. C. BROWN, R. C. BROWNSearch for more papers by this author R. C. BROWN, R. C. BROWNSearch for more papers by this author First published: March 27, 1984 https://doi.org/10.1002/chin.198413362Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume15, Issue13March 27, 1984 RelatedInformation

ChemInform Abstract: SATURATED HETEROCYCLIC RING SYNTHESIS

Chemischer InformationsdienstVolume 15, Issue 8 Reviews ChemInform Abstract: SATURATED HETEROCYCLIC RING SYNTHESIS R. C. BROWN, R. C. BROWNSearch for more papers by this author R. C. BROWN, R. C. BROWNSearch for more papers by this author First published: February 21, 1984 https://doi.org/10.1002/chin.198408331Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume15, Issue8February 21, 1984 RelatedInformation

ChemInform Abstract: Saturated Heterocyclic Ring Synthesis (201 Literaturangaben).

Chemischer InformationsdienstVolume 13, Issue 29 Reviews ChemInform Abstract: Saturated Heterocyclic Ring Synthesis (201 Literaturangaben). W. J. ROSS, W. J. ROSSSearch for more papers by this author W. J. ROSS, W. J. ROSSSearch for more papers by this author First published: July 20, 1982 https://doi.org/10.1002/chin.198229335AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume13, Issue29July 20, 1982 RelatedInformation

ChemInform Abstract: GENERAL AND SYNTHETIC METHODS. SATURATED HETEROCYCLIC RING SYNTHESIS

Chemischer InformationsdienstVolume 12, Issue 11 Reviews ChemInform Abstract: GENERAL AND SYNTHETIC METHODS. SATURATED HETEROCYCLIC RING SYNTHESIS W. J. ROSS, W. J. ROSSSearch for more papers by this author W. J. ROSS, W. J. ROSSSearch for more papers by this author First published: March 17, 1981 https://doi.org/10.1002/chin.198111377AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue11March 17, 1981 RelatedInformation

New trends in high polymer synthesis, and structural characteristics of the new materials

AbstractThe development of the polymer chemistry during the last decade is characterized by the existence of several new methods of polymerization, e. g. the isomerization polymerization of aliphatic hydrocarbons, the oxidative catalytic polymerization of aromatics, the photochemical polyaddition, the 1.3 and 1.4 dipolar polycycloadditions, the two step polycondensation processes. Some of these methods have already been applied on an industrial scale. Simultaneously new catalytic procedures were discovered, some of which permit stereoregular copolymerization, and very recently stereo‐elective polymerization. These different aspects will be considered successively.The isomerization polymerization in which the chain growth is characterized by alternate addition isomerization steps, is illustrated by several examples, and compared to the polymerizations with previous monomer isomerization, as in the case of β‐olefins.The stepwise oxidative coupling of different 2.6 disubstituted phenols, with oxygen in the presence of amine complexes of copper salts is considered from kinetic and structural point of view and compared with the oxidative FRIEDEL‐CRAFTS reaction on aromatic hydrocarbons.Two types of photochemical polyadditions are considered on the basis of the cyclomerization reaction, in which cyclobutane rings are formed by dimerization of olefins (in solution and in the solid state), and of the reductive dimerization, e. g. of bisarylketones into polypinacols.The use of 1.3 dipolar cycloaddition for the synthesis of heterocyclic rings containing polymers is illustrated and some properties of these polymers are described. Similarly the 1.4 DIELS‐ALDER cycloaddition is exemplified by the synthesis of polyphenylenes as described from biscyclopentadienones or (and) bis‐phenylenebispyrones and diethinylbenzene.Only short mention will be made on the synthesis of thermally stable polymers by polyheterocyclization, e. g. single strand benzoxazole‐ and benzthiazole‐imide copolymers and Kapton fibre, and double strand ladder polypyrrolone‐anthrachinone fibres. New catalytic procedures are finally briefly commented as far as they offer possibilities for the synthesis of new polymers and regular copolymers. Some properties of these new polymers are reported.