Metal and organo-complex promoted synthesis of fused five-membered O-heterocycles

Abstract

One of the highly emerging and an important aspect of organic chemistry is the metal and organo-complex promoted synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist due to their high cost, highly sophisticated instrumentation and problematic methods. For both stereoselective and regioselective synthesis of fused five-membered O-containing heterocycles, cyclic reactions that are metal and organo-complex promoted have been known to be very efficient. The present review article covers the different applications of metals and organo-complexes in the formation of fused five-membered oxygen containing fused heterocycles. The fascinating research that has been done in this area is enclosed in this review.     

Microwave-Assisted Synthesis: Fused Five-Membered N-Heterocycles

The development of new strategies for the synthesis of small-sized heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in nitrogen-containing fused five-membered heterocyclic compounds synthesis is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of fused N-heterocycles.     

Role of Microwaves in the Synthesis of Fused Five-Membered Heterocycles with Three N-Heteroatoms

The development of new strategies for the synthesis of small-sized heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in three nitrogen atoms containing fused five-membered heterocyclic compounds synthesis is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of N,N,N-heterocycles. The literature data are summarized based on the type of cycles.     

A general and efficient palladium-catalyzed intramolecular cyclization reaction of beta-brominated porphyrins

A general and efficient synthesis of fused five-membered porphyrins from the readily available beta-brominated porphyrins via palladium-catalyzed intramolecular cyclization has been developed, which can be applied for various metal complexes of beta-brominated porphyrins or free base ones and generally results in good yields of the fused five-membered porphyrins.     

Microwave-Assisted Synthesis of Five-Membered O-Heterocycles

The development of new strategies for synthesis of five-membered O-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in oxygen-containing five-membered heterocyclic compound synthesis is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of five-membered O-heterocycles.     

Microwave-Assisted Synthesis of Five-Membered O,N-Heterocycles

The development of new strategies for the synthesis of five-membered O,N-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in oxygen- and nitrogen-containing five-membered heterocyclic compounds synthesis is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of five-membered O,N-heterocycles.     

Microwave-Assisted Synthesis of Five-Membered O,N,N-Heterocycles

The development of new strategies for synthesis of five-membered O,N,N-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in oxygen and two nitrogen atoms containing five-membered heterocyclic compounds synthesis is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of five-membered O,N,N-heterocycles.     

Unusual light-driven amplification through unexpected regioselective photogeneration of five-membered azaheterocyclic AIEgen

Developing versatile synthetic methodologies with merits of simplicity, efficiency, and environment friendliness for five-membered heterocycles is of incredible importance to pharmaceutical and material science, as well as a huge challenge to synthetic chemistry. Herein, an unexpected regioselective photoreaction to construct a fused five-membered azaheterocycle with an aggregation-induced emission (AIE) characteristic is developed under mild conditions. The formation of the five-membered ring is both thermodynamically and kinetically favored, as justified by theoretical calculation and experimental evidence. Markedly, a light-driven amplification strategy is proposed and applied in selective mitochondria-targeted cancer cell recognition and fluorescent photopattern fabrication with improved resolution. The work not only delivers the first report on efficiently generating a fused five-membered azaheterocyclic AIE luminogen under mild conditions via photoreaction, but also offers deep insight into the essence of the photosynthesis of fused five-membered azaheterocyclic compounds.

A multifunctional, AIE-based, fused five-membered azaheterocycle is photogenerated with light-driven amplification to combat the photobleaching issue and fabricate display materials.     

Environmentally Benign Synthesis of Five-Membered 1,3-N,N-Heterocycles by Microwave Irradiation

The development of new strategies for the synthesis of small-sized heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in the synthesis of five-membered heterocyclic compounds containing two nitrogen atoms is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of five-membered 1,3-N,N-heterocycles.     

Insight into Microwave-Assisted Synthesis of Benzo Derivatives of Five-Membered N,N-Heterocycles

The development of new strategies for the synthesis of small-sized heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in nitrogen-containing benzo derivatives of five-membered heterocyclic compounds synthesis is presented here, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of benzo derivatives of five-membered N,N-heterocycles.     

Recent Impact of Microwave-Assisted Synthesis on Benzo Derivatives of Five-Membered N-Heterocycles

The development of new strategies for the synthesis of small-sized heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in nitrogen-containing benzo derivatives of five-membered heterocyclic compounds synthesis is presented here, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of benzo derivatives of five-membered N-heterocycles.     

SYNTHESIS OF SOME NEW 1,2,4-TRIAZOLO[3,4-b]-THIADIAZOLE DERIVATIVES AS POSSIBLE ANTICANCER AGENTS

3-Substituted-4-amino-5-mercapto-1,2,4-triazoles are versatile synthons for constructing various biologically active heterocycles. Their cyclization with carboxylic acids gives fused five-membered derivatives, whereas with α-bromoketones gives a six-membered heterocycle. In this article we report the synthesis of a series of 1,2,4-triazolo[3,4-b]thiadiazoles 5 starting from 4-amino-3-substituted-5-mercapto-1,2,4-triazoles 3 and fluorobenzoic acids 4 using phosphorous oxychloride as cyclizing agent. Fourteen of the newly synthesized compounds were screened for anticancer properties. Four among them showed in vitro anticancer activity.     

Silver-Catalyzed and Silver-Promoted Reactions of Isocyanides

In recent years, the silver-catalyzed and silver-promoted isocyanide reactions have attracted much attention, due to its efficiency in the formation of diverse new bonds and good reaction selectivity. A series of highly useful linear or cyclic compounds have been constructed. In this review, the recent progress in this field is described in the sequence of synthesis of five-membered heterocyclic compounds, synthesis of six-membered heterocyclic compounds, synthesis of fused cyclic compounds as well as synthesis of linear nitrogen-containing compounds.     

Approaches to the Synthesis of Gibberellic Acid. Construction of the B,C and D Ring System

One of the most challenging aspects of the synthesis of gibberellic acid² and structurally related compounds such as steviol³ is the construction of the bicyclo[3.2.1]octane system with the unusual features of an exocyclic methylene group adjacent to a bridgehead tertiary hydroxyl group. In gibberellic acid this structural feature comprises the C, D ring system, which is fused to the five-membered B ring.     

肼类衍生物在五元唑类杂环合成中的应用进展

简要概述了肼类衍生物的结构及反应活性,总结了近十年来肼类衍生物分别在合成五元唑类杂环如吡唑、噻唑、1,3,4-噁二唑、1,3,4-噻二唑以及三唑类化合物,及其相关的稠杂环如吡唑并某环、s-三唑[3,4-b][1,3,4]-噻二唑、s-三唑[3,4-b][1,3,4]-噻二嗪,以及含有1,2,4-三唑的稠杂环化合物等合成中的应用进展.     

Advances in Microwave-Assisted Synthesis for Five-Membered N-Heterocycle Synthesis

The development of new strategies for the synthesis of small-sized heterocycles hasremained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in the synthesis of nitrogen-containing five-membered heterocyclic compounds is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of N-heterocycles.     

Microwave-assisted synthesis of five-membered S-heterocycles

The development of new strategies for synthesis of five-membered S-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in sulfur-containing five-membered heterocyclic compounds synthesis is presented, focusing on the developments in the last 5–10 years. This contribution covers the literature concerning the total synthesis of five-membered S-heterocycles under microwave and combined effect of microwave and solid-phase.     

A new synthetic approach towards isoquinobenzazepinone and isoindolinobenzazepinone using acid-mediated cyclisation and Heck reaction

Six-membered ring cyclisation of N-ethylbenzazepinone, prepared from the condensation of benzazepinone with phenethyl iodide under basic conditions, smoothly provided the corresponding product, isoquino[1,2-b][3]benzazepinone, under acid-mediated conditions. On the other hand, the attempted direct five-membered ring cyclisation using the acid-mediated conditions failed to give the 7,5 fused ring isoindolinobenzazepinone from N-benzylbenzazepinone, but the 7,6 fused ring product was instead obtained. However, five-membered ring cyclisation of N-benzylbenzazepinone could be effected efficiently by employing the Heck reaction followed by catalytic hydrogenation to furnish the desired isoindolinobenzazepinone.     

Cycloisomerization of 1,6-enynes using acetate as a nucleophile under palladium(II) catalysis

[reaction: see text] An efficient method for the synthesis of five-membered carbo- and heterocyclic compounds, including fused rings, was reported using acetate as a nucleophile in the cyclization of 1,6-enynes under palladium(II) catalysis. The reaction is initiated by trans-acetoxypalladation of the alkynes and quenched by either trans- or cis-deacetoxypalladation in the presence of 2,2'-bipyridine as the ligand. An example of the catalytic asymmetric cyclization is presented with moderate enantioselectivity using chiral bisoxazoline ligand.     

Unexpected four- and eight-membered organo P-Se heterocycles

Reaction of [PhP(Se)(micro-Se)](2) (Woollins' reagent, WR) with symmetrically disubstituted diynes: five-membered P(Se)Se(2)C(2) heterocycles and bis-heterocycles with two five-membered P(Se)Se(2)C(2) rings connected through a C-C single bond; (t)Bu-C[triple bond, length as m-dash]C-C[triple bond, length as m-dash]C-(t)Bu reacts differently to afford an unprecedented four-membered P(Se)SeC(2) heterocycle with one unreacted triple bond and a fused bis-heterocycle containing two five-membered P(Se)SeC(3) rings fused at the middle two carbons of the diyne to give a heterocyclic analogue of pentalene, [3.3.0]octa-1-6-diene.