Microwave-Assisted Synthesis of Six-Membered S-Heterocycles

The development of new strategies for synthesis of six-membered S-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in sulfur-containing six-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 six-membered S-heterocycles.     

Microwave-Assisted Synthesis of Six-Membered O,O-Heterocycles

The development of new strategies for synthesis of six-membered O,O-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in two oxygen atoms containing six-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 six-membered O,O-heterocycles.     

Microwave-Assisted Synthesis of Six-Membered O-Heterocycles

The development of new strategies for synthesis of six-membered O-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in oxygen-containing six-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 six membered O-heterocycles.     

Applications of Microwaves in the Synthesis of Polycyclic Six-Membered N,N-Heterocycles

The development of new strategies for the synthesis of polycyclic heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in the synthesis of six-membered polycyclic 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 six-membered polycyclic N,N-heterocycles.     

Synthesis and study of a heterocyclic receptor designed for carboxylic acids

The synthesis of a tricyclic receptor having a bowl shape and three binding points for carboxylic acids has been achieved starting from readily available 1-tetralone derivatives according to two different methods. This host possesses a six-membered lactam moiety and a carboxamide at the end of a flexible arm. Association constant with benzoic acid and stoichiometry of the complex have been determined using ¹H NMR dilution experiments.     

Synthesis of 1-aryl- benzocycloalkane derivatives via one-pot two-step reaction of benzocyclonone,tosylhydrazide, and arylboronic acid

A metal-free one-pot two-step reductive coupling reaction of benzocyclonone, tosylhydrazide, and arylboronic acid was developed for the formation of a C(sp³)–C(sp²) bond, which enabled the efficient synthesis of 1-aryl-benzocycloalkane compounds in moderate to good yields on a multi-gram scale. Moreover, five- and six-membered benzocyclic ketones are also suitable substrates for this reaction. Notably, this protocol was also found to be suitable for synthesizing 3-(3,4-dichlorophenyl)-2,3-dihydro-1H-inden-1-one, an important intermediate in the synthesis of indatraline.     

Review on the Synthesis of Six-MemberedN,N-Heterocycles by Microwave Irradiation

Abstract

The development of new strategies for 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 six-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 N,N-heterocycles.     

Cu-assisted C–N bond formations in six-membered N-heterocycle synthesis

Abstract

One of the highly emerging and important aspect of organic chemistry is the metal-catalyzed synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist because of their high cost, highly specified instrumentation and inconvenient methods. For both the stereoselective and regioselective synthesis of six-membered nitrogen-containing heterocycles, cyclic reactions that are Cu-catalyzed have known to be very efficient. The presented review covers the varied applications of Cu as a catalyst and its importance in the formation of six-membered nitrogen-containing heterocycles. The fascinating research that has been done in this area is also enclosed in this review.     

Polycyclic Six-Membered N-Heterocycles: Microwave-Assisted Synthesis

The development of new strategies for synthesis of polycyclic heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in nitrogen-containing six-membered polycyclic 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-heterocycles.     

Microwave-Assisted Synthesis of Fused Polycyclic Six-Membered N-Heterocycles

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

A propanediamine-bridged dinuclear iron(III) complex: Synthesis,X-ray analyses,spectral studies,and magnetic properties

A new propylenediamine-bridged diunclear complex formulated as [Fe₂(Salpn)₃] (I) (pn = 1,2-propylenediamine, H₂Salpn = N,N′-bis(salicylaldehyde)propylenediamine Schiff base) has been prepared from the template synthesis by the reaction of 1,2-propylenediamine with salicylaldehyde in the presence of the iron(III) salt. The metal centers adopt a slightly distorted octahedral geometry, and the Salpn ligands act in both bridging and chelating modes to form a dinuclear complex with the six-membered chelate rings. The magnetic susceptibility investigation for I indicates the presence of very weak antiferromagnetic coupling between the Fe³⁺ cations through the propylenediamine bridge.     

Greener and Expeditious Synthesis of Fused Six-Membered N,N-Heterocycles Using Microwave Irradiation

The development of new strategies for the synthesis of fused heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in the synthesis of fused six-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 fused N,N-heterocycles.     

Review of Microwave-Assisted Synthesis of Benzo-Fused Six-Membered N,N-Heterocycles

The development of new strategies for synthesis of fused heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in nitrogen-containing benzo-fused six-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 benzo-fused N,N-heterocycles.     

Ag-mediated synthesis of six-membered N-heterocycles

Abstract

One of the highly emerging and an important aspect of organic chemistry is the metal catalyzed synthesis of heterocycles. The methods used earlier for the synthesis of heterocycles were significant in the organic synthesis and developing cost-effective, improved and facial methods were beneficial to construct the complex architectures. For the both stereoselective and regioselective synthesis of six-membered nitrogen containing heterocycles, cyclic reactions that are Ag-mediated have known to be very efficient. The present review covers the applications of Ag in the formation of six-membered nitrogen containing heterocycles.     

Preparation,Reactions, and Stereochemistry of 4-Tert-Butyl-1-Chlorophosphorinane 1-Sulfide and Derivatives

Abstract

Nucleophilic substitution at tetracoordinated phosphorus centers has been extensively investigated.¹ Transesterification of acyclic phosphinates proceeds with inversion of configuration,² whereas four-membered phosphinates react with retention.³ In previous work⁴ we suggested that transesterification in six-membered phosphinates occurs via an S_N2 mechanism. The title compound was synthesized as a model structure to study the stereochemical and mechanistic aspects of nucleophlic substitution at phosphorus in a six-membered ring. A mixture of diastereomers was produced and separated by column chromatography. Both the mixture and separate isomers were used for an investigation of substitution with methanol, methoxide ions, and phenoxide ions; the reactions proceeded with inversion. Transesterification reactions of the resulting thiophosphinates were studied and found to proceed with inversion. Reactions of these with phenyllithium, benzyllithium, lithium phenylacetylide, and the corresponding organomagnesium halides were also carried out. The stereochemical assignments for the title compound (cis and trans) and two derivatives have been firmly anchored by X-ray studies;⁵ assignments for others are tentative and based on spectroscopic measurements, including ¹H, ¹³C, and ³¹P NMR data.     

One-pot synthesis of conformationally restricted spirooxindoles

Diastereomeric three-, five- and six-membered spirocycloalkyloxindoles were successfully synthesized in a rapid and convenient manner from readily accessible starting materials in moderate to high yields using 1-methyl-3-acetonitriloxindole after a one-pot base-mediated double-alkylation strategy. It was found that the diastereoselection is dependent on the reaction conditions and the spirocycloalkyl ring size, with the 3R^∗,8R^∗ diastereomers being thermodynamically favored under the basic reaction conditions for three- and five-membered rings, and the 3R^∗,8S^∗ diastereomer in the case of six-membered rings, as predicted by DFT calculations. The relative stereochemistry was supported by 2D NMR spectra and X-ray crystal structural analysis. The conformational rigidity of the spirocycloalkyloxindoles in solution was established based on NMR experimental and theoretical DFT approaches.     

Square planar 1:1 halide complexes of nickel(II), copper(II), palladium(II) and gold(III) with deprotonated N,N,Z-tridentate hydrazones (Z = S or O) derived from 6-amino-5-formyl-1,3-dimethyluracil

The synthesis and spectroscopic characterization of Ni^II, Cu^II, Pd^II and Au^III complexes containing hydrazones derived from 6-amino-5-formyl-1,3-dimethyluracil and thiosemicarbazide, acetylhydrazine and nicotinic acid is reported. In all cases, the complexes appear to be monomeric and square planar, with three positions occupied by the N,N,Z-tridentate (Z = S or O) ligand, making two five- and six-membered chelate rings and the fourth position occupied by halide.     

Hybrid density functional theory investigation of a series of alloxan-based thiosemicarbazones and semicarbazones

Recently, the synthesis and the NMR characterization of a series of eight alloxan-based thiosemicarbazones and semicarbazones were reported. These compounds exhibit a strongly hydrogenbonded hydrazinic proton that is a part of a characteristic six-membered ring. This proton is highly deshielded and resonates far downfield in the proton NMR spectra. In this report, mPW1PW91/6-31+G(d,p) calculations have been used to investigate the structure and other molecular properties of this series of eight compounds. The relationship between the ¹H and ¹³C NMR chemical shifts and various geometric parameters was investigated, and linear relationships for proton peaks that are involved in hydrogen-bond interactions were found.     

Diastereoselective synthesis of a novel lactam peptidomimetic exploiting vinylogous Mannich addition of 2-silyloxyfuran reagents

The total synthesis of a potential inhibitor of HIV-protease—the chiral nonracemic six-membered hydroxy lactam 6—has been accomplished, that involves, as key reaction, the highly diastereoselective vinylogous Mannich addition of furan-based silyloxy diene 7 to glyceraldeyde imine 8.     

Square planar complexes of nickel(II), palladium(II) and platinum(II) with 1-(2-hydroxyphenyl)-3,5-diphenylformazan

Summary A novel series of formazan complexes of general formula FoML [H₂Fo = 1-(2-hydroxyphenyl)-3,5-diphenylformazan; M = Ni^II, Pd^II or Pt^II; L = NH₃, py and Ph₃P] are described. The formazan nickel(II) system shows linkage isomerism; one isomer, A, contains an unusual five-membered formazan chelate ring, whereas the other, isomer B, has the usual six-membered ring.¹³C n.m.r., u.v. and i.r. spectra are presented and interpreted. From these the palladium and platinum complexes appear to contain the six-membered ring of the B type isomer.