A simple strategy for the synthesis of optically pure trans-hydrindane systems

A new strategy for the synthesis of optically pure trans-hydrindane systems is reported from an easily available starting material.     

Synthesis of new difluoroalkyl propargylic ketones and their use for the preparation of fluorinated heterocycles

Synthetic methodology studies are reported towards the preparation of new propargylic ketones with CF₂R side chains. These molecules are used for the synthesis of various types of five- or six-membered heterocycles with difluoroalkyl side chains.     

A new synthon for the synthesis of aminoinositol derivatives

The regio- and stereoselective synthesis of a new synthon, trans-3,8-dioxatricyclo[3.2.1.0^2,4]octane-6,7-diamine, from 7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate is reported. Transformation of the acid functionalities to acyl azides followed by Curtius rearrangement gave the corresponding trans-diisocyanate, which was reacted with HCl to produce a trans-diamino compound that is a potentially important synthon for the versatile synthesis of aminocyclitols.     

An efficient total synthesis of 9-methoxycarbazole-3-carbaldehyde based on a novel methodology for the preparation of methoxyindoles

A direct synthesis of naturally occurring 9-methoxycarbazole-3-carbaldehyde 1, based on our methodology for the synthesis of 1-methoxyindoles, is reported. A novel benzannulation strategy was employed using ring closing metathesis as the key step in this total synthesis. The synthesis of the natural product 1 has been achieved in seven steps in 14% overall yield from commercial materials and in only four steps from a methoxyindole compound obtained using the new methodology.     

A facile construction of the tricyclic 5-7-6 scaffold of fungi-derived diterpenoids. The first total synthesis of (±)-heptemerone G and a new approach to Danishefsky’s intermediate for a guanacastepene A synthesis

The first total synthesis of (±)-heptemerone G, a diterpenoid metabolite of a submerged culture Coprinus heptemerus, and a new approach to an advanced intermediate for a synthesis of guanacastepene A are reported.     

A general and efficient method for the synthesis of benzo-(iso)quinoline derivatives

A new, short and efficient synthesis of substituted benzo-(iso)quinoline derivatives is reported. The methodology is based on a Suzuki or Negishi cross-coupling followed by a cyclization reaction induced by t-BuOK in DMF to form the central ring. This approach allowed the synthesis of all four benzo-(iso)quinoline isomers and the substitution of each ring of the benzo-(iso)quinoline core.     

Synthesis of the western half of breviones C, D, F and G

The enantioselective synthesis of the diterpenic moiety in the abeo-breviano skeleton is reported. The synthesis is carried out starting from 2-methyl-1,3-cyclohexanedione and EVK in eleven steps following a ring-expansion strategy once the tricyclic perhydrophenantrene skeleton has been obtained. A new Tiffeneau-Demjanov rearrangement under dark conditions is reported in which the insertion of the new methylene group is directed towards the most hindered side of the carbonyl group. This result is new and opposite to those reported in the literature under light (filtered or un-filtered wavelengths) conditions where insertion in the less hindered side is usually preferred.     

Microwave-assisted tandem reactions for the synthesis of 2-hydrazolyl-4-thiazolidinones

A tandem method for the synthesis of 2-hydrazolyl-4-thiazolidinones (5) from commercially available materials in a 3-component reaction has been developed. The reaction connects aldehydes, thiosemicarbazides, and maleic anhydride, effectively assisted by microwave irradiation. The synthesis of a new type of compound, 2-hydrazolyl-5,5-diphenyl-4-thiazolidinone (7), obtained by treatment of thiosemicarbazone with benzil in basic media is also reported. HOMO/LUMO energies, orbital coefficients, and charge distribution were used to explain the proposed reaction mechanism.     

Palladium‐Catalyzed Oxidative Carbonylation of N‐Allylamines for the Synthesis of β‐Lactams

β‐Lactam scaffolds are considered to be ideal building blocks for the synthesis of nitrogen‐containing compounds. A new palladium‐catalyzed oxidative carbonylation of N‐allylamines for the synthesis of α‐methylene‐β‐lactams is reported. DFT calculations suggest that the formation of β‐lactams via a four‐membered‐ring transition state is favorable.     

Synthesis and reaction of phthaloyl peroxide derivatives, potential organocatalysts for the stereospecific dihydroxylation of alkenes

To improve the synthesis and reactivity of phthaloyl peroxide derivatives a method has been developed using sodium percarbonate and phthaloyl chlorides. The reactions of the new phthaloyl peroxide derivatives with trans-stillbene as well as the improved reactivity of 3,4-dichlorophthaloyl peroxide with a variety of alkenes are reported.     

Electrochemical oxidaton of N,N-dialkyl-p-phenylenediamines in the presence of arylsulfinic acids. An efficient method for the synthesis of new sulfonamide derivatives

Electrochemical oxidation of N,N-dialkyl-p-phenylenediamines have been studied in the presence of arylsulfinic acids as nucleophiles in aqueous solutions. The results indicate that the electrochemically generated quinone-imines participate in Michael type addition reaction with arylsulfinic acids and via an EC mechanism convert to the corresponding new sulfonamide derivatives. In this work, an efficient and one-pot electrochemical method for the synthesis of new sulfonamide derivatives in aqueous solution is reported.     

Studies on the Synthesis of Trisaccharide Analogues of the Antibiotic Moenomycin A

A new approach for the synthesis of moenomycin trisaccharide analogues is reported in which three monosaccharide building blocks are used and allows the introduction of different substituents at the 6‐position of unit E (Scheme 2). Furthermore, a new procedure for the introduction and manipulation of unit F is described (Scheme 3).     

CoFe2O4@SiO2-PA-CC-guanidine nanoparticles: A novel,efficient, and recyclable catalyst for the synthesis of 3,5-disubstituted-2,6-dicyanoaniline derivatives

A new and efficient procedure for the synthesis of 3,5-disubstituted-2,6-dicyanoaniline derivatives by CoFe₂O₄@SiO₂-PA-CC-guanidine magnetic nanoparticles (MNPs) was reported. 3,5-Disubstituted-2,6-dicyanoaniline derivatives were synthesized from malononitrile, aldehydes, and β-nitrostyrene derivatives in good yields. MNPs used for the synthesis of aniline derivatives were easy to recover and reuse. The CoFe₂O₄@SiO₂-PA-CC-guanidine MNPs were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibration sample magnetometry techniques.     

An efficient one-pot reaction for the synthesis of pyrazolones bearing a phenothiazine unit

A simple one-pot approach for the synthesis of new pyrazolones containing a phenothiazine unit is reported. Compound 4b was evaluated for its antiproliferative activity on a NCI-60 cancer cell line panel and exhibited selective cytostatic activity toward CCRF-CEM, HL-60(TB), K-562, MOLT-4, and RPMI-8226 leukemia cell lines.     

Synthesis of JOSIPHOS-type ligands via a diastereoselective three-component reaction and their application in asymmetric rhodium-catalyzed hydroborations

The recently reported diastereoselective three-component reaction for the synthesis of chiral propargylamines was used for a new stereoselective synthesis of JOSIPHOS-type ligands 2a–d. The present synthesis gives the desired diphosphines in good yields without the need of resolution. Ligands 2a–d were applied to the rhodium-catalyzed hydroboration of styrene.     

Synthesis of prospective disaccharide ligands for Escherichia coli O157 verotoxin

The synthesis of new potential ligands for Escherichia coli 0157 verotoxin is reported, based on disaccharide fragments of the tetrasaccharide glycan portion of Gb₄ glycolipid. Intramolecular aglycone delivery was employed for the high-yielding and stereoselective production of the azidopropyl-tethered α-galactoside building block.     

Synthesis of 2,2-difluoro-3H-benzothiophen-3-ol via a difluorocarbene insertion reaction,investigating the scope for further derivatization

A simple, and efficient synthesis of 2,2-difluoro-3H-benzothiophen-3-ol using readily available sodium chlorodifluoroacetate (SCDA) is reported. We also explore new chemistry of these difluoro compounds. The salient feature of this approach includes operational simplicity and offers potential access to synthetically challenging building blocks for further elaboration. Functional group transformations of this new heterocycle are also presented.     

Studies with 1‐functionally substituted alkylbenzotriazoles: An efficient route for the synthesis of 1‐azolylbenzotriazoles,benzotriazolylazines and benzotriazolylazoloazines

A new approach to the synthesis of pyrazole, isoxazole, pyridine and pyrazolo[1,5‐α]pyrimidine deriva tives is reported. The structure of the newly synthesized compounds was elucidated by elemental analyses, ir and ¹H nmr spectra, and in some cases by ¹³C nmr investigation.     

Synthesis and Characterization of Hydrophilic Trityl Radical TFO for Biomedical and Biophysical Applications

Tetrathiatriarylmethyl (TAM, trityl) radicals have found wide applications as spin probes/labels for EPR spectroscopy and imaging, and as polarizing agents for dynamic nuclear polarization. The high hydrophilicity of TAM radicals is essential for their biomedical applications. However, the synthesis of hydrophilic TAM radicals (e.g., OX063) is extremely challenging and has only been reported in the patent literature, to date. Herein, an efficient synthesis of a highly water-soluble TAM radical bis(8-carboxyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d′]bis([1,3]dithiol-4-yl)-mono-(8-carboxyl-2,2,6,6-tetrakis(2-hydroxyethyl)benzo[1,2-d:4,5-d′]bis([1,3]dithiol-4-yl)methyl (TFO), which contains four additional hydroxylethyl groups, relative to the Finland trityl radical CT-03, is reported. Similar to OX063, TFO exhibits excellent properties, including high water solubility in phosphate buffer, low log P, low pK_a, long relaxation times, and negligible binding with bovine serum albumin. On the other hand, TFO has a sharper EPR line and higher O₂ sensitivity than those of OX063. Therefore, in combination with its facile synthesis, TFO should find wide applications in magnetic resonance related fields and this synthetic approach would shed new light on the synthesis of other hydrophilic TAM radicals.     

Stereoselective nitrenium ion cyclizations: asymmetric synthesis of the (+)-Kishi lactam and an intermediate for the preparation of fasicularin

The asymmetric synthesis of the (+)-Kishi lactam and an intermediate for the preparation of the marine natural product fasicularin is reported. The keystone of this divergent synthesis is the diastereoselective azaspirocyclization of an N-methoxy γ-arylbutanoamide, which is believed to proceed through the intermediacy of an N-acylnitrenium ion.