Synthesis and functionalization of N-sulfinyl imines: Sonogashira reaction and copper-catalyzed azide-alkyne cycloaddition

A small library of novel molecules was generated using a rapid and efficient methodology for the synthesis of N-sulfinyl imine triazole compounds. The process involves a coupling step from the Sonogashira cross-coupling reaction and then, in a one-step reaction, deprotection of the trimethylsilyl group and triazole heterocyclic ring formation using a microwave reactor.     

Chloramine-T (N-chloro-p-toluenesulfonamide sodium salt), a versatile reagent in organic synthesis and analytical chemistry: An up to date review

Chloramine-T (CAT), the sodium salt of N-chloro-p-toluenesulfonamide, is a low-cost mild oxidizing agent with a wide range of uses. Most importantly, it can be used in acidic, neutral, and basic conditions. As a result, it’s been widely used in chemistry, particularly in organic synthesis and analytical chemistry. Chloramine-T acts as a source of halonium cation and nitrogen anion and thus acts as base and nucleophile. It reacts with a wide range of functional groups and carries different molecular transformations. This paper thoroughly summarises and highlights the synthetic and analytical effectiveness of CAT. This study focuses on current developments as well as some older techniques in which CAT has been employed as an oxidizing agent. This review article stretches a comprehensive profile of the CAT reagent in organic synthesis and analytical chemistry, which will be very useful for further research exploration in this field.     

Three-component synthesis and antibacterial evaluation of some novel 1,2-dihydroisoquinoline derivatives

Isoquinoline reacts with dialkyl acetylenedicarboxylates in the presence of kojic acid or8-hydroxyquinoline to generate 1,2-dihydroisoquinoline derivatives. The simplicity, mild reaction conditions and high yields of products make it an interesting process compared to other approaches. The compounds have been analyzed for antibacterial activity against Gram negative and Gram positive bacteria. The results indicated that 1,2-dihydroisoquinolines derived from kojic acid are effective against all of the studied bacteria especially against Bacillus subtilis, while the products obtained from8-hydroxyquinoline are active only against Gram positive bacteria.     

One-pot synthesis of new iso-DPP derivatives from terminal alkynes and isocyanates

The reaction of phenyl acetylide anion with aryl isocyanates followed by quenching with water is shown to produce pyrrolopyrrole (iso-DPP) derivatives in addition to the isomeric cyclopentadienone imines previously reported. If the reaction is quenched with dilute HCl, 5-ylidenepyrrol-2(5H)-ones, formed by a Meyer-Schuster rearrangement, can be isolated instead. A possible mechanism for this reaction is suggested.     

An efficient synthesis of ferrocenyl substituted 3-cyanopyridine derivatives under ultrasound irradiation

An efficient synthesis of 2-alkoxy-4-aryl-6-ferrocenyl-3-cyanopyridines via the condensation of ferrocenyl substituted chalcones with malononitrile in a freshly prepared sodium alkoxide solution under ultrasound irradiation was investigated. Especially noteworthy, the reaction of 1-ferrocenyl-3-(pyridin-2-yl)prop-2-ene-1-one with malononitrile afforded 2-alkoxy-4-pyridyl-6-ferrocenylpyridine, with the loss of CN group on the 3-position of pyridine ring was first observed.     

Montmorillonite K10-catalyzed synthesis of N-fused imino-1,2,4-thiadiazolo isoquinoline derivatives

A novel synthesis of N-fused imino-1,2,4-thiadiazolo derivatives is described. This approach involves the inexpensive, nontoxic, recoverable, and easy to handle montmorillonite K10 that catalyzes the coupling of 3-aminoisoquinolines and phenylisothiocyanates to afford the N-fused imino-1,2,4-thiadiazolo isoquinoline motifs in exemplary yields. The main attractions of this synthetic strategy were simple procedure and excellent yields.     

Iodine-mediated electrophilic tandem cyclization of 2-alkynylbenzaldehydes with anthranilic acid leading to 1,2-dihydroisoquinoline-fused benzoxazinones

An efficient iodine-mediated electrophilic tandem cyclization of substituted 2-alkynylbenzaldehydes with anthranilic acids under basic medium leading to iodo-1,2-dihydroisoquinoline-fused benzoxazinones is presented. Success of the protocol for the reaction of substituted 2-alkynylbenzaldehydes with 2-aminobenzamides to furnish isoquinoline-fused quinazolinones is also described.     

Solid-phase synthesis of 2,3,4,5-tetrahydro-1H-benzo[e][1,4]diazepine derivatives

We have developed an efficient solid-phase synthetic approach for the synthesis of 2,3,4,5-tetrahydro-1H-benzo[e][1,4]diazepine derivatives. The methodology is of value for high throughput synthesis of these potentially bioactive molecules.     

Conversion of norbornene derivatives into vicinal-dithioethers via S8 activation

Norbornene reacts with elemental sulfur to give a mixture of trithiolane and pentathiepane. Sulfuration of norbornene derivatives was achieved with elemental sulfur, by using a catalytic amount of a nickel complex, to afford selectively the corresponding trithiolanes. The most effective catalytic system was Ni(NH₃)₆Cl₂ in dimethylformamide. The trithiolanes were reduced with super-hydride into 1,2-dithiolate salts, and quenched in situ to form vicinal-dithioethers.     

A novel and facile stereocontrolled synthetic method for polyhydro-quinolines and pyridopyridazines via a diene-transmissive Diels-Alder reaction involving inverse electron-demand hetero Diels-Alder cycloaddition of cross-conjugated azatrienes

Cross-conjugated azatrienes bearing an electron-withdrawing sulfonyl or benzoyl group on the nitrogen atom underwent, on heating or in the presence of a Lewis acid (TMSOTf), an initial inverse electron-demand hetero Diels-Alder reaction with electron-rich dienophiles (vinyl ether, vinyl thioether, and allenyl ether) to produce 1:1 cycloadducts with high endo selectivity. The initial cycloadducts thus obtained underwent a second Diels-Alder reaction stereoselectively on the newly formed diene unit with electron-deficient dienophiles to give the crossed bis-cycloadducts, octahydroquinolines, with high diastereo-π-facial selectivity. The N-sulfonylazatrienes tethering an ortho-cinnamyloxyphenyl dienophile at the triene terminal underwent an initial intramolecular hetero Diels-Alder reaction of the inverse electron-demand type. The subsequent second Diels-Alder reaction of the formed mono-cycloadducts completed the diene-transmissive hetero Diels-Alder protocol to give benzopyrano[3,4-c]quinolines in a highly stereoselective manner.     

The potential energy surface of the triazadiphosphole formation

The formal GaCl₃-assisted [3+2] cycloaddition of two (Me₃Si)₂N–N(SiMe₃)–PCl₂ molecules resulting in the formation of a triazadiphosphole has been studied by means of B3LYP/6-31G(d,p) computations. These calculations revealed a stepwise reaction mechanism starting from the disguised 1,3-dipole and dipolarophile (Me₃Si)₂N–N(SiMe₃)–PCl₂. Comparison of the potential energy surface for the formation of a triazadiphosphole in the presence and without a Lewis acid indicate, that addition of a Lewis acid such as GaCl₃ decreases the activation barriers to Me₃Si–Cl elimination, in accord with experiment. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Cyclopentadienylaluminum thiolates - synthesis and structure

The dicyclopentadienylaluminum thiolates [Cp₂Al(μ-SR)]₂, where R = Et (1), ⁱPr (2), were obtained by reacting Cl₂AlSR with CpNa at the molar ratio 1:2, respectively. Use of CpLi instead of CpNa at the same molar ratio of reagents leads to the formation of cyclopentadienyl(chloro)aluminum thiolates [Cp(Cl)Al(μ-SR)]₂, exclusively, where R = Et (3), ⁱPr (4), ⁱBu (5), and ⁿBu (6). The compounds were characterized by ¹H, ¹³C, and ²⁷Al NMR spectroscopy. The structures of the compounds 1 and 4 were determined by X-ray crystallography.     

Click chemistry inspired synthesis of ferrocene amino acids and other derivatives

This work reports the synthesis of a wide range of ferrocenyl-amino acids and other derivatives in excellent yield. Diverse amino acid containing azides were synthesized and ligated to ferrocene employing click reaction to access ferrocenyl amino acids. Chiral alcohols, esters, diols, amines containing azido group were tagged to ferrocene via click reaction to generate ferrocene derived chiral derivatives. A novel strategy for direct incorporation of ferrocene into a peptide and a new route to 1, 1′disubstituted ferrocene amino acid derivative are reported.     

An alternatively metal-free synthesis of 1,3,5-triazines or 1,2,4-thiadiazoles from benzyl chlorides and benzylamines mediated by elemental sulfur

An elemental sulfur mediated reaction of benzyl chlorides with benzylamines is developed, which allows the practical synthesis of valuable 1,3,5-triazines. This protocol that is metal free, ligand free, and uses inexpensive elemental sulfur as oxidant or raw material displays mild reaction conditions, a broad substrate scope and moderate to good yields. Moreover, the modified sulfur-mediated reaction system can also be used to synthesize 1,2,4-thiadiazoles, by simply switching the stoichiometry of sulfur powder from 0.75 equivalents to 5 equivalents.     

A practical system to synthesize the multiple-substituted 2,5-dihydrofuran by the intermolecular dipolar cycloaddition reactions involving acceptor/acceptor-substituted diazo reagents

A practical system for synthesizing the multiple-substituted 2,5-dihydrofuran through intermolecular dipolar cycloaddition reactions of acceptor/acceptor diazo reagents, aldehydes, and acetylenedicarboxylate was developed. The reactions proceeded effectively under ambient temperature with low reactant ratios. The control reactions revealed that there are two competitive paths: one forms 1,3-dioxolane and the other forms 2,5-dihydrofuran. These two paths could be controlled by modifying the steric hindrance of the diazo reagents.     

新型二茂稀土烃硫基配合物的合成与表征

本文用三茂基稀土[(C~5H~5)~3Ln(Ln=Ho(1)，Yb(2)，La(3)，Y(4)]与等摩尔的2-巯基嘧啶(HSC:NCH:CHCH:N·)在四氢呋喃溶剂中于室温下反应，合成了四个对空气敏感的二茂稀土嘧啶巯基配合物。产物经元素分析、红外光谱及质谱鉴定确定其组成为：(C~5H~5)~2LnSC:NCH:CHCH:N·THF[Ln=Ho(1)，Yb(2)，La(3)，Y(4)]。     

Solvothermal synthesis of silver nanoparticles from thiolates

A new solvothermal method for the synthesis of thiol-protected silver nanoparticles starting from silver thiolates is reported. The method has been tried with thiols of different chain length, such as octane and octadecane thiols, and the particle size was found to be nearly the same for both molecules. The synthesis was dependent on heating conditions and the best results were obtained when the temperature was between 180 and 200 degrees C. Addition of complexation agents such as acetyl acetone or triethylamine to the solvent did not change the product distribution significantly.     

Coordination chemistry of trivalent and pentavalent organoarsenic heterocyclic dithiocarbamate derivatives: synthesis and characterization

A series of diphenylarsenic(III) and triphenylarsenic(V) derivatives of heterocyclic dithiocarbamates of the type: and [where X = >?CH₂ (Pipdtc), >CH–CH₃ (4-MePipdtc), >O (Morphdtc), >N-CH₃ (N-MePzdtc), and?>?NH (Pzdtc)] [n?=?1 or 2] have been synthesized by reactions of diphenylarsenic(III) chloride and triphenylarsenic(V) dibromide with the sodium salt of heterocyclic dithiocarbamates in 1?:?1 and 1?:?2?M ratios, respectively, in refluxing benzene. All these newly synthesized compounds have been characterized by their elemental analyses, molecular weight measurements, and ESI mass studies. Structures of the compounds have been proposed on the basis of IR, ¹H, and ¹³C NMR spectral data which suggest anisobidentate mode of bonding.     

Diels-Alder reactions of trifluoromethyl alkenes with 5-ethoxyoxazoles: synthesis of trifluoromethylated pyridine derivatives

Cycloaddition reactions between 5-ethoxyoxazole derivatives [2,4-dimethyl 5-ethoxyoxazole and 4-methyl 5-ethoxyoxazole] and various trifluoromethyl alkenes [ethyl 4,4,4-trifluorocrotonate CF₃CHCHCO₂Et, 3,3,3-trifluoro 1-(phenylsulfonyl)-1-propene CF₃CHCHSO₂Ph and 2-(trifluoromethyl) propenoic acid CF₃(HO₂C)CCH₂] gave several trifluoromethyl-substituted pyridine systems in moderate yield (20-56%). Their structures were determined by multinuclear NMR techniques including ¹H-¹³C HETCOR spectroscopy.     

Synthesis of macrocycles that inhibit protein synthesis: stereochemistry and structural based studies on sanguinamide B derivatives

We report the synthesis of seven new sanguinamide B (SanB) analogues. Substitution of amino acids along the backbone of SanB and testing in HCT-116 colon cancer cell lines identified new biologically active SanB derivatives. These compounds establish a structure–activity relationship and show that a Cbz-lysine moiety is important for biological activity. We also identified the most effective stereochemistry at each position around the molecule. The biological activity of the macrocycle is extremely sensitive to stereochemistry and amino acid placement.