Synthesis and Cytotoxicity of 6‐Pyrrolidinyl‐2‐(2‐Substituted Phenyl)‐4‐Quinazolinones

In our continuing search for potential anticancer candidates, 2‐(3‐methoxyphenyl)‐6‐pyrrolidinyl‐4‐quinazolinone ( JJC‐1 ) was selected as the lead compound. Starting 5‐pyrrolidinyl‐2‐aminobenzamide was prepared using standard methodology from 5‐chloro‐2‐nitrobenzoic acid by reaction with SOCl₂, NH₃, pyrrolidine, and H₂. The starting benzamide then was reacted with 2‐substituted benzaldehyde or benzoyl chloride in N,N‐dimethylacetamide (DMAC) in the presence of NaHSO₃ at 150 °C. Thermal cyclodehydration/dehydrogenation gave the target 6‐pyrrolidinyl‐2‐(2‐substituted phenyl)‐4‐quinazolinones ( 15–22 ). These target compounds were assayed for their cytotoxicity in vitro against six cancer cell lines, including human monocytic leukemia cells (U937), mouse monocytic leukemia cells (WEHI‐3), human hepatoma cells (HepG2, Hep3B) and human lung carcinoma cells (A549, CH27). Most of them exhibited significant cytotoxic effect toward U937 and WEHI‐3 cells, with EC₅₀ values ranging from 0.30 to 10.10 μM. Compound 19 was investigated further for its action mechanisms. Preliminary findings indicated that compound 19 induced G2/M arrest and apoptosis on U937 cells.     

Synthesis of Some Novel Phenyl Substituted Oxothiazolidin- 1’’,3’’,4’’-thiadiazolo-[3’,4’-b]thiazoline of 3β-Substituted Cholestane

Three title compounds 4a—4c have been synthesized by the cyclodehydration of 1’-benzylidine-4’-(3β-substituted-5α-cholestane-6-yl)thiosemicarbazones 2a—2c with thioglycolic acid followed by the treatment with cold conc. H2SO4 in dioxane. The compounds 2a—2c were prepared by condensation of 3β-substituted-5α-cholestan- 6-one-thiosemicarbazones 1a—1c with benzaldehyde. These thiosemicarbazones 1a—1c were obtained by the reaction of corresponding 3β-substituted-5α-cholestan-6-ones with thiosemicarbazide in the presence of few drops of conc. HCl in methanol. The structures of the products have been established on the basis of their elemental, analytical and spectral data.     

Preparations of 4‐Substituted 3‐Carboxypyrazoles

The scopes of three synthetic methods reported for the preparation of an array of 3‐pyrazolecarboxylates featuring substituents on position 4 were investigated. The first one is based on the potassium permanganate oxidation of methylpyrazoles. The second starts with the condensation between DMF dimethylacetal and ethyl pyruvate and is followed by the addition of hydrazine hydrochloride. The last one makes use of the cycloaddition of diazomethane on acrylate esters followed by a bromine‐based oxidative rearrangement into 4‐substituted 3‐pyrazole esters.     

One‐Pot Synthesis of 4‐Substituted 3,4‐Dihydro‐3‐methoxyisocoumarins via Carboxylation of α‐Substituted 2‐Lithio‐β‐methoxystyrenes with Carbon Dioxide

A new type of isocoumarins (=1H‐isochromen‐1‐ones=1H‐2‐benzopyran‐1‐ones), 4‐substituted 3,4‐dihydro‐3‐methoxyisocoumarins 2 , can be obtained by a one‐pot process from α‐substituted 2‐bromo‐β‐methoxystyrenes 1 . Thus, lithium 2‐(1‐aryl(or methyl)‐2‐methoxyethenyl)benzoates are conveniently generated via the Br/Li exchange between 1 and BuLi, followed by the action of CO₂ on the resulting α‐substituted 2‐lithio‐β‐methoxystyrenes. Upon treating with concentrated HCl at room temperature, these lithium benzoates undergo lactonization to provide the desired 3,4‐dihydroisocoumarins 2 in relatively good yields.     

Synthesis of 3‐Substituted Benzpyrid‐4‐imino‐2‐oxime Derivatives

Pyrazolone, Isoxazolone, Pyrimidinone, Pyrimidinothione, thiazolidinone and β‐lactam incorporating 2‐oximino benzpyrid‐4‐one derivatives have been synthesized by cyclocondensation addition reaction and cycloaddition of hydrazine hydrate, phenyl hydrazine, hydroxylamine, urea, thiourea, mercapto acetic acid, and chloroacetylchloride, respectively.     

ECEC and ECE‐Type Mechanisms in Electrochemical Oxidation of 4‐Substituted Catechols in the Presence of 4‐Hydroxy‐6‐methyl‐2‐pyrone

Electrochemical oxidation of 3,4‐dihydroxybenzoic acid ( 1 ) and 4‐tert‐butylcatechol ( 5 ) in the presence of 4‐hydroxy‐6‐methyl‐2‐pyrone ( 2 ) as nucleophile in aqueous solution has been studied using cyclic voltammetry and controlled‐potential coulometry. The results indicate that 1 via Michael reaction under electro‐decarboxylation reaction converts to heterocyclic compound 4 , and the quinone derived from 4‐tert‐butylcatechol ( 5 ) participates in Michael reaction with 2 and through an ECE mechanism converts to the corresponding o‐quinone ( 6a ). The electrochemical synthesis of 4 and 6a has been successfully performed in an undivided cell.     

Electrocarboxylation of Acetophenone to 2‐Hydroxy‐2‐phenylpropionic Acid in the Presence of CO2

Electrocarboxylation of acetophenone with CO₂ to obtain 2‐hydroxy‐2‐phenylpropionic acid was carried out in acetonitrile solution containing 0.1 mol·L^?1 tetraethylammonium bromide. Influences of the nature of the electrodes, the working potential, the passed charge and the concentration of acetophenone on the electrocarboxylation were studied. After optimizing the synthetic parameters, the maximal isolated yield reached 73.0% on Mg‐stainless steel couple electrodes under potentiostatic electrolysis until 2.2 F·mol^?1 of charge was passed at 25 °C. The reduction of acetophenone was studied by cyclic voltammetry and the mechanism has been proposed on the basis of the results.     

K2CO3/H2O in [omim][BF4] Ionic Liquid: A Green Medium for Efficient Room‐Temperature Synthesis of N‐Substituted 1,4‐Benzoxazin‐3‐ones

A medium consisting of K₂CO₃ and H₂O in [omim][BF₄] ionic liquid (IL) was used to synthesize N‐substituted 2H‐benzo[b][1,4]oxazin‐3(4H)‐one derivatives from their corresponding o‐aminophenols and 2‐bromoalkanoates. As a result, chemoselective formation of benzoxazinones in high yields has been observed at room temperature. After the reactions and separation of the products, the IL was recovered and successfully reused in subsequent reactions without significant loss of activity.     

Synthesis of (2S)‐2‐(Benzoylamino)‐3‐(heteroaryl)propyl Benzoates

(3E,5S)‐1‐Benzoyl‐5‐[(benzoyloxy)methyl]‐3‐[(dimethylamino)methylidene]pyrrolidin‐2‐one ( 9 ) was prepared in two steps from commercially available (S)‐5‐(hydroxymethyl)pyrrolidin‐2‐one ( 7 ) (Scheme 1). Compound 9 gave, in one step, upon treatment with various C,N‐ and C,O‐1,3‐dinucleophiles 10 – 18 , the corresponding 3‐(quinolizin‐3‐yl)‐ and 3‐(2‐oxo‐2H‐pyran‐3‐yl)‐substituted (2S)‐2‐(benzoylamino)propyl benzoates 19 – 27 (Schemes 1 and 2).     

Investigation of the Reaction of Gold(III) with 2‐[2‐(4‐Dimethylamino‐Phenyl)‐Vinyl]‐1,3,3‐Trimethyl‐3H‐Indolium. Application for Determination of Gold

A new, simple, rapid, sensitive, efficient and low‐cost spectrophotometric procedure for the determination of gold was developed. The method is based on the reaction of [AuCl₄]^? with 2‐[2‐(4‐dimethylaminophenyl)‐vinyl]‐1,3,3‐trimethyl‐3H‐indolium reagent to form a colored ion associate extractable by various organic solvents. The molar absorptivity of the ion associates is in the range (5.7–9.2) × 10⁴ L mol^?1 cm^?1 depending on the extractant. Butyl acetate was chosen as the extractant. The optimum reaction conditions were established: pH 2–4, concentration of the dye reagent (0.8–1.5) × 10^?4 mol L^?1. The determination of gold is not hindered even by a 1000‐fold concentration of Ni and Co; a 500‐fold concentration of Pb and Zn; a 100‐fold concentration of Bi, Cu, Cd, Pt, Rh and Ru; or a 20‐fold concentration of Ag. The established method was applied to the determination of gold in model samples and enriched polymetallic ores.     

Activation parameters of transesterification of 4-nitrophenyl acetate in the presence of K2CO3 in DMF

The activation parameters for the reactions of 4-nitrophenyl acetate with 4-chlorophenol and benzenethiol in the presence of potassium carbonate in dimethylformamide were determined. Depending on the substrate structure, the enthalpy and entropy of activation decrease in going from 4-nitrophenyl acetate to 4-nitrophenyl benzoate, while the Gibbs energy of activation increases.     

Heterodinukleare Komplexe: Synthese und Kristallstrukturen von [RuRh(μ‐CO)(CO)4(μ‐PtBu2)(tBu2PH)], [RuRh(μ‐CO)(CO)3(μ‐PtBu2)(μ‐Ph2PCH2PPh2)] und [CoRh(CO)4(μ‐H)(μ‐PtBu2)(tBu2PH)]

Heterobinuclear Complexes: Synthesis and X‐ray Crystal Structures of [RuRh(μ‐CO)(CO)₄(μ‐P^tBu₂)(^tBu₂PH)], [RuRh(μ‐CO)(CO)₃(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)], and [CoRh(CO)₄(μ‐H)(μ‐P^tBu₂)(^tBu₂PH)] [Ru₃Rh(CO)₇(μ₃‐H)(μ‐P^tBu₂)₂(^tBu₂PH)(μ‐Cl)₂] ( 2 ) yields by cluster degradation under CO pressure as main product the heterobinuclear complex [RuRh(μ‐CO)(CO)₄(μ‐P^tBu₂)(^tBu₂PH)] ( 4 ). The compound crystallizes in the orthorhombic space group Pcab with a = 15.6802(15), b = 28.953(3), c = 11.8419(19) Å and V = 5376.2(11) ų. The reaction of 4 with dppm (Ph₂PCH₂PPh₂) in THF at room temperature affords in good yields [RuRh(μ‐CO)(CO)₃(μ‐P^tBu₂)(μ‐dppm)] ( 7 ). 7 crystallizes in the triclinic space group P 1 with a = 9.7503(19), b = 13.399(3), c = 15.823(3) Å and V = 1854.6 ų. Moreover single crystals of [CoRh(CO)₄(μ‐H)(μ‐P^tBu₂)(^tBu₂PH)] ( 9 ) could be obtained and the single‐crystal X‐ray structure analysis revealed that 9 crystallizes in the monoclinic space group P2₁/a with a = 11.611(2), b = 13.333(2), c = 18.186(3) Å and V = 2693.0(8) ų.     

On the Reaction Products of 4‐Substituted 3‐Pyridinesulfonamides with Some Benzenesulfonyl Chloride Derivatives

The reactions of 4‐substituted 3‐pyridinesulfonamides 1a , 1b , 1c , 1d , 1e with benzenesulfonyl chlorides 2a , 2b , 2c , 2d , 2e , 2f in acetonitrile were investigated. Depending on the structure of arylsulfonyl chlorides and the reaction conditions the following four types of products were obtained in good yields: 3‐sulfamoyl‐4‐R‐1‐arylpyridinium chlorides 3 , 4 , 5 , 6 , 7 , 8 ; 1,10‐bis(3‐nitrobenzenesulfonylimino)deca‐2,4,6,8‐tetraene‐2,9‐disulfonamides 9 , 10 , 11 , 12 ; 1‐substituted 1,4‐dihydro‐4‐oxo‐3‐pyridinesulfonamides 13 , 14 ; and 4‐methoxy‐3‐[N‐(2,5‐dichlorophenyl)sulfonyl] sulfonamidates 15 and 16 . The mechanisms of these reactions were discussed.