Reaction of Some 2‐Quinolone Derivatives with Phosphoryl Chloride: Synthesis of Novel Phosphoric Acid Esters of 4‐Hydroxy‐2‐quinolone

3‐Chloroquinoline‐2,4‐diones do not react with phosphoryl chloride, however, 2,4‐dichloroquinolines and/or 4‐chloroquinolin‐2‐ones are formed in the presence of N,N‐dimethylaniline. Along with these compounds, small quantities of novel dihydrogen phosphates of 4‐hydroxyquinolin‐2‐ones were isolated. We outline a simple procedure that allows for the preparation of these compounds in moderate to good yields. All compounds were characterized by ¹H and ¹³C NMR, IR, EI‐MS, and ESI‐MS spectroscopy, and in select cases by ³¹P NMR spectroscopy.     

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.     

Selenium‐Containing Heterocycles from Isoselenocyanates: 4‐Methylselenazole Derivatives from the Reaction with Malononitrile and Propargyl Chloride

Aryl isoselenocyanates 1 react with malononitrile ( 6a ) and propargyl chloride ( 8 ) in DMF in the presence of Et₃N to give the corresponding 2‐(3‐aryl‐2,3‐dihydro‐4‐methyl‐1,3‐selenazol‐2‐ylidene)malononitriles 12 as major products. The analogous reaction takes place with benzoylacetonitrile ( 6f ) instead of 6a . In some cases, the corresponding noncyclic 2‐[(arylamino)(prop‐2‐ynylselanyl)methylidene]malononitriles 9 were obtained as minor products. The structures of 9e and 11a have been established by X‐ray crystallography.     

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.     

Synthesis of Some Novel 3‐Substituted Indole Derivatives Using Polyamine Functionalized Heterogeneous Catalyst

In present work, we have described the use of polyamine solid supported GN3 as catalyst in organic transformations using 1H‐indole‐3‐carbaldehyde. To the best of our knowledge, reports for the synthesis of chromen substituted at 3C position of indole are extremely rare in the literature. The polyamine functionalized immobilized silica (GN3) was found to be an excellent catalyst for synthesis of novel 2‐amino‐4‐(1H‐indol‐3‐yl)‐5‐oxo‐4,5‐dihydropyrano[3,2‐c]chromene‐3‐carbonitrile derivatives and Knoevenagel condensation. Catalyst GN3 was able to furnish excellent yield for a wide range of products. Moreover, the catalyst was reusable and reused for several times without loss of its catalytic activity.     

One‐Pot Synthesis of 3‐Substituted 3,4‐Dihydro‐1,2,3‐benzotriazine Derivatives Based on the Reaction of o‐Bromobenzyl Azides with Butyllithium

An efficient one‐pot procedure for the preparation of 3‐substituted 3,4‐dihydro‐1,2,3‐benzotriazines 2, 3 , and 4 from o‐bromobenzyl azides 1 is described. The reaction of these azides with BuLi in THF at ?78° generates o‐lithiobenzyl azides via the Br/Li exchange. These lithium compounds immediately undergo intramolecular cyclization to give the corresponding (dihydro‐1,2,3‐benzotriazinyl)lithium intermediates, which are trapped with a variety of acylating agents or BnBr at N(3) exclusively to provide the desired products in moderate to good yields.     

Reaction of 3‐Hydroxyquinoline‐2,4‐diones with Isocyanates and Thermally Induced Transformation of the Reaction Products

3‐Hydroxyquinoline‐2,4‐diones 1 react with isocyanates to give novel 1,2,3,4‐tetrahydro‐2,4‐dioxoquinolin‐3‐yl (alkyl/aryl)carbamates 2 and/or 1,9b‐dihydro‐9b‐hydroxyoxazolo[5,4‐c]quinoline‐2,4(3aH,5H)‐diones 3 . Both of these compounds are converted, by boiling in cyclohexylbenzene solution in the presence of Ph₃P or 4‐(dimethylamino)pyridine, to give 3‐(acyloxy)‐1,3‐dihydro‐2H‐indol‐2‐ones 8 . All compounds were characterized by IR, and ¹H‐ and ¹³C‐NMR spectroscopy, as well as by EI mass spectrometry.     

Asymmetric Synthesis of Chiral α‐Substituted Mercaptoglycine Derivatives via α‐Sulfenylation of Ni(II) Complex of Glycine and S‐Substituted 4‐Methylbenzenesulfonothioate

The asymmetric α ‐sulfenylation of Ni(II ) complex of glycine with S ‐substituted 4‐methylbenzenesulfonothioate is reported. Due to the mild and simple reaction conditions, this asymmetric reaction is compatible with various functional groups.     

Synthesis of Some Bromomethyl‐ and (4‐Bromomethyl)phenyl‐Derivatives of 1,4,8,11 Tetraaza[14] annulene and Their Corresponding Sulfanylmethylene‐Derivatives Using 3‐Substituted Trimethinium Salts

Four new 6,13‐di(bromomethyl)‐ and di[(4‐bromomethyl)phenyl]1,4,8,11‐tetraaza[14]annulene derivatives C , D , E , F were synthesized using the condensation reaction of the correspondingly substituted vinamidinium salts with aromatic amines in acetonitrile/acetic acid. The reaction of these annulenes with thiourea leads to the corresponding thiol derivatives G and H . The UV/vis spectral behavior of compounds C , D , E , F , G , H was examined in DMSO. Elemental analysis, IR, ¹H‐NMR, ¹³C‐NMR, and mass spectral data confirm the molecular structure of the newly synthesized compounds.     

Synthesis of β‐Substituted γ‐Aminobutyric Acid Derivatives through Enantioselective Photoredox Catalysis

β‐Substituted chiral γ‐aminobutyric acids feature important biological activities and are valuable intermediates for the synthesis of pharmaceuticals. Herein, an efficient catalytic enantioselective approach for the synthesis of β‐substituted γ‐aminobutyric acid derivatives through visible‐light‐induced photocatalyst‐free asymmetric radical conjugate additions is reported. Various β‐substituted γ‐aminobutyric acid analogues, including previously inaccessible derivatives containing fluorinated quaternary stereocenters, were obtained in good yields (42–89 %) and with excellent enantioselectivity (90–97 % ee). Synthetically valuable applications were demonstrated by providing straightforward synthetic access to the pharmaceuticals or related bioactive compounds (S)‐pregabalin, (R)‐baclofen, (R)‐rolipram, and (S)‐nebracetam.     

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.     

Synthesis,Voltammetric and Analytical Applications of Some Fluorine Substituted Spirosteroidalthiazolidin‐4‐one Derivatives of Sulfa Drugs

A new 5‐arylidene‐4‐oxo‐(sulfonamoyl phenyl)‐spiro[thiazolidinone‐2,2′‐steroids] series (7–10) was prepared by condensation of sulfanilamide, sulfapyridine and sulfadiazine sulfa drugs with testosterone, epiandrosterone and progesterone steroids, respectively. The resultant imino derivatives 1–3 upon cycloaddition with thioacetic acid in dry 1,4‐dioxane afforded 3‐sulfo‐namoylphenylspiro[4‐oxo‐thiazolidin‐2,2′steroids] (4–6). The latter compounds (4–6) upon condensation with p‐fluorobenzaldehyde in ethanol‐piperidine yielded the corresponding 4‐fluoroarylidene derivatives 7, 8 & 9, respectively. All the newly synthesized compounds were confirmed by UV, IR, ¹H NMR, ¹³C NMR, mass spectral data, elemental analysis and molecular weight determination. In vitro antimicrobial screening of some of the synthesized compounds showed good antimicrobial activities towards some pathogenic Gram‐positive, Gram‐negative bacteria and fungi vs. piperacillin and mycostatine antibiotics as standard antibacterial and antifungal agents, respectively. The voltammetric behavior of two newly spirothiazolidinone steroids ( 2a & 5a ) was critically studied. Compound 5a physically immobilized polyurethane foam solid sorbent was successfully used for removal and/or separation of bismuth(III) from water.     

Synthesis of Novel Substituted 2‐Lactosylthiothieno[2,3‐d]pyrimidin‐4(3H)‐one Derivatives

The title compounds substituted 2‐lactosylthiothieno[2,3‐d]pyrimidin‐4‐ones 6 were synthesized by the glycosyl reaction and alcoholysis reaction of substituted 2‐thioxo‐thieno[2,3‐d]pyrimidin‐4‐ones 4 ,which is formed by the base catalytic and acetic acidify reaction of amino esters 2 with alkyl or arylisothiocyanates and hepta‐O‐acetyl‐lactosyl bromide in good yields. All of the compounds were confirmed by NMR, ESI‐MS, and elemental analysis.     

Substituted 4‐Oxo‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic Esters by a Tandem Imine Addition‐SNAr Reaction

A tandem imine addition‐S_NAr annulation reaction has been developed as a new approach to the synthesis of 4‐oxo‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic esters. A series of these structures has been generated by reacting selected imines with tert‐butyl 2‐fluoro‐5‐nitrobenzoylacetate. Structural variations in the final products are accomplished by changing the substituents on the imine and the alkyl group of the ester. The title compounds are isolated as their enols in 55–97% yield without the need for added base or catalysts. The synthesis of the starting materials as well as mechanistic studies and further synthetic conversions of the products are presented.     

Synthesis and Herbicidal Evaluation of 3‐N‐Substituted Amino‐6‐benzyloxypyridazine Derivatives

A variety of 3‐N‐substituted amino‐6‐benzyloxypyridazine derivatives were designed and synthesized in satisfactory yields. Their structures were confirmed by IR, ¹H‐NMR, and elemental analysis; compound 5j was further determined by X‐ray diffraction crystallography. Their herbicidal activities were evaluated through barnyard grass and rape cup tests in laboratory bioassays. Most of the title compounds 5 displayed moderate herbicidal activities against the dicotyledonous plant Brassica campestris L. The most active compounds in the laboratory were also evaluated in the greenhouse.