Studies on Amine Oxide Rearrangement: Synthesis of Pyrrolo[3,2‐c][1]benzothiopyran‐4‐one

A methodology, based on tandem [2,3] and [3,3] sigmatropic rearrangement, has been described for the synthesis of hitherto unreported, potentially bioactive pyrrolo[3,2‐c][1]benzothiopyran‐4‐ones (6a–g) derivatives.     

Synthesis of 3‐Substituted 2‐Thioxo‐2,3‐dihydro‐1H‐benzofuro[3,2‐ d ] pyrimidin‐4(1H)‐ones

With the purpose of searching for new biologically active compounds, a method of synthesis of new heterocyclic systems [3‐alkyl(aryl)‐2‐thioxo‐2,3‐dihydro‐1H‐benzofuro[3,2‐d]pyrimidin‐4(1H)‐ones] has been developed. The method is based on the interaction of ethyl 3‐isothiocyanato‐1‐benzofurane‐2‐carboxylate in 2‐propanol with amines in the presence of an equimolecular quantity of triethylamine.     

Regioselective Synthesis of 2H‐Benzothiopyrano[3,2‐c]quinolin‐7(8H)‐ones by Tri‐n‐butyltinhydride–Mediated Radical Cyclization

A number of hitherto unreported 2H‐benzothiopyrano[3,2‐c]quinolin‐7(8H)‐ones have been regioselectively synthesized in 90–96% yield by tri‐n‐butyltinhydride–AIBN–mediated radical cyclization from 4‐(2′‐bromothioarylmethyl)‐1‐methylquinolin‐2(1H)‐ones and their corresponding sulfones. 4‐(2′‐Bromothioarylmethyl)quinolin‐2(1H)‐ones were in turn prepared from 4‐bromomethylquinolin‐2(1H)‐one and o‐bromothiophenols by refluxing in acetone in the presence of anhydrous K₂CO₃. These were converted to the corresponding sulfones by oxidation with two equivalents of m‐CPBA in refluxing dichloromethane for 1 h.     

Glycosylation of 4‐Aryl‐1‐thioxo[1,2,4] triazolo[4,3‐a] quinazolin‐5(4H)‐one

Reaction of 4‐aryl‐1‐thioxo [1,2,4] triazolo [4,3‐a] quinazolin‐5 (4H)‐ones (2a,b) with acetylated glycosyl bromides 3a–c under alkaline conditions afforded the corresponding S‐glycoside derivatives 4, 5 and N‐glycoside derivatives 6, 7. Oxidation of S‐glycosyl derivatives 4, 5 with m‐chloroperbenzoic acid yielded the corresponding sulphones 8, 9, whereas the N‐glycosyl derivatives 6, 7 yielded 1‐oxo derivatives 10, 11. However their O‐deacetylation with sodium methoxide in methanol caused cleavage of the S‐glycosyl residue and gave N ²‐glycosylated analogues 12, 13, 14 and 15.     

Synthesis of [125I]‐, [2H]‐, and [3H]‐Labeled 3‐Iodothyronamine (T1AM)

3‐Iodothyronamine (T₁AM) is a novel metabolite of thyroid hormone. In HEK‐293 cells expressing an orphan G‐protein coupled receptor, the trace amine receptor, T₁AM, potently increased cAMP accumulation. In mice, T₁AM rapidly induced hypothermia and bradycardia within minutes of administration. These results suggest the existence of a new signaling pathway, the stimulation of which leads to rapid physiological and behavioral consequences. Isotope‐labeled T₁AM derivatives would be useful to study the biology and pharmacology of T₁AM. Herein we describe efficient syntheses of [¹²⁵I]‐, [²H]‐, and [³H]‐T₁AM.     

Microwave‐Assisted Rapid and Straightforward Synthesis of Novel 6‐(Aroxymethyl)‐2‐aryl‐6,7‐dihydropyrazolo[5,1‐c][1,4]oxazin‐4‐one Derivatives

A series of novel 6‐(aroxymethyl)‐2‐aryl‐6,7‐dihydropyrazolo[5,1‐c][1,4] oxazin‐4‐one derivatives was synthesized from ethyl 3‐aryl‐1H‐pyrazole‐5‐carboxylate and 2‐aryloxymethylepoxide by a microwave‐assisted, one‐step method in good yields. The microwave‐assisted reaction of ethyl 3‐aryl‐1H‐pyrazole‐5‐carboxylate and 2‐aryloxymethylepoxide proceeds with higher regioselectivity and is more economical and environmentally friendly in contrast to the normal intramolecular esterification route. A tandem mechanism of the reaction was proposed.     

Microwave‐Assisted Synthesis of 10‐(Phthalimidoalkyl)‐halosubstitutedpyrido [3,2‐b][1,4]‐benzothiazine in Dry Media

N‐Alkylation of 10H‐9‐fluoropyrido[3,2‐b][1,4]‐benzothiazine 5a, 10H‐7‐fluoropyrido[3,2‐b][1,4]‐benzothiazine 5b, and 10H‐7‐chloropyrido[3,2‐b][1,4]‐benzothiazine 5c with different N‐(bromoalkyl)phthalimides using anhydrous K₂CO₃ and tetrabutylammonium bromide (TBAB) under dry conditions with microwave irradiation leads to the formation of 10‐(phthalimidoalkyl)‐halosubstitutedpyrido[3,2‐b][1,4]‐benzothiazine (6a–f) along with some unidentified product. Compound 5a is a new azaphenothiazine derivative and was obtained from hitherto unknown 2‐acetylamino‐3‐fluorophenyl‐3′‐nitro‐2′‐pyridylsulfide 4a via Smiles rearrangement. Compound 4a is required for the synthesis and has been prepared starting from 2‐amino‐3‐fluorobenzenethiol 1a in three steps.     

Synthesis of Tetrahydro‐2(1H)quinazolinones,Cyclopenta[d]‐2(1H)pyrimidinones,and Their Thioxo Analogs from 2‐Trifluoroacetyl‐1‐methoxycycloalkenes

A series of six (8)‐alkyl‐4‐trifluoromethyl‐5,6,7,8‐tetrahydro‐2(1H)quinazolinones, 4‐trifluoromethyl‐cyclopenta[d]‐2(1H)pyrimidinones, and their thioxo analogs from the reaction of five β‐alkoxyvinyl trifluoromethyl ketones, derived from alkylated cyclohexanones and cyclopentanone with urea and thiourea, is reported. The reactions were carried out in a single step in propan‐2‐ol as solvent and boron trifluoride diethyl etherate as catalyst in 18–65% yield.     

Synthesis of Functionalized Pyrano[3,2‐c]pyridines and Their Transformations to 4‐Hydroxy‐3[(1E)‐N‐hydroxyalkanimidoyl]pyridones

Reaction of 4‐hydroxy‐6‐methyl‐2(1H)‐pyridones 1a and 4‐hydroxy‐1,6‐dimethyl‐2(1H)‐pyridones 1b with diethyl malonates 2a–e leads to the formation of pyrano[3,2‐c]pyridines 4a–j. Degradation of 4a–i affords the corresponding ketones 6a–i. Condensation of ketones 6a–i with hydroxyl amine or phenyl hydrazine hydrochloride is described.     

Convenient Synthesis of Substituted 5‐(Hydroxymethyl)‐8‐methyl‐3‐(4‐phenylquinazolin‐2‐yl)‐2H‐pyrano[2,3‐c]pyridin‐2‐ones

Abstract

Interaction of 2‐imino‐2H‐pyrano[2,3‐c]pyridin‐3‐carboxamide with substituted 2‐aminobenzophenones proceeds via recyclization mechanism leading to substituted 3‐(4‐arylquinazolyn‐2‐yl)‐2H‐pyrano[2,3‐c]pyridin‐2‐ones. Their reaction with acetic anhydride affords the O‐acylation products.     

Synthesis of Fused Tetrazolo[1,5‐c] pyrrolo[3,2‐e]pyrimidines and Their Reductive Conversion to New 4‐Aminopyrrolo[2,3‐d]pyrimidines

Some new 7,9‐substituted 7H‐1,2,3,4‐tetrazolo[1,5‐c]pyrrolo[3,2‐e]pyrimidines 5 have been synthesized either by diazotization of 4‐hydrazino‐5,7‐disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidines 4 obtained by hydrazinolysis of 4‐chloro‐5,7‐disubstituted 7H‐pyrrolo[2,3‐d]pyrimidines 3 or via a substitution reaction between 3 and sodium azide. 5,7‐Disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidin‐4(3H)‐ones 2 were obtained by cyclocondensation of 1,4‐disubstituted 2‐amino‐3‐cyanopyrroles 1 with formic acid, which, on chlorination using phosphorus oxychloride, afforded 3. 2‐Amino‐3‐cyanopyrroles 1 were synthesized from the reaction between (2-bromo-1-(4-fluorophenyl) ethylidene) propanedinitrile and substituted aromatic amines under Gewald reaction conditions. A novel route for the synthesis of 4‐amino‐5,7‐disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidines 6 by the reductive ring cleavage of 5 has been reported.     

COMPLEX SALTS [Pd(NH3)4][Pd(NH3)3NO2] [CrOx3]·H2O AND [Pd(NH3)4][Pd(NH3)3NO2] [CoOx3]·H2O AND SOLID SOLUTIONS [Pd(NH3)4] [Pd(NH3)3NO2][CoOx3]x[RhOx3]1–x·H2O : PROMISING PRECURSORS FOR POROUS NANOALLOYS

Journal of Structural Chemistry - New complex salts [Pd(NH3)4][Pd(NH3)3NO2][CrOx3]·H2O I, [Pd(NH3)4][Pd(NH3)3NO2][CoOx3]·H2O II, and a series of solid solutions...     

Synthesis and Antimicrobial Activity of 1‐[(Substituted Carbamoyl)Amino]‐1H,3H‐1λ5‐[1,3,2]oxazaphospholo[3,4‐a]benzimidazol‐1‐ones

1‐[(Substituted carbamoyl)amino]‐1H,3H‐1λ⁵‐[1,3,2]oxazaphospholo[3,4‐a]benzimidazol‐1‐ones were synthesized by reacting benzimidazole 2‐methanol (4) with different chlorides of carbamidophosphoric acids (3) in the presence of triethylamine at 40–45°C. Their ¹H, ¹³C, and ³¹P NMR spectral data were discussed. The title compounds were tested for their activity against the fungi Aspergillus niger and Fusarium solani and bacteria Staphylococcus aureus and Escherichia coli. These compounds showed moderate antibacterial activity when compared with antifungal activity.     

Synthesis of Ethyl 8‐Aryl‐8‐hydroxy‐3‐oxo‐8H[1,2,4]oxadiazolo‐[3,4‐c][1,4]thiazine‐5‐carboxylates by Ring‐Expansion Rearrangement

The title compounds were prepared by the ring–ring interconversion of ethyl 5‐nitroso‐6‐arylimidazo[2,1‐b]thiazole‐3‐carboxylates with hydrochloric acid. The effect of electron‐withdrawing substituent in the thiazole ring on the general applicability of the ring–ring interconversion has been also evaluated.     

Synthesis of （1H）—3,4—Dithydropyrrolo[2,1—c][1,4]oxazin—1—one Derivatives

In search of new anti-inflammatory and analgesic agents,(1H)-3,4-dihydro-pyrrolo [2,1-c][1,4]oxazin-1-one(3) and its acyl derivatives were designed and prepared .Compound 3 was prepared by treatment of methyl 1-(2-bromoethyl) pyrrole-2-carboxylate with silver oxide and its derivatives were obtained by Friedel-Carftes reaction.Nine of 6-acyl derivatives of compound 3 were prepared.     

Acronycine Analog: New Selective Synthesis of 6‐Methoxy‐3,3‐dimethyl‐3H,7H‐pyrano[2,3‐c]xanthen‐7‐one

A new, convenient, and selective route to the dimethylpyrano[2,3‐c]xanthen‐7‐one, analog of acronycine, via aromatization and dehydrogenation reactions from the corresponding saturated hexahydro intermediate is described.     

Facile One‐Pot Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐one Catalyzed by Zn(NH2SO3)2

An efficient synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones (DHPMS) from aromatic aldehydes, β‐keto ester, and urea (or thiourea) in refluxing ethanol using zinc sulfamate as a catalyst is first described here. Compared to the classical Biginelli reaction, this new method consistently has the advantages of good yields (76–96%), short reaction time (2–5 h), no corrosion of equipment, ease of manipulation, and low‐cost catalyst.     

Synthesis of 2,3‐Dihydro‐4H‐furo[3,2‐c] chromen‐4‐ones and 2,3‐Dihydronaphtho[2,3‐b]furan‐4,9‐diones by the Radical Cyclizations of Hydroxyenones with Electron-Rich Alkenes using Manganese(III) Acetate

We have obtained dihydrofurans 3a–j in the radical cyclization of 4‐hydroxycoumarin 1a and 2‐hydroxy‐1,4‐naphtoquinone 1b with electron rich alkenes 2a–i by manganese(III) acetate. Methods A and B, which have different molar ratios were studied comparatively in these reactions, and we observed that method B (molar ratio 2:1:3) gave the best results. Treatment of 4‐hydroxycoumarin 1a and electron rich alkenes 2a–e gave 2,3‐dihydro‐4H‐furo[3,2‐c]chromen‐4‐ones 3a–e in 36–86% yields by the method B. Under the same conditions, the reactions of 2‐hydroxy‐1,4‐naphtaquinone 1b with conjugated alkenes 2b and 2f–i afforded 2,3‐dihydronaphtho[2,3‐b]furan‐4,9‐diones 3f–j in an excellent yields.     

Synthesis,Crystal and Molecular Structures of [Co(MH)2(Thio)2][BF4] · H2O and [Co(DH)2(NH3)2][BF4]

Crystal structures of [Co(MH)₂(Thio)₂][BF₄] · H₂O (I) and [Co(DH)₂(NH₃)₂][BF₄] (II), where MH^– is H₃C–C(NOH)–C(NO^–)–H and DH^– is H₃C–C(NOH)–C(NO^–)–CH₃, were determined by X-ray diffraction. The crystals are monoclinic, space group C2/c, unit cell parameters (for I and II, respectively): a = 22.018(2) Å, b = 7.943(1) Å, c = 11.681(1) Å, = 92.68(1)° and a = 21.436(2) Å, b = 6.400(2) Å, c = 12.389(2) Å, = 113.13(1)°. In both cases, the Co(III) coordination polyhedron is a centrosymmetrical trans-octahedron, N₄S₂ for I and N₆ for II. In the crystals of I and II, the complex cations and the outer-sphere [BF₄]^– anions (and the crystal water molecules in I) form elaborate hydrogen bonding system.     

Synthesis of New (4‐Acetonylidene‐2,6,8,9‐tetramethyl‐7H‐imidazo[1,5,4‐e,f][1,5]benzodiazepine) Derivatives

Imidazobenzodiazepine derivatives were obtained by cyclization of the condensation products 7‐amino‐2,5,6‐trimethylbenzimidazole with acetylacetone and ethyl acetoacetate. By careful examination of spectroscopic data and the open‐chain intermediate isolation, we have identified the formed compound structure.