Cascade synthesis of pyrido[3,2-a]indolizines by reaction of Kröhnke–Mukaiyama salts with malononitrile dimer

An efficient protocol for the synthesis of highly functionalized 2-aminoindolizines and pyrido[3,2-a]indolizines has been achieved via the reaction of N-RC(O)CH₂-2-chloropyridinium bromides with 2-amino-1,1,3-tricyanopropene in the presence of Et₃N. The reaction of N-allyl-2-chloropyridinium bromide with 2-amino-1,1,3-tricyanopropene in the presence of Et₃N gives 3-[1-allylpyridin-2(1Н)-ylidene]-2-aminoprop-1-ene-1,1,3-tricarbonitrile, which could be cyclized to give [2-amino-(2-amino-3-vinylindolizin-1-yl)methylene]malononitrile upon treatment with KOH–DMF.     

(Z)-Ethyl 2-phenyl-1-(2-vinylphenyl)vinylcarbamates. Part 1: Synthesis and preliminary studies on their divergent transformation into benzo[c]phenanthridines and 2-phenyl-1,4-naphthoquinones

Treatment of N-carbethoxy-1-benzylideneisoquinolines with LDA gives N-ethoxycarbonyl-1-amino-1-(2-vinylphenyl)-2-phenylethylenes, which can easily be transformed into N-carbethoxy-1-amino-2-phenylnaphthalenes. Bischler-Napieralski reaction of these latter compounds affords the corresponding benzo[c]phenanthridines, while their hydrolysis and subsequent oxidation constitutes a novel route to 2-phenyl-1,4-naphthoquinones.     

Reactions of 1-amino-2-nitroguanidine with 2-aryl(hetaryl)-1-nitro-1-ethoxycarbonyl(benzoyl)ethenes

Reactions of 1-amino-2-nitroguanidine with 2-aryl(hetaryl)-1-nitro-1-ethoxycarbonyl(benzoyl)-ethenes proceed via initial formation the aza-Michael product, are accompanied by liberation of nitroacetic ester (or nitroacetophenone), and result in N-aryl(hetaryl)methylidene-N-(2-nitroguanidino)amines.     

Stereoselective synthesis,solution structure and metal complexes of (1S,2S)-2-amino-1-hydroxyalkylphosphonic acids

The highly stereoselective synthesis of (1S,2S)-2-amino-1-hydroxyalkylphosphonic acids was achieved by addition of dimethyl phosphite to N-protected aminoaldehydes. Relative configuration and solution conformations of (1S,2S)-2-amino-1-hydroxy-alkylphosphonic acids (in D₂O) and their dimethyl esters (in CDCl₃ and CD₃OD) were established by means of NMR basing on the dependence between observed values of coupling constants (³J_HH, ³J_PC, ³J_HP) and corresponding dihedral angles. Potentiometric and spectroscopic methods were used for the evaluation of the structure of the complexes of (1S,2S)-2-amino-1-hydroxy-alkylphosphonic acids with Zn(II) and Cu(II) ions in aqueous solutions.     

Resolution of racemic 2-amino-1-butanol with immobilised penicillin G acylase

Racemic 2-amino-1-butanol has been resolved to obtain (S)-2-amino-1-butanol with >99% e.e. via enantioselective hydrolysis of its N-phenylacetyl derivative with penicillin G acylase immobilised on Eupergit C.     

Photochemical synthesis of 2-amino-1-hydroxy-9,10-anthraquinone-9-alkyl(aryl)imines

Irradiation of a mixture of 1-aryloxy-2-amino-9,10-anthraquinone and amines in benzene results in formation of the derivatives of 2-amino-1-hydroxy-9,10-anthraquinone-9-alkyl(aryl)imines in a high yield. 2-Amino-1-hydroxy-9,10-anthraquinone-9-aikylimines were shown by¹³C and¹⁵N NMR to exist predominantly in the enaminoquinoid form whereas 2-amino-1-hydroxy-9,10-anthraquinone-9-arylimines exist in the oxyimine form. Sunlight irradiation of the derivatives of 2-benzoylamino-9,10-anthraqumone-9-alkylimines results in formation of the photocyclization products — 4-benzoylaminoanthra-[9,1-d,e]-1,3-oxasinones-7.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 940–944, May, 1993.     

Syntheis of 2-aryloxy- and 2-arylalkoxy-1-(2-piperidyl)ethanols

The preparation and separation of diastereomeric pairs of a series of 2-aryloxy- and 2-arylalkoxy-1-(2-piperidyl)ethanols is reported. The erythro aminoalcohols were converted into threo isomers by thionyl chloride treatment of their N-acetyl derivatives and alkaline hydrolysis.     

Synthesis and ring transformations of 1-amino-1,2,3,9a-tetrahydroimidazo[1,2-a]indol-2(9H)-ones

Heating 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolinium chloride in the presence of hydrazine bishydrate produces regioselectively the five-membered heterocycle 1-amino-1,2,3,9a-tetrahydro-9,9,9a-trimethylimidazo[1,2-a]indol-2(9H)-one. The assignment of the structure is based on extensive ¹H, ¹³C and ¹⁵N NMR spectroscopic studies. No ring-chain tautomerism of the 1-amino-1,2,3,9a-tetrahydroimidazo[1,2-a]indol-2(9H)-one was observed to open-chain hydrazides or the corresponding six-membered 1,2,10,10a-tetrahydro[1,2,4]triazino[4,3-a]indol-3(4H)-one. Further transformations of 1-amino-1,2,3,9a-tetrahydroimidazo[1,2-a]indol-2(9H)-one were performed by treatment with aromatic aldehydes, acid chlorides and isocyanates giving access to 40 novel hydrazones, N,N′-diacylhydrazines, N-acyl-N′-carbamoylhydrazines and 1,3,4-oxadiazoles.     

Synthesis of four enantiomers of 2-acetamido-1-hydroxypropylphosphonates

Enantiomerically pure diethyl 2-acetamido-1-hydroxypropylphosphonates were synthesised from N-[(R)-(1-phenylethyl)]aziridine-(2S)- and N-[(S)-(1-phenylethyl)]aziridine-(2R)-carboxaldehydes via phosphonylation followed by acetylation of the hydroxy groups and the simultaneous hydrogenolytic cleavage of the aziridine rings and the removal of the chiral auxiliaries. In addition, enantiomerically pure diethyl (1S,2R)- and (1R,2S)-2-amino-1-hydroxypropylphosphonates (the phosphonate analogues of isothreonine) were separated.     

Electrophilic cyclization of <Emphasis Type="Italic">N</Emphasis>-allyl(propargyl)-5-amino-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-4-carboxamides. Synthesis of 4-[(dihydro)oxazol-2-yl]-1<Emphasis Type="Italic">H</Emphasis>-pyrazol-5-amines

N-Allyl-5-amino-1H-pyrazole-4-carboxamides in reactions with polyphosphoric acid, with N-halosuccinimides in chloroform, and with (chlorosulfanyl)benzenes in nitromethane in the presence of lithium perchlorate underwent cyclization involving the N-allylamide fragment to give 4-[5-methyl(halomethyl)-4,5-dihydrooxazol-2-yl]-1H-pyrazol-5-amines and 2-(5-amino-1H-pyrazol-4-yl)-5-[(arylsulfanyl)methyl]-4,5-dihydro-1,3-oxazolium perchlorates, respectively. Analogous reactions of N-propargyl-5-amino-1H-pyrazole-4-carboxamides with polyphosphoric acid afforded 4-(5-methyloxazol-2-yl)-1H-pyrazol-5-amines, and with (chlorosulfanyl) benzenes, 2-(5-amino-1H-pyrazol-4-yl)-5-[(arylsulfanyl)methylidene]-4,5-dihydro-1,3-oxazolium perchlorates.     

Acetylation of 1-amino-2-aryloxy-4-hydroxy-9,10-anthraquinones. Cyclization of N-acetyl derivatives of 1-amino-2-aryloxy-4-hydroxy-9,10-anthraquinones into 4-aryloxy-6-hydroxy-3<Emphasis Type="Italic">H</Emphasis>-naphtho[1,2,3-<Emphasis Type="Italic">d,e</Emphasis>]quinoline-2,7-diones

Acetylation of 1-amino-2-aryloxy-4-hydroxy-9,10-anthraquinone qith acetic anhydride at 70–80°C in pyridine proceeded at the hydroxy group, and in acetic acid, at the amino group. Under more stringent conditions at 80–100°C products of N,N-diacetylation and N,N,O-triacetylation were obtained. The products of N-acetylation in basic media underwent cyclization into 4-aryloxy-6-hydroxy-3H-naphtho[1,2,3-d,e] quinoline-2,7-diones.     

Reaction of ketenes with N,N-disubstituted α-aminomethyleneketones. XII. Synthesis of N,N-disubstituted 4-amino-3-chloro-6-(2-methyl-l-propenyl) (2-phenylethenyl)-2H-pyran-2-ones

Cycloaddition of dichloroketene to N,N-disubstituted (E)-amino-5-methyl-1,4-hexadien-3-ones IV and (E,E)-1-amino-5-phenyl-1,4-pentadien-3-ones V occurred in moderate to good yield only in the case of aromatic N-substitution to give N,N-disubstituted 4-amino-3,3-dichloro-3,4-dihydro-6-(2-methyl-l-propenyl) (2-phenylethenyl)-2H-pyran-2-ones, which were dehydrochlorinated with DBN to afford in good yield N,N-disubstituted 4-amino-3-chloro-6-(2-methyl-propenyl)(2-phenylethenyl)-2H-pyran-2-ones. In the case of aliphatic N,N-disubstitution (dimethylamino group) of enaminones IV and V, the Cycloaddition led directly in low yield to 3-chloro-4-dimethylamino-6-(2-methyl-l-propenyl)(2-phenylethenyl)-2H-pyran-2-ones.     

Traceless solid-phase synthesis of 1,4-disubstituted-6-nitro-3,4-dihydro-1H-quinoline-2-ones

A traceless solid-phase route to 1,4-disubstituted-6-nitro-3,4-dihydro-1H-quinazolin-2-ones is described. N-Alloc-3-amino-3-(2-fluoro-5-nitrophenyl)propionic acid was tethered to Rink resin via its carboxylic group. The protected amine was coupled with an organic acid after Alloc-deprotection and the arylfluorine was displaced with a primary amine to generate a resin-bound aniline with two diversity points. The aniline was released via cleavage to produce the desired products in high yield and purity.     

Die Acylierung von 5-Amino-1 H-1, 2, 4-triazolen. Eine 13C-NMR.-Studie

The Acylation of 5-Amino-1 H-1,2,4-triazoles. A ¹³C-NMR. Study The acylation of 3-substituted-5-amino-1 H-1,2,4-triazoles (1) with methyl chloroformate or dimethylcarbamoyl chloride yielded mainly 1-acyl-5-amino-1,2,4-triazoles ( 2 and 3 ). Acylation of 3-methyl-, 3-methoxy- and 3-methylthio-5-amino-1 H-1,2,4-triazole ( 1b , 1c and 1d ) with methyl chloroformate gave up to 10% of the 1-acyl-3-amino-1,2,4-triazoles. For the unsubstituted 5-amino-1,2,4-triazole (1a) , a (1:1)-mixture of the 3- and 5-isomers 2a and 4 was obtained in dioxane in the presence of triethylamine. No 4-acylated product was detected in contrast to earlier reports. The structures of the reaction products were determined with the aid of proton coupled ¹³C-NMR. spectra using the corresponding N-methyl-1,2,4-triazoles as reference compounds.     

Synthesis of 3-functionalized 3-methylazetidines

1-t-Butyl- and 1-(4-methylbenzyl)-3-bromo-3-methylazetidines were prepared from the corresponding N-(2,3-dibromo-2-methylpropylidene)alkylamines and their propensity to undergo nucleophilic substitution at the 3-position by different nucleophiles was assessed, providing a convenient access to novel 3-alkoxy-, 3-aryloxy-, 3-hydroxy-, 3-cyano-, 3-carboxy-, 3-(aminomethyl)- and 3-(hydroxymethyl)azetidines.     

Quinoline-pyrimidine hybrid compounds from 3-acetyl-4-hydroxy-1-methylquinolin-2(1H)-one: Study on synthesis,cytotoxicity, ADMET and molecular docking

Some novel 2-amino-6-aryl-4-(4′-hydroxy-N-methylquinolin-2′-on-3′-yl)pyrimidines have been synthesized from α,β-unsaturated ketones of 3-acetyl-4-hydroxy-N-methylquinolin-2-one by reaction of corresponding α,β-unsaturated ketones with guanidine hydrochloride. The purity and structure of the obtained products have been confirmed by thin layer chromatography, IR, ¹H NMR, ¹³C NMR, HSQC, HMBC and MS spectra. All the synthesized of 3-(2-amino-6-arylpyrimidin-4-yl)-4-hydroxy-1-methylquinolin-2(1H)-ones 6a-i were screened for their in vitro cytotoxic activity against human hepatocellular carcinoma HepG2 and squamous cell carcinoma KB cancer lines. Compounds 6b and 6e had the best activity in the series, with IC₅₀ values equal to 1.33 μM. Compounds 6a-g exhibited weak or insignificant activity with liver cancer cell lines HepG2, while compounds 6a and 6g had more powerful activity in this sequence, with IC₅₀ values equal to 47.99 and 89.38 μM, respectively. ADMET properties showed that compounds 6b, 6e, and 6f possessed the drug-likeness behavior. Cross-docking results indicated that two hydrogen bonding interactions in the binding pocket, as potential ligand binding hot-spot residues for compounds 6b and 6e, may be one of the mechanisms of action responsible for the higher cytotoxic effect on HepG2 and KB cells.     

An expeditious and efficient synthesis of β-d-galactopyranosyl-(1→3)-d-N-acetylglucosamine (lacto-N-biose) using a glycosynthase from Thermus thermophilus as a catalyst

Mutant glycosynthases or transglycosidases obtained from a Thermus thermophilus β-d-glycosidase (TtbGly) efficiently catalyzed the synthesis of β-(1→3)-disaccharides. Unfortunately, this regioselectivity was changed to the β-(1→4) one when N-acetylglucosamine derivatives were used as acceptors, thus precluding the possibility of synthesizing d-Galp-β-(1→3)-d-GlcpNAc (lacto-N-biose) or d-Glcp-β-(1→3)-d-GlcpNAc, which are useful synthons for the synthesis of antigen determinants. In contrast, we show in this work that, in the presence of phenyl 2-amino-1-thio-β-d-glucopyranoside, the ‘normal’ β-(1→3) regioselectivity of E338G TtbGly glycosynthase takes place. Thus, transglycosylations using α-galactosyl or α-glucosyl fluorides gave the corresponding phenyl β-d-glycopyranosyl-(1→3)-2-amino-2-deoxy-1-thio-β-d-glucopyranosides in high yields (88–97%). Subsequent selective N-acylation followed by NBS/water deprotection of the thiophenyl group afforded lacto-N-biose in high overall yields.     

A concise synthesis of protected diethyl 1-amino-2-hydroxyalkylphosphonates

An efficient diastereoselective synthesis of 5-substituted (2-thioxo-oxazolidin-4-yl)phosphonic acid diethyl esters from metallated diethyl isothiocyanomethylphosphonate and aldehydes has been developed. The three-step transformation of oxazolidine-2-thione derivatives into N-Boc 1-amino-2-hydroxyalkylphosphonic acid diethyl esters is also described.     

Reactions of 2-amino-, 2-alkylamino-, and 2-piperidino-1-azaazulenes with aryl and chlorosulfonyl isocyanates

Reaction of 2-amino-1-azaazulene with phenyl isocyanate gave 3-phenyl-2H-3,4-dihydro-1,3,4a-triazabenz[5,4-a]azulene-2,4-dione. Reactions of 2-alkylamino-1-azaazulenes with aryl isocyanates gave 2-(N-ethyl-N′-arylureido)-1-azaazulenes initially, which rearranged to N-aryl-2-alkylamino-1-azaazulene-3-carboxamides and successive reaction with another molar amount of aryl isocyanate furnished uracil-fuzed 1-azaazulenes. Reaction of 2-piperidino-1-azaazulene with aryl isocyanate gave N-aryl-2-piperidino-1-azaazulene-3-carboxamide. Reaction of 2-(substituted amino)-1-azaazulenes with chlorosulfonyl isocyanate gave 3-cyano- and 3-chloro-2-(substituted amino)-1-azaazulenes.     

A simple and convenient synthesis of substituted furans and pyrroles by CuCl2-catalyzed heterocyclodehydration of 3-yne-1,2-diols and N-Boc- or N-tosyl-1-amino-3-yn-2-ols

A simple and economical synthesis of substituted furans and pyrroles, by ligand-free CuCl₂-catalyzed heterocyclodehydration of readily available 3-yne-1,2-diols and N-Boc- or N-tosyl-1-amino-3-yn-2-ols, respectively, is presented. Reactions are carried out in MeOH at 80-100 °C for 1-24 h and afford the corresponding heterocyclic derivatives in 53-99% isolated yields.