Diastereoselective Syntheses of (+)-α-Cyperone and Its C-10 Epimer

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Synthesis and Antitumor Activity of C-2／C-10 Modified Analogues of Docetaxel

Four 10-propionyl docetaxel analogues (lla-d) with 2α-amido substituents were prepared, and their antitumor activity against three solid tumor cell lines and their drug-resistant counterparts were determined.     

An Unusual Formation of Cyclic Sulfite at C-4 and C-5 Positions of Taxane

An unusual formation of cyclic sulfite at C-4 and C-5 positions of taxane was accomplished by treatment of compound 1 with excess MeSOEC1/Et3N and a possible mechanism was proposed.     

Alkylation of C- and N-aminotriazoles with α-iodoketones

C- and N-Amino-1,2,4-triazoles react with 1-iodopropan-2-one in the absence of bases and phasetransfer catalysts (40°C, 9-12 h) to furnish 3-amino-1,4-bis(2-oxo-propyl)-4H-1,2,4-triazolium triiodide and 4-amino-1-(2-oxopropyl)-4H-1,2,4-triazolium iodide. The alkylation of 1,2,4-triazol-4-amine with 1-iodopropan-2-one and 1,3-diiodopropan-2-one in the presence of elemental iodine led to the formation of 4-amino-1-(2-oxopropyl)-4H-1,2,4-triazolium triiodide and 2-oxopropane-1,3-diylbis(4-amino-4H-1,2,4-triazolium) bis(triiodide). Triiodides are oily fluids possessing electric conductivity of 1.1 × 10^?3 Ω m^?1 opening the route to new types of electroconducting ionic liquids.     

α-Aminoxylation of Ketones and β-Chloro-α-aminoxylation of Enones with TEMPO and Chlorocatecholborane

Oxidation of various cyclic and acyclic ketones under mild conditions with chlorocatecholborane, a bulky pyridine base, and TEMPO to the corresponding α-aminoxylated products in good to excellent yields (52-99%) is described. For enones as substrates, products of a β-chloro-α-aminoxylation are obtained (70-89%).     

Competing C-4 and C-5-Acyl Stabilization of Uronic Acid Glycosyl Cations

Uronic acids are carbohydrates carrying a terminal carboxylic acid and have a unique reactivity in stereoselective glycosylation reactions. Herein, the competing intramolecular stabilization of uronic acid cations by the C-5 carboxylic acid or the C-4 acetyl group was studied with infrared ion spectroscopy (IRIS). IRIS reveals that a mixture of bridged ions is formed, in which the mixture is driven towards the C-1,C-5 dioxolanium ion when the C-5,C-2-relationship is cis, and towards the formation of the C-1,C-4 dioxepanium ion when this relation is trans. Isomer-population analysis and interconversion barrier computations show that the two bridged structures are not in dynamic equilibrium and that their ratio parallels the density functional theory computed stability of the structures. These studies reveal how the intrinsic interplay of the different functional groups influences the formation of the different regioisomeric products.     

Aryl-ONN-azoxy-α,α-dinitroalkanes and some of their derivatives

Previously unknownN-dinitroalkyl-NNO-azoxybenzenes have been prepared (by nitration ofN-(-hydroximino) alkyl-NNO-azoxybenzenes) and transformed to some derivatives.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1972–1975, November, 1994     

C- and O-Alkylation with α-Haloketones of the Adamantane Series

Reactions of 1-adamantyl bromomethyl ketone and 1-(1-adamantyl)-3-bromo-2-propanone with acetylacetone and ethyl acetoacetate in a mixture of dry diethyl ether with anhydrous methanol in the presence of sodium methoxide afforded 3-(1-adamantylcarbonylmethyl)-2,4-pentanedione, ethyl 2-(1-adamantylcarbonylmethyl)-3-oxobutanoate, 4-acetyl-1-(1-adamantyl)-2,5-hexanedione, and ethyl 2-acetyl-5-(1-adamantyl)-4-oxopentanoate. The Knoevenagel-Cope reactions of 1-adamantyl bromomethyl ketone and 1-(1-adamantyl)-3-bromo-2-propanone with diethyl malonate yielded, respectively, diethyl 1-(1-adamantyl)-2-bromoethylidenemalonate and diethyl 1-(1-adamantylmethyl)-2-bromoethylidenemalonate. O-Alkylation of ethyl acetoacetate with 1-adamantyl bromomethyl ketone gave ethyl 3-(1-adamantylcarbonylmethoxy)-2-butenoate. Carboxylic acids reacted with 1-adamantyl bromomethyl ketone to form the corresponding 2-(1-adamantyl)-2-oxoethyl carboxylates.     

Synthesis of alkyl-α,α-dimethylcyclopropanemethanols and alkylcyclopropyl methyl ketones

Russian Chemical Bulletin -     

Synthesis and antioxidant activity of phenolic derivatives ofα-santonin

Phenolic derivatives of-santonin have been synthesized and their antioxidant effect has been studied.Institute of Phytochemistry, National Academy of Sciences of the Republic of Kazakhstan, Karaganda. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 247–249, March–April, 1997.     

Synthesis and Crystal Structure of β-Amino-α-Phenyl-α-Ferrocenylethanol

β-Amino-α-phenyl-α-ferrocenylethanol, FcC(OH)(Ph)CH₂NH₂ was prepared by the reduction of cyanohydrin trimethylsilyl ether of benzoylferrocene with lithium aluminum hydride. This new compound was characterized by elemental analysis, IR and ¹H NMR spectroscopy. The structure was also confirmed by a single crystal X-ray study. The compound crystallizes in monoclinic P2₁/c space group with unit cell dimensions: a = 12.5906(17), b = 5.9636(8), c = 19.8320(3) Å, β = 102.047(2)^∘, V = 1456.3(3) ų, Z = 4. The structure exhibits intra- and inter-molecular hydrogen bonding of the type N—H⋅ < eqid1 > ⋅O and O—H⋅ < eqid2 > ⋅N, respectively. The pattern of the inter-molecular hydrogen bonding interaction contains a 10-atom ring with two donors and two acceptors, showing a dimeric crystal packing.     

Synthesis and structure of β-aryl-α-nitroacrylates

The method for preparation of ethyl α-nitrocinnamates by nitroacetic acid ester alkenylation with aromatic aldehydes in the presence of acetic acid and β-alanine has been modified. Structures of the prepared compounds have been proved by electronic, IR, ¹H, and ¹³C-{¹H} NMR spectroscopy (including heteronuclear correlation experiments ¹H-¹³C HMQC and ¹H-¹³C HMBC). In solution these compounds exist in the form of Z-isomer; the Z?E isomerization is observed in the case of the compound containing strong electron-donor group [N(CH₃)₂] at benzene ring.     

α-Thioureidoalkylation of 4-alkyl- and 4-phenylthiosemicarbazides

Previously unknown 1,3-dialkyl-4,5-bis[4-alkyl(phenyl)thiosemicarbazido]imidazolidine-2-thiones and 4,5,7-trialkylperhydroimidazo[4,5-e]-1,2,4-triazine-3,6-dithiones have been synthesized by the α-thio-ureidoalkylation of 4-alkyl(phenyl)thiosemicarbazides using 1,3-dialkyl-4,5-dihydroxyimidazolidine-2-thiones.     

α-Halo Ketones in C-, N-, O-, and S-Alkylation Reactions

The review summarizes and analyzes both theoretical aspects and practical applications of C-, N-, O-, and S-alkylation with -halo ketones of aliphatic, alicyclic, aromatic, and heterocyclic compounds. Some reactions of -halo ketones with difunctional nucleophiles are also discussed.     

Reactivity of C-10 Function in Sinenxan A and Its Derivatives

SinenxanA(1)isabioSynheticallyavailallletaxoidI'1ComParedwiththehaousanticanceragentPaClitaxel(taxol',2)[2],themOStconSPicuouschrencebebenthesetW0co~dsinthelocallonOfOxygnnfunchonsisl4P-0AcinthefOrmerandl3a-0C0Rinthelatter.Wththeaimof~ningnewanhcanceragents,wewereinterestedinInakingchendcalmedCationsonsinenxanAincluding,amongothers,theconSructon0ftheoxetanering'],andtheattaChmentOfanisoserine-twsidechainatl4-positionasadricryOf2.InthecourseOfitSforcturaJm~CatioftweboserVedthaitSC-…     

Kinetic and mechanism of reactions of L-α-Glutamic acid and L-Glutamine with pyridoxal

The kinetics and mechanisms of condensation of pyridoxal with L-α-glutamic acid and L-glutamine were studied by UV spectroscopy and polarimetry. L-α-Glutamic acid reacts with pyridoxal to form a Schiff base whose subsequent hydrolysis gives rise to pyridoxamine and α-ketoglutaric acid. The reaction of Lglutamine with pyridoxal involves the Γ-NH₂ group and affords a Schiff base whose subsequent hydrolysis gives rise to pyridoxamine and L-α-glutamic acid.     

N-Phospho-α-Amino Acids and Co-Evolution of Nucleic Acid and Protein

N-phospho-α -amino acids obtainable from aqueous condition were different from their corresponding β -analogues intrinsically. As the self-reproduction unites, N-phospho-α -amino acids were capable to produce non-random oligopeptides. As the phosphoryl donor, they were able to phosphorylate the nucleosides much faster than the deoxynucleosides.     

Synthesis of New Cα,α-Diarylaminomethylphosphonic Acids and their Esters

Abstract

A procedure for the preparation of N-protected 1 or unprotected C_a,a-disubstituted (diarylaminomethyl)-phosphonic acids and their esters is reported.¹ This method is a generalisation of the Kabachnik-Fields method described in the literature.²