Synthesis of cis- and trans-(±)-3-mercaptoproline and pipecolic acid derivatives via thio-Michael addition

The reactivity of 2,3-dehydroproline and 2,3-dehydropipecolic acid methyl ester derivatives with S-nucleophiles in the thio-Michael addition reaction has been explored. The addition of triphenylmethanethiol and subsequent trityl cleavage led to the corresponding cis- and trans-(±)-3-mercaptoproline and pipecolic acid derivatives in good yields.     

Indole derivatives. 138. Synthesis of α-(5-indolyl)ethylamine and 5-(2-aminoethoxy)- and 5-(aminoethylthio)tryptamines

The reaction of 5-acetylindole with hydroxylamine with subsequent reduction of the resulting oxime gave -(5-indolyl)ethylamine. Coupling of 4-(2-phthalimidoethoxy)- and 4-(2-phthalimidoethylthio)phenyldiazonium chlorides with ethyl -acetyl--phthalimidovalerate, subsequent cyclization of the resulting hydrazones, hydrolysis, decarboxylation, and removal of the phthalyl protecting group led to the formation of 5-(2-aminoethoxy)- and 5-(2-aminoethylthio)tryptamines, respectively.For Communication 137, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 46–48, January, 1992.     

Two-fragment α-adrenolytics. 4. Synthesis of phosphorylated derivatives of 2-aryloxyethylamines and N-phenylpiperazine

The reactions of 3-chloropropylphosphonates, 3-chloropropylthiophosphonates, or 3-chloropropylphosphinates with 2-aryloxyethylamines or N-phenylpiperazine afford the corresponding 3-(2-aryloxyethylamino)propylphosphonates and -phosphinates or 3-(4-phenylpiperazin-1-yl)propylphosphonates and -phosphinates. The compounds obtained exhibit -adrenolytic and hypotensive activities, the latter being found to depend on the substituents at the P atom.     

Reaction of a chlorovinylcarbene with ketenealkyl silyl acetals. Synthesis of new α- and β-allenic carboxylates.

The reaction of ketenealkylsilylacetals with 1,1-dimethyl-2,2,3-trichlorocyclopropane in the presence of methyllithium leads to cyclopropane compounds, which, when treated with tetrabutylammonium fluoride give α- or β-allenic carboxylates.     

Synthesis of new derivatives of α-mangostin (microreview)

Chemistry of Heterocyclic Compounds - This microreview presents the current state of research on functionalization of α-mangostin, a natural hydroxyxanthone. Examples of transformations are...     

Synthesis of 3,3-disubstituted α-tetralones by rhodium-catalysed reaction of 1-(2-haloaryl)cyclobutanols

The rhodium-catalysed reaction of 1-(2-haloaryl)cyclobutanols afforded 3,3-disubstituted α-tetralones. The reaction was applied to the asymmetric synthesis of α-tetralones bearing a chiral quaternary carbon centre at the 3-position, which was otherwise difficult to execute.     

Synthesis with organoboranes. 21. Synthesis of α- and gd-bamascone

Selective syntheses of α- and gd-damascone, using allylic organoboranes as the key intermediates, are described.     

Synthesis of enantiopure norbornane derivatives. Effect of bridgehead substituent on the π-facial selectivity of the reduction of 2-norbornanones and their oximes

One of the most important features of the synthesis of camphor-derived compounds is the control of the stereochemistry at the C2 position. According to this, reduction of bridgehead-substituted 2-norbornanones 1 and 2-norbornanoximes 3 has been considered by us as a very convenient method for the preparation of different classes of enantiomerically pure 1,2- and 1,3-difunctionalised norbornane derivatives. Factors controlling the stereoselectivity in these reductions, as well as the role played by the nature of the bridgehead functional groups are discussed.     

Free-radical intermediates in the electrochemical reduction of α,β derivatives of β-(5-nitro-2-furyl)-α-cyanoethylene

It was found by cyclic voltammetry and ESR that the excitation of the molecules of , derivatives of -(5-nitro-2-furyl)--cyanoethylene in the radical-anion state by one-electron electrochemical reduction promotes chemical transformation of the other reaction centers, while preserving the nitrofuran group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1636–1639, December, 1991.     

Synthesis of 2-aryl-2H-[1,2,4]triazoloquinolin-3-one and 2-aryl-2H-[1,2,4]triazoloisoquinolin-3-one derivatives from α-chloroformylarylhydrazines hydrochloride

The reaction of α-chloroformylarylhydrazines hydrochloride with quinoline under air provided the corresponding 2-aryl-2H-[1,2,4]triazoloquinolin-3-ones 3a-3d in 33-42% yields and unexpected isomeric 2-aryl-2H-[1,2,4]triazoloisoquinolin-3-ones 4a-4d in 30-42% yields. These two isomers were isolated and fully characterized by spectroscopic methods including X-ray crystallography. By employing 3-methylquinoline as the starting material under the same condition, the reaction only gave compound 3e-3h as sole products in 70-82% yields without the formation of isomers. A plausible mechanism was proposed through electrophilic aromatic reaction, the tandem ring cyclization and ring-opening, and oxidation for the generation of 2-aryl-2H-[1,2,4]triazoloisoquinolin-3-ones (4).     

Synthesis and reduction of 9-(α-nitrophenacylidene)-4-azafluorene

Reaction of 9-phenacylidene-4-azafluorene with acetyl nitrate produces a mixture of geometric isomers of 9-(-nitrophenacylidene)-4-azafluorene. The nitro group splits off upon reduction of the product in the system zinc-ammonia and zinc-acetic acid and on Raney nickel. Proceeding of the Henry retro-reaction has been pointed out.Russian Peoples' Friendship University, Moscow 117918, RussiaTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 342–347, March, 1999.     

Generation and cyclization of α-diazocarbothioimidates. Synthesis and structure of derivatives of 5-mercapto-1,2,3-triazole

The reaction of 5-amino-1,2,3-thiadiazol-4-carbothioamides with methyl iodide basically generates -diazo-S-methylthioimidates and -carbothioimidolates. It is shown that the reactivity of the latter increases when either alkyl or aryl substituents are introduced at the nitrogen atom of the carbothioamide groupTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 979–984, July, 1992.     

Derivatives of heterocyclic α-iminocarboxylic acids 3. Synthesis of N-alkoxycarbonyl and N-alkoxycarbonylalkenyl derivatives of α-iminocarboxylic acids

By the interaction of L-proline, L-thioproline, pipecolic acid, tetrahydro-1,4-thiazine-3-carboxylic acid, and diastereomeric esters of tetrahydro-1,4-thiazine-3,5-dicarboxylic acid with methyl chloroformate, methyl propiolate, and acetylenecarboxylic acid, we have obtained N-alkoxycarbonyl and N-alkoxycarbonylalkenyl derivatives of -iminocarboxylic acids. By the reaction of N-methoxycarbonyltetrahydro-1,4-thiazine-3-carboxylic acid with hydrazine hydrate, we have obtained 8-amino-7,9-dioxo-4-thia-1,8-diazabicyclo[4.3.0]nonane.For communication 2, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1561–1566, November, 1993.     

Synthesis and properties of C(9) and C(11) ethyl derivatives of 8-aza-D-homogonanes. The steric factor in the annelation of cyclic Schiff bases by β-triketones

We have studied the steric factors due to the substituents at C₍₁₎ of 3,4-dihydroisoquinolines and in the acyl segment of 2-acyl-1,3-cyclohexanediones that affect the annelation of cyclic Schiff bases by -triketones. Ethyl substituents at C₍₁₎ of 3,4-dihydroisoquinolines show about twice as much retarding effect on reaction rate and yield of desired products as does the replacement of acetyl by butanoyl in 2-acyl-1,3-cyclohexanediones. Derivatives that are ethylated at C₍₁₁₎ of aza-D-homogona-1,3,5(10),13-tetraen-12,17a-diones exist as a mixture of conformers hindered at the C ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1239–1245, September, 1993.     

Highly polarized enamines. 2. Synthesis and investigation of the further amination of derivatives of α,α-DIAMINO-β-cyano-β-nitroethylene

Highly polarized enediamines of the a, -diamino--cyano--nitroethylene type have been obtained by the hydrolysis of 4-chloro-5-nitropyrimidines. Several chemical conversions of the enamines obtained have been studied, particularly leading to derivatives of 2-(cyanonitromethylene)imidazoline and -hexahydropyrimidine, and also to derivatives of N, N-bisvinylpiperazine and 7 methylene-1, 4-diazabicyclo(2.2. 1 ]heptane.Center for Drug Chemistry, All-Russian Chemical and Pharmaceutical Research Institute, Moscow 119815. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 811–820, June, 1996. Original article submitted February 6, 1996.For Part 1, see [1].     

Synthesis,crystal structure and properties of manganese(II) complexes with the tripod ligand tris(2-benzimidazylmethyl)amine and α,β-unsaturated carboxylates

Two new ternary complexes of manganese(II) with tris(2-benzimidazylmethyl)amine (ntb), and two different α,β-unsaturated carboxylates, {[Mn(ntb)(acrylate)](ClO₄)}₂?·?(H₂O)·3(CH₃OH) (1) and {[Mn(ntb)(α-methacrylate)](ClO₄)}₂·(H₂O)·2(CH₃OH) (2), have been synthesized and characterized by means of elemental analyses, thermal analyses, IR, UV and single crystal X-ray diffraction. In the two complexes, ntb functions as a tripodal tetradentate ligand, resulting in trigonal pyramidal geometry. In each complex, an additional ligand, acrylate anion, or α-methacrylate anion, is coordinated at the opened site trans to the apical nitrogen atom of the ntb ligand. The crystal structure of 1 shows two crystallographically independent but chemically identical [Mn(ntb)(acrylate)]⁺ cations. In 2, the crystal structure shows two crystallographically independent and chemically different [Mn(ntb)(a-methacrylate)]⁺ cations. Cyclic voltammograms of the manganese complexes indicate a quasireversible Mn³⁺/Mn²⁺ couple. The X-band EPR spectrum of the complexes exhibits a six-line manganese hyperfine pattern with g?=?2, A?=?97 (1) and 93?G (2). The spectrum confirms that the material is high-spin Mn(II).     

Synthesis,crystal structure and characterization of zinc(II) complexes with the tripod ligand tris(2-benzimidazolylmethyl)amine and α,β-unsaturated carboxylates

Four 5-coordinate zinc complexes containing the tripod ligand, tris(2-benzimidazolylmethyl)amine (ntb), and four different ,-unsaturated carboxylates (L^1–4), with compositions [Zn(ntb)(L^1–4)](NO₃)·nH₂O (L¹ = acrylate; L² = -methacrylate; L³ = trans-cinnamate; L⁴ = 2-hydroxycinnamate; n = 1, 1.5 and 2), were synthesized and characterized by means of elemental analyses, electrical conductivities, thermal analyses, i.r., u.v., and ¹H-n.m.r. spectra. The novel crystal structure of [Zn(ntb)(L³)](NO₃)·H₂O·DMF has been determined by a single-crystal X-ray diffraction method, and shows that each zinc ion is linked to a tris(2-benzimidazolymethyl)amine (ntb) unit and a trans-cinnamate. The zinc ion is 5-coordinate with a N₄O ligand set. The coordination geometries of the zinc ion may be best described as a distorted trigonal bipyramid of site symmetry C₃.     

Synthesis of О-2-(acyl)vinylketoximes and their unusual rearrangements into 2- and 3-acyl-substituted pyrroles

О-2-(Acyl)vinylketoximes (freshly prepared from ketoximes and acylacetylenes in the presence of Ph₃P as catalyst in up to 83% yields) rearrange upon heating (125-150 °C) to give 2- or 3-acylpyrroles, wherein the positions of the acyl substituents do not correspond to known O-vinyloxime rearrangements; the chemo- and regioselectivity of the rearrangements depend on the reaction conditions. The described rearrangement enables syntheses of previously inaccessible substituted 2- or 3-acylpyrroles.     

Synthesis of optically active α-(allenyl)- and α-substituted-α-(allenyl)glycines

The synthesis of various types of optically active α-(allenylsilane-containing)glycines via a chirality-transferring ester-enolate Claisen rearrangement of α-acyloxy-α-alkynylsilanes is described. The conversion of the rearranged products into the optically active silicon-free α-(allenyl)- and α-substituted-α-(allenyl)glycines was achieved by the removal of the Me₂PhSi- or TMS group from the allene terminus.