A new synthesis of spiro-fused 1,4-benzothiazines

A new preparative procedure was developed for the synthesis of spiro-fused 1,4-benzothiazines by thermal heterocyclization of S-benzyl and S-phenacyl derivatives of o-indothiophenol.     

Cyclocondensation of ethyl 3,3-diaminoacrylate with aromatic ketones and nitriles containing a labile halogen atom in the <Emphasis Type="Italic">ortho</Emphasis> position

The cyclocondensation of aromatic o-halo ketones and o-halo nitriles with ethyl 3,3-diaminoacrylate proceeds as the replacement of the aromatic halogen by the α-carbon atom of the enediamine, while the amino group of the enediamine is bound by the α-carbon atom of the ketone or nitrile group. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 585–588, April, 2008.     

New lead(II) catecholate and o-semiquinone complexes

Lead(II) catecholate complexes were prepared by reduction of 3,6-di-tert-butyl-o-benzoquinone and its derivatives with lead metal in THF. The molecular structure of the (CatPb)₄·(PbO)₂·6C₃H₆O complex (Cat is the dianion of 3,6-di-tert-butylcatechol), which was synthesized by hydrolysis of lead 3,6-di-tert-butylcatecholate in acetone, was established by X-ray diffraction. A series of lead(II) o-semiquinone complexes, which were prepared by the addition of the phenoxyl radical to lead catecholates or by oxidation of the latter with mercury(II), copper(II), or silver(I) halides, were studied by the ESR method. Lead(II) mono-o-semiquinolate complexes undergo symmetrization to form stable bis-o-semiquinolates, which were isolated and characterized in individual state. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1103–1111, July, 2006.     

Synthesis of magnesium catecholate and <Emphasis Type="Italic">o</Emphasis>-semiquinone complexes by oxidation of the metal with 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-<Emphasis Type="Italic">o</Emphasis>-benzoquinone

Oxidation of amalgamated magnesium metal with 3,6-di-tert-butyl-o-benzoquinone (1) in different aprotic organic solvents afforded magnesium catecholate and bis-o-semiquinolate complexes. The catecholate derivatives of magnesium CatMgL₂ (Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion, L = THF or Py) were synthesized in high yields in pyridine and tetrahydrofuran, respectively. The reactions in diethyl ether or dimethoxyethane produced hexacoordinated metal bis-o-semiquinolates SQ₂MgL_n (SQ is the 3,6-di-tert-butyl-o-benzoquinone radical anion, L = Et₂O, n = 2; L = DME, n = 1). The reaction with the use of toluene as the solvent gave a magnesium bis-o-semiquinolate complex containing the coordinated unreduced o-quinone molecule. The molecular structures of the [CatMgPy₂]₂ and SQ₂Mg·DME complexes were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–98, January, 2007.     

Novel Syntheses of 2,3-Disubstituted Benzothiophenes

The sodium salts of o-sulfanylphenyl ketones 3a-g were treated with -benzotriazol-1-ylalkyl chlorides 4a,b to give intermediates 5a-k in good yields. Compounds 5a-k, on treatment successively with LDA and Ti (0), gave benzothiophenes 7a-k.     

A reaction of 3,6-di(tert-butyl)-4-chloro-1,2-benzoquinone with potassium ethyl xanthate. New sulfur-containing o-quinones

In a reaction of 3,6-di(tert-butyl)-4-chloro-1,2-benzoquinone with potassium ethyl xanthate, the halogen atom was replaced by the ethyl xanthate group. Acid hydrolysis of the product gave 4,7-di(tert-butyl)-5,6-dihydroxy-1,3-benzodithiol-2-one containing a pyrocatechol fragment, which was oxidized into the corresponding quinone. When irradiated in solution with visible light, this quinone quantitatively eliminated a CO molecule with contraction of the ring to a five-membered one. The quinones obtained were studied as ligands in coordination spheres of metals by ESR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 683–686, April, 2006.     

Heterocyclization of o-(arylethynyl)arylhydrazines as a new procedure for the synthesis of substituted 1H- and 2H-indazoles and indoles

Procedures for the preparation of 3-substituted 1H- and 2H-indazoles and 2-substituted indoles were developed based on cross-coupling of o-iodoarylhydrazines with copper acetylenides in pyridine or dimethylformamide. An alternative procedure for the synthesis of 3-substituted 1H-indazoles involves cyclocondensation of (2-chloroaryl)acetylenes with hydrazine hydrate in butanol.     

Quinonimines and aminoquinones, the reaction products of 3,6-di(tert-butyl)-o-benzoquinone with primary and secondary amines

Reactions of 3,6-di(tert-butyl)-o-benzoquinone with primary amines occur by the nucleophilic 1,4-addition mechanism and lead to the corresponding 2-hydroxy-p-quinonimines, which exist in solutions in equilibrium with tautomeric 4-amino-o-quinones. The thermodynamic parameters of this prototropic isomerism were determined by NMR spectroscopy. In the case of a secondary amine (piperidine), a derivative of 4-amino-o-quinone was obtained; the corresponding o-semiquinone complexes were studied in solution by ESR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1151–1155, July, 2006.     

Synthesis and structures of five-coordinate bis-o-iminobenzosemiquinone complexes M(ISQ-R)2X (X = Cl, Br, I, or SCN; M = CoIII, FeIII, or MnIII)

New five-coordinate complexes Co(ISQ-Prⁱ)₂Cl, Co(ISQ-Me)₂Cl, Co(ISQ-Me)₂I, Co(ISQ-Me)₂(SCN), Mn(ISQ-Prⁱ)₂Cl, and Fe(ISQ-Me)₂Br (ISQ-Prⁱ and ISQ-Me are the 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-and 4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-o-iminobenzosemiquinone radical anions, respectively) were synthesized. The complexes were characterized by UV-Vis and IR spectroscopy and magnetochemistry. The molecular structures of the Fe(ISQ-Me)₂Br and Mn(ISQ-Prⁱ)₂Cl complexes were established by X-ray diffraction. The singlet ground state (S = 0) of the cobalt complexes is caused by antiferromagnetic coupling between the unpaired electrons of the radical ligands (S = 1/2) through the fully occupied atomic orbitals of low-spin cobalt(III) (d⁶, S = 0). The effective magnetic moments of the complexes at 10 K are 0.18 μ_B for Co(ISQ-Prⁱ)₂Cl and 0.16 μ_B for Co(ISQ-Me)₂I. The ground state of the manganese complex is triplet (S = 1). Two unpaired electrons of the o-iminobenzosemiquinone ligands are strongly antiferromagnetically coupled with two of four unpaired electrons of high-spin manganese(III) (d⁴, S = 2). Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 43–51, January, 2006.     

三邻氯苄基和三邻氟苄基锡吡咯烷氨荒酸酯的合成及晶体结构

Tri(o-chlorbenzyl)tin dithiotetrahydropyrrolocarbamate 1 and tri(o-fluorbenzyl)tin dithiotetrahydropyrrolocar-bamate 2 were synthesized. Their structures were characterized by elementary analysis， IR and ¹H NMR and the crystal structures were determined by X-ray single crystal diffraction. The crystal 1 belongs to triclinic with space group ， a=0.9076(4)nm， b=1.0663(5)nm， c=1.5193(7)nm， α=75.811(6)°，β=89.344(6)°， γ=72.665(6)°， Z=2， V=1.3577(11)nm³， D_c=1.569g·cm^-3， μ=1.406mm^-1， F(000)=644， R=0.0282， wR=0.0617. The crystal 2 belongs to monoclinic with space group P2₁/c， a=1.355(2)nm， b=1.0143(16)nm， c=1.986(3)nm， β=109.94(2)°， Z=4， V=2.565(7)nm³， D_c=1.539g·cm^-3， μ=1.195mm^-1，F(000)=1200， R=0.0467， wR=0.0788. In the crystals of 1 and 2， the structures consist of discrete molecules containing five-coordinate tin atom in a distorted trigonal bipyramidal configuration. CCDC: 1， 213679; 2， 213680.