Synthesis and ozonization of (+)-4α-(1-trimethylsilyloxyethen-1-yl)-2-carene

(+)-4-(1-Trimethylsilyloxyethen-1-yl)-2-carene was synthesized, and the products of its ozonization were identified.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1984–1987, October, 1995.     

Acyl and α-Ketoacyl Complexes of Pt(II) with Weak Donor Ligands

Treatment of trans-Pt(COCOPh)(Cl)(PPh₃)₂ (1a) with AgBF₄in THF led to the formation of a metastatic complex trans-[Pt(COCOPh)(THF)(PPh₃)₂](BF₄) (2) which readily underwent ligand substitution to give a cationic aqua complex trans-[Pt(COCOPh)(OH₂)(PPh₃)₂](BF₄) (5a). Complex 5a has been characterized spectroscopically and crystallographically. Analogous reaction of trans-Pt(COCOOMe)(Cl)(PPh₃)₂ (1b) with Ag(CF₃SO₃) in dried CH₂C1₂ was found first to yield a methoxyoxalyl triflato complextrans-Pt(COCOOMe)(OTf)(PPh₃)₂ (6). Attempts to crystallize the triflato product in CH₂-cl₂hexane under ambient conditions also afforded an aqua complex of the triflate salt f/wu-[Pt(COCOOMe)(OH₂)(PPhj)₂](CF₃SO₃) (5b). Complex 5a in a noncoordinating solvent such as CH₂C1₂ or CHCl₃ suffered spontaneous decarbonylation to form first cis-[Pt(COPh)(CO)(PPh₃)₂l(BF₄) (3a) then the thermodynamically stable isomer trans-[Pt(COPh)(CO)(PPh₃)₂](BF₄) (3b). Crystallization of complex 3b under ambient conditions resulted in an aqua benzoyl complex trans-[Pt(COPh)(OH₂)(PPh₃)₂](BF₄) (7). The replacement of the H_2O ligand in complex 7 by CO was done simply by bubbling CO into the solution of 7. The single crystal structures of 5b and 7 have been determined by X-ray diffraction. The distances of the Pt-O bonds in 5a, 5b, and 7 support that the aqua ligand is a weak donor in such cationic aquaorganoplatinum(lI) complexes, in agreement with their lability to the substitution reactions.     

Ab initio studies on several species of the formula X3YO and X3YOH

Ab initio molecular orbital calculations using both minimal and extended basis sets have been applied to two isoelectronic sets of molecules. One set corresponds to the 18 electron species H₃NO, H₃CO^– and H₃COH while the second set contains the 42 electron fluorinated molecules F₃NO, F₃CO^– and F₃COH. The geometries of these molecules have been optimized, using both the minimal STO-3G and the extended 4-31G basis sets. These comparative calculations reveal that the 4-31G basis produced structural parameters in much better agreement with experiment. The effect of includingd-orbitals in the basis set was also investigated. For the fluorinated oxides it has been found that the optimized 4-31G structures were only slightly altered by the addition ofd-orbitals. For H₃NO, on the other hand, the inclusion ofd-orbitals considerably shortens the N-O bond distance. Both H₃NO and CF₃OH, which are unknown experimentally, are theoretically predicted to be capable of existence. The electronic structures of these molecules have also been examined using electronic partitioning according to the Mulliken scheme.     

The Constituents of the Leaves of Chamaecyparis Formosensis Matsum

Forty one terpenoidal compounds were isolated from the essential oil of Chamaecyparis formosensis Matsum. The dominant component is α-pinene. Other major components include β-pinene, 3-carene, α-terpineol, γ-muurolene, and kaurene.     

Manganese(III) acetate mediated synthesis of 3-trifluoroacetyl-4,5-dihydrofurans and 3-(dihydrofuran-2(3H)-ylidene)-1,1,1-trifluoroacetones by free radical cyclization. Part 1

2-Trifluoroacetyl-4,5-dihydrofurans were obtained by manganese(III) acetate mediated radical cyclization of trifluoromethyl-1,3-dicarbonyl compounds (1a-c) with conjugated alkenes (2a-h). The reaction of 1,1,1-trifluoropentane-2,4-dione (1a) with propenylbenzene and 1,1-diphenyl-1-butene surprisingly yielded 3-(dihydrofuran-2(3H)-ylidene)-1,1,1-trifluoroacetones besides 3-trifluoroacetyl-4,5-dihydrofurans.     

New insight into the oxidative chemistry of noradrenaline: competitive o-quinone cyclisation and chain fission routes leading to an unusual 4-[bis-(1H-5,6-dihydroxyindol-2-yl)methyl]-1,2-dihydroxybenzene derivative

Oxidation of 5×10⁻³ M noradrenaline in aqueous phosphate buffer, pH 7.4, with K₃Fe(CN)₆, NaIO₄ or Fe²⁺/EDTA/H₂O₂ followed by extraction with ethyl acetate and acetylation with Ac₂O/Pyr led to a main reaction product which was isolated and identified as 4-[bis-(1H-5,6-diacetoxyindol-2-yl)methyl]-1,2-diacetoxybenzene, an unprecedented [bis-(indol-2-yl)methyl]-benzene derivative unsubstituted on the 3-position of the indole rings. This product was also obtained in 40% yield by reaction of 5,6-dihydroxyindole with 3,4-dihydroxybenzaldehyde. Other components of the oxidation mixture were 1-acetyl-3,5,6-triacetoxyindole, derived from noradrenolutin, and 5,6-diacetoxyindole, originating from cyclisation/dehydration of the o-quinone of noradrenaline, along with some 3,4-diacetoxybenzaldehyde. Inspection of the aqueous phase revealed the presence of 3,4-dihydroxymandelic acid and 3,4-dihydroxybenzaldehyde, derived from oxidative breakdown of the 2-amino-1-hydroxyethyl chain via a p-quinomethane intermediate. These results disclose new aspects of the oxidative chemistry of noradrenaline beyond the aminochrome stage and provide a route to novel [bis-(indol-2-yl)methyl]-benzene derivatives of potential pharmacological interest.     

Synthesis of bridgedhead azolo[3,2-a]pyrimidines and imidazo[2,1-b]thiazines through ring transformation of 2H-pyran-2-ones

Suitably functionalized 3-carbomethoxy/cyano-2H-pyran-2-ones are excellent synthons for the synthesis of arenes and heteroarenes of therapeutic importance. The compounds 6-aryl-3-cyano-4-methylsulfanyl-2H-pyran-2-ones have been transformed into bridgedhead azolopyrimidines and imidazothiazines through thermal and base-induced ring transformation reactions with aminoazoles and imidazolidin-2-thiones, respectively.     

Complexes of heteroscorpionate trispyrazolylborate ligands. Part VI. Carboxylate induced conversion of mono-ligand Tp′M(L) into bis-ligand Tp′2M complexes (M=Co(II) and Cu(II))

A series of homoleptic complexes of hexacoordinate cobalt(II) and copper(II) complexes with 3,5-disubstituted homo- and heteroscorpionate tris(pyrazolyl)borate anionic ligands (Tp′) were synthesized, i.e. bis[hydrotris(3-phenyl,5-methylpyrazol-1-yl)borato]cobalt(II), bis[hydrobis(3-phenyl,5-methylpyrazol-1-yl)(3-methyl,5-phenylpyrazol-1-yl)borato]cobalt(II) and bis[hydrobis(3-phenyl,5-methylpyrazol-1-yl)(3-methyl,5-phenylpyrazol-1-yl)borato]copper(II) and their structures were elucidated crystallographically. The complexes were also formed spontaneously during attempted metathesis of the corresponding Tp′M(NCS) complexes into Tp′M(OOCCH(OH)CH₃) complexes. In the case of the analogous conversion applied for the thiocyanato [hydrobis(3-phenyl,5-methylpyrazol-1-yl)(3,5-dimethylpyrazol-1-yl)boratocobalt(II) complex with sodium carboxylates (lactate, pyruvate and 2-hydroxybutyrate), the cross-transfer of pyrazolyl residues between starting anionic ligands was observed resulting in formation of bis-ligand homo- and heteroleptic Tp′CoTp″ complexes, where Tp′, Tp″ were tris(pyrazolyl)borates composed of n 3(5)-phenyl,5(3)-methylpyrazolyl and (3−n) 3,5-dimethylpyrazolyl residues (n=0–3) identified by mass spectrometry. Metathesis of thiocyanate in thiocyanato hydrotris(3-phenyl,5-methylpyrazol-1-yl)boratocobalt(II) into pyruvate led to the isolation of stable the pyruvato hydrotris(3-phenyl,5-methylpyrazol-1-yl)boratocobalt(II) complex, the structure of which was determined crystallographically. The Tp′ ligands are η³ coordinated to metal ions in every case, whereas the pyruvate anion is coordinated through carboxylate and carbonyl oxygen atoms to the cobalt center. Two rotational isomers distinguishable by ¹H NMR spectroscopy for the hexacoordinate bis[hydrobis(3-phenyl,5-methylpyrazol-1-yl)(3-methyl,5-phenylpyrazol-1-yl)borato]cobalt(II) complex were detected in solution.     

Synthesis and thermal transformations of polyphosphosiloxane based on trimethyl phosphate and (3-aminopropyl)triethoxysilane

A method for the synthesis of polyphosphosiloxane by the thermal condensation of an equimolar mixture of trimethyl phosphate and (3-aminopropyl)triethoxysilane at 200 °C was developed. The reaction affords ethanol and polyphosphosiloxane-{Si(OEt)[(CH₂)₃NR¹R²]-O-P(O)(OMe)-O}_n-(R¹ = H, Me; R² = Me), whose composition and structure were confirmed by ¹H, ¹³C, and ³¹P NMR spectroscopy, IR spectroscopy, and elemental analysis. The scheme of polymerization involving the intermediate formation of methyl-and dimethylphosphoric acids and their condensation with ethoxysilanes was proposed. The calcination of the obtained polyphosphosiloxane in vacuo at 350 °C results in the elimination of the amino groups and alkoxide substituents, and a spatially cross-linked polymer is formed as an amorphous powder. Its further thermolysis at 600 and 1000 °C gives crystalline phosphosilicates Si₅O(PO₄)₆ or SiP₂O₇. Their amorphous and crystalline samples were characterized by IR spectroscopy, X-ray diffraction analysis, and solid-state ¹³C and ³¹P spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2138–2148, November, 2007.     

Study on the hydrogen donating abilities of benzofuranones as chain-breaking antioxidants using laser flash photolysis technique

The hydrogen donation kinetics of four 3-aryl-benzofuranones with different chemical structures toward tert-butoxyl radicals were studied using laser flash photolysis (LFP) technique. The rate constants of hydrogen reactions, which can be used to evaluate the hydrogen donating abilities of 3-aryl-benzofuranones toward radicals, were obtained. The results showed that the position of substituted methyl group has a very important effect on the hydrogen donating ability of benzofuranone toward tert-butoxyl radicals, i.e. if the methyl group is on 2′-position, the hydrogen donation of 3-aryl-benzofuranone toward tert-butoxyl radicals will be prevented and the hydrogen donating ability will be weakened.