Titanium mediated alkylidenation of substituted cycloalkenones: scope and limitations

The conversion of the cyclopent-2-enone 5 and cyclohex-2-enones 11a, c-e into corresponding α′-exo-alkylidene compounds using Ti(IV) catalysis, with PPh₃ and an aldehyde, is described.     

Reaction of 5-allyl-2,5-dichloro-4,4-dimethoxy-3-morpholinocyclopent-2-enone with Me3SiI

5-Allyl-2,5-dichloro-4,4-dimethoxy-3-morpholinocyclopent-2-enone reacts with Me₃SiI in MeCN to give the corresponding product of reductive vinylic monodechlorination. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1660–1661, August, 1998.     

Toward understanding the scope of Baylis-Hillman reaction: synthesis of 3-(2- hydroxyphenyl)indolin-2-ones and polycyclic fused furans

A facile one-pot synthesis of 3-(2-hydroxyphenyl)indolin-2-ones has been developed via the TiCl₄-mediated Baylis-Hillman (B-H) reaction of N-substituted isatins and cyclohex-2-enone, followed by treatment of the in situ generated B-H alcohols with aq HBr. Baylis-Hillman reaction of aromatic cyclic 1,2-diones with cycloalk-2-enones under the influence of TiCl₄ has been successfully performed and the resulting Baylis-Hillman adducts have been conveniently transformed into pentacyclic and hexacyclic fused furan derivatives.     

Recyclization of 5-allenyl-2,5-dichloro-3-N,N-dimethylamino-4,4-dimethoxycyclopent-2-enone under the action of SmI2−(Me2N)3P. Functionalizedcis-, trans-cycloocta-2,6-dienones

Reaction of 5-allenyl-2,5-dichloro-3-N,N-dimethylamino-4,4-dimethoxycyclopent-2-enone with Sml₂−(Me₂N)₃P affords new functionalizedcis-,trans-cycloocta-2,6-dienones. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2552–2553, December, 1998.     

A convenient synthesis of 2,5-diaroyl-4-hydroxy cyclopent-2-enones incorporating aromatic and heteroaromatic moieties

Abstract

The base-catalyzed reaction of 1,5-diphenyl-pentane-1,3,5-trione with aromatic/heteroaromatic 1,2-diones leading to the synthesis of 2,5-diaroyl-4-hydroxycyclopent-2-enones and its conversion to 2,5-diaroylcyclopentadienones is reported here. 2,5-Dibenzoyl-4-hydroxycyclopent-2-enone and 2,5-dithenoyl-4-hydroxycyclopent-2-enone are valuable compounds which act as chemosensors for selective detection of Fe³⁺ and Cu²⁺, respectively.     

Photochemistry of 6,6-Dimethyl- and 2,2,6,6-Tetramethyl-2H,6H-pyran-3-one

The title compounds 1a and 1b have been synthesized in two steps from the saturated pyran-3-ones 2a and 2b , respectively. Upon irradiation (254 nm or 350 nm) in dilute solutions (10^?3?10^?2M ), compounds 1 undergo a formal [4 + 2] cycloreversion from the excited triplet state to give (2-methylprop-1-enyl)ketene ( 11 ) and either formaldehyde or acetone, ketene 11 being trapped by H₂O or MeOH to afford 4-methylpent-3-enoic acid ( 5 ) or its methyl ester 4 in 75–85% isolated yield. In this (monomolecular) photoreaction, heterocycles 1 differ from their alicyclic counterparts, i.e., 4,4-dimethylcyclohex-2-enone ( 10a ) and 4,4,6,6-tetramethylcyclohex-2-enone ( 10b ), as no rearrangement to a 4-oxabicyclo[3.1.0]hexan-2-one occurs. On the other hand, the photochemical behavior of pyranone 1a in bimolecular reactions (cyclodimerization, [2 + 2] cycloaddition to 2,3-dimethylbut-2-ene) resembles that of enone 10a .     

Regio- and stereochemistry of the photo-ring contraction of 4-pyrones

Irradiation of 2-ethyl-3-methyl-4-pyrone 3 in aqueous solution led to the formation of trans-4-ethyl-5-methy-4,5-dihydroxycyclopent-2-enone 4 and trans-2-methyl-3-ethyl-4,5-dihydroxycyclopent-2-enone 5 . In the latter case ¹H nmr analysis confirmed the trans-configuration at C₄ and C₅ . These results are consistent with trapping of a photochemically generated oxabicyclohexenyl zwitterion by nucleophilic attack of both sides of the oxyally system along a path anti to the epoxide ring.     

Photochemistry of 6-trifluoromethyl-4,4-dimethyl-2-cyclohexenone

The photochemical behaviour of the title compound, newly synthesized in four steps from 4,4-dimethylcyclohexanone, is compared to that of 4,4-dimethyl- and 4,4,6-trimethyl-2-cyclohexenone. All three enones undergo rearrangement to bicyclo[3.1.0]hexan-2-ones and 3-isopropyl-2-cyclopentenones in benzene, t.butanol and acentonitrile, but only the CF₃-enone is also reduced to the saturated ketone in the latter two solvents.     

Synthesis,Characterizations, Magnetism and Thermal Degradation of a 2‐Fold Interpenetrated 3D Cobalt‐Organic Framework

A new coordination polymer, [Co₂(L)₂(4,4′‐bipy)]_n·3nH₂O ( 1 ) based on 5‐(3‐methyl‐5‐phenyl‐4H‐1,2,4‐triazol‐4‐yl)isophthalic acid (H₂ L ) and 4,4′‐bipyridine (4,4′‐bipy) has been hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction, XRPD, IR, and elemental analysis. Temperature‐dependent magnetic susceptibility and thermal degradation for 1 were also studied. The asymmetric unit of compound 1 consists of two crystallographically independent Co(II) ion, two L ^2? ligand, one 4,4′‐bipy ligand, and three lattice water molecules. The 2D triangle networks were linked by the bridging 4,4′‐bipy ligand to give rise to a 2‐fold interpenetrated 3D architecture. The simplest cyclic motif of the 2D networks is a triangle ring consisting of three Co(II) cations and three L ^2? ligands. So we can define Co(II) ions as 4‐connected nodes and the L ^2? ligands as 3‐connected nodes. Thus, the 3D structure can be described as a 2‐fold parallel interpenetrated ins InS 3,4‐conn topology.     

Reaction of η-enone and enal-platinum(0) complexes with Lewis acidic compounds

Reaction of η²-enone and enal-platinum(0) complexes Pt(CH₂CHCOR)(PPh₃)₂ (R=H, Me) with Lewis acidic compounds BX₃ (X=F, C₆F₅) afforded adducts formed by coordination of boron to oxygen of the carbonyl group. The X-ray structure determination of the adduct formed from B(C₆F₅)₃ and η²-methylvinylketone complex showed no strong interaction between Pt and carbonyl carbon. In contrast to the inability of the palladium(0) η²-enone complexes to form any Me₃Al adduct, η²-cyclohexenoneplatinum(0) complex formed an isolable adduct with Me₃Al, the structure of which was also confirmed by X-ray analysis. The NMR spectral parameters (Pt-C, Pt-P and P-P coupling constants) of these adducts were compared with those of the original η²-enone or enal-platinum(0) complexes as well as the ordinary η³-allylplatinum cation [Pt(PPh₃)₂(MeCHCHCH₂)]⁺.     

3-D Coordination polymer containing a 1-D tunnel filled with 4,4′-bpy: synthesis,crystal structure,and characterization

A coordination polymer, [Co(2-mpac)₂(4,4′-bpy)·(4,4′-bpy)] _n (2-mpac: 5-methyl-2-pyrazinecarboxylic acid; 4,4′-bpy: 4,4′-bipyridine), has been synthesized through hydrothermal synthesis and structurally characterized by X-ray single crystal diffraction. Single crystal X-ray diffraction analysis reveals a 3-D network featuring a 1-D tunnel filled with 4,4′-bpy molecules. Elemental analysis, IR, thermogravimetric analysis, and magnetic properties are presented.     

Cyclobut-2-enones from Alkynes via Dichlorocyclobut-2-enones

The [2 + 2]-cycloaddition of dichloroketene (prepared in situ from CCl₃COCl and Zn(Cu)) with three alkynes 1a–c to form 2,3-dimethyl-( 2a ), 2,3-diethyl-( 2b ) and 3-butyl-4,4-dichlorocyclobut-2-enone ( 2c ) proceeds rapidly in the absence of POCl₃. The primary products 2a–c rearrange in situ to the 2,4-dichlorocyclobut-2-enones 3a–c under the influence of ZnCL₂ produced during the reaction. ZnCl₂ converts both 2a and 3a into a 4:6 equilibrium mixture of the two; this isomerization does not occur with LiCl. The Cl-atoms of both 2a , b and 3a , b and of 2c may reductively be removed with Zn(Cu) in AcOH/pyridine to afford the alkylcyclobutenones 4a-c . Without pyridine, this reduction gives ca. 1:1 mixtures of the double-bond isomers 4 and 5 in low yields. The cyclobutenones 2c and 4c may be deuterated by CD₃COOD in the presence of pyridine. D -Atom is introduced into 2c at C(4) and at C(γ), and into 4c at C(2) and C(4). A mechanism for this deuteration is considered, which does not involve a cyclobutadienolate 7 , but rather a cyclobutenolate of type 8 . The reductions of 2 and 3 to 4 might also pass through the same type of intermediate 8 .     

两种3D微孔Zn-MOF对水溶液中Fe3+、Cr2O72-和丙酮分子的荧光传感(英文)

通过溶剂热法合成了2种三维微孔锌金属有机框架材料,其分子式为[Zn₃(DBA)(OH)(1,10-phen)₂]_n (1)和{[Zn₂(HDBA)(4,4′-bipy)_1.5]·H₂O}_n (2)(H₅DBA=3,5-二(2′,4′-对羧基苯基)苯甲酸;1,10-phen=1,10-菲咯啉;4,4′-bipy=4,4′-联吡啶)。结构分析表明,配合物1为三核锌基金属单元的三维微孔骨架,配合物2为双核锌基的微孔结构。与2相比,配合物1在水中具有较强的发光性能,可作为检测Fe³⁺、Cr₂O₇^2-和丙酮分子的发光传感器,具有较高的选择性和灵敏度。     

Efficient Synthesis of Novel Coumarin‐3‐carboxamides (=2‐Oxo‐2H‐1‐benzopyran‐3‐carboxamides) Containing Lipophilic Spacers

The novel coumarin‐3‐carboxamides (=2‐oxo‐2H‐1‐benzopyran‐3‐carboxamides) 5a – 5g containing lipophilic spacers were synthesized through the Ugi‐four‐component reaction (Scheme 1). The reactions of aromatic aldehydes 1 , 4,4′‐oxybis[benzenamine] or 4,4′‐methylenebis[benzenamine] as diamine 2 , coumarin‐3‐carboxylic acid (=2‐oxo‐2H‐benzopyran‐3‐carboxylic acid; 3 ), and alkyl isocyanides 4 lead to the desired substituted coumarin‐3‐carboxamides 5a – 5g at room temperature with high bond‐forming efficiency. These novel coumarin derivatives exhibit brilliant fluorescence at 544 nm in CHCl₃.     

A 2-D nickel coordination polymer with an unsymmetric ligand, 5-(3-pyridyl)-1,3,4-oxadiazole-2-thione

A new nickel coordination polymer was obtained from an unsymmetric building block 5-(3-pyridyl)-1,3,4-oxadiazole-2-thione (HL6) and Ni(NO₃)₂ · 6H₂O-afforded [Ni(L6)₂(H₂O)₂] _n (1) with a (4,4) network. Complex 1 exhibits moderate antimicrobial activity against Bacillus subtilis ATCC 6633 and Candida albicans ATCC 90028. Thermogravimetric data and magnetic moments for 1 have been investigated.     

Reaction ofN-(3,3,3-trifluoro-2-trifluoromethylprop-1-enyl)dimethylamine with MgSO4·7H2O. Synthesis of 4,4-difluoro-5-trifluoromethyl-2-(2,2,2-trifluoro-1-trifluoromethylethyl)-4H-1,3-dioxine andcis/trans-3-dimethylamino-2-trifluoromethacryloyl fluoride

4,4-Difluoro-5-trifluoromethyl-2-(2,2,2-trifluoro-1-trifluoromethylethyl)-4H-1,3-dioxine andcis/trans-3-dimethylamino-2-trifluoromethacryloyl fluoride were obtained by reaction ofN-(3,3,3-trifluoro-2-trifluoromethylprop-1-enyl)dimethylamine with MgSO₄·7H₂O. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1069–1071, May, 1997.     

Two zinc(II) complexes based on indole-3-acetic acid: crystal structures,fluorescence sensors,and ion exchange with mercury(II)

Two new coordination complexes, [Zn(IA)₂(phen)] (1) and [Zn(IA)₂(4,4′-bipy)] _n ?·?C₂H₅OH (2) (IAH?=?indole-3-acetic acid, phen?=?1,10-phenanthroline, 4,4′-bipy?=?4,4′-bipyridine), have been prepared and characterized by single-crystal X-ray diffraction. Complex 1 is mononuclear and 2 presents a 1-D zigzag chain, in which 4,4′-bipy connects the Zn(II) ions. Both complexes show fluorescence emissions and exhibit fluorescence quenching when Hg²⁺ ions are present. ICP, EDS, and SEM experiments reveal that zinc in both complexes can be exchanged by toxic mercury ions.     

Investigation of neoascorbigen

The synthesis of N-methoxyascorbigen (neoascorbigen) — a natural substance from plants of the Cruciferae family — and also N-ethoxyascorbigen is described. In an acidic media under drastic conditions N-alkoxyascorbigens undergo transformations with the release of ascorbic acid and the formation of oligomers of 1-alkoxy-3-methyleneindolenine or with opening of the lactone ring, decarboxylation, and dehydration and the formation of 2-hydroxy-3-(1-alkoxy-3-indolyl)-4-hydroxymethylcyclopent-2-enone. Amides of neoascorbigen, 3-O-methylglycoside of N-ethoxyascorbigen, and the product of the reduction of N-ethoxyascorbigen by sodium borohydride were obtained for the first time.Scientific-Research Institute of the Search for New Antibiotics, Russian Academy of Medical Sciences, Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 178–186, February, 2000.     

ε-Amino acids based on bicyclic skeleton: bicyclo[3.3.0]octane-5-amino-1-carboxylic acids

Tsc-protected ε-amino acids, bicyclo[3.3.0]octane-5-amino-1-carboxylic acids (1), ready to use in the solid-phase synthesis, are prepared from 4,4-diethylcarboxylic bicyclo[3.3.0]oct-2-enone (3), which is available in bulk from 2 through the catalytic Pauson-Khand reaction.     

Syntheses, Supramolecular Structures and Antibacterial Activities of Five Helical Transition Complexes with 5-Chloro-1-phenyl-1H-pyrazole-3,4-dicarboxylic Acid

Five new transition metal complexes [Cu(HL)₂(H₂O)₂] ( 1 ), [Cu(HL)₂(phen)] ( 2 ), [Cu(HL)₂(H₂O)]₂(4,4′‐bipy) ( 3 ), [Zn(HL)₂(H₂O)₂]·(4,4′‐bipy) ( 4 ), [Ag(HL)(4,4′‐bipy)]_n ( 5 ), (H₂L=5‐chloro‐1‐phenyl‐1H‐pyrazole‐3,4‐dicarboxylic acid, phen=1,10‐phenanthroline; 4,4′‐bipy=4,4′‐bipyridine) have been synthesized and characterized. Complexes 1 , 2 and 4 exhibit monomeric structures, 3 shows a dinuclear structure, 5 displays 1D chain structure, and all extend to 3D supramolecular network via rich hydrogen bonds. Complexes 1 , 2 , 3 , 5 comprise single helical chains, while complex 4 generates quadruple‐stranded helical chains. Furthermore, the antibacterial activities of the titled complexes against bacterial species, three Gram positive bacteria (Staphylococcus aureus, Bacillus subtilis and Candida albicans) and two Gram negative bacteria (Escherichia coli and Pseudomonas aeruginosa) were studied and compared to the activities of free ligands by using the microdilution method.