Regio- and stereoselective ring-opening reactions of cyclopropenones. α-methylene-γ-butyrolactones via additions of trichlorocyclopropenylium ions to alkenes

The 2-chloro-3-(2′-chloroalkyl)cyclopropenones 4, readily obtained by hydrolysis of the adducts of the trichlorocyclopropenylium ion onto alkenes, thermally rearrange to propiolic acid chlorides 6. Treatment of 4 with TosOH·H2O in CH2Cl2 yields the (E)-3-chloro-2-(2′-chloroalkyl)acrylic acids 9, which have been converted in two simple steps to -methylene-γ-butyrolactones 11 with good overall yields

Addition reactions of the trichlorocyclopropenylium ion with alkenes. A novel access to cyclopropene and cyclopropenone derivatives

Trichlorocyclopropenylium tetrachloroaluminate 1+-AlCl−4 reacts with alkenes in nitromethane at −35°C to give the 1:1 addition products 2+-AlCl−4, which can be converted into the 2-chlorocyclopropenones 5 or the ä,β-acetylenic carboxylates 6

4,5,12,13-Tetrabromo[2.2]paracyclophane - A New Bis(aryne) Equivalent

The reaction of 2 with nBuLi at -78°C generates aryne intermediates within the aromatic rings of [2.2]paracyclophane which are trapped in Diels-Alder reactions with dienes like furan, 1,9-diphenylisobenzofuran, or cyclopentadiene. Reductive deoxygenation with low-valent titanium reagents or TMSI converts the adducts of furan and isobenzofuran into anti-[2.2]paracyclophanes 4 and 5, respectively. The reaction of two aryne intermediates with [2.2](2,5)furanophane (7) yields 8 with three [2.2]paracyclophane units arranged in a stair-like fashion; yet, in this compound the highly shielded oxygen atoms cannot be removed anymore by reduction

[2.2](4,7)Isobenzofuranophanes - Synthesis, Characterisation and Reactivity

The isomeric Diels-Alder adducts 3, obtained by cycloaddition of tetraphenylcyclopentadienone to the 4,5:12,13-bis-(oxanorbornadieno)[2.2]paracyclophanes syn,syn- and anti,-syn-2[Note ][The stereochemical descriptors syn and anti refer to the orientation of the oxygen bridge in the oxabicyclo[2.2.1]heptadiene subunits with respect to the [2.2]paracyclophaneskeleton.], yield the unstable isobenzofuranophane 4 by consecutive extrusion of carbon monoxide and tetraphenylbenzene when heated to 180°C. The molecular ion of 4 was observed in the EI mass spectrum. The stable tetraphenyl-substituted analogue 10 was synthesized independently from the previously unknown 4,5,12,13-tetrabenzoyl[2.2]paracyclophane (9). UV/Vis as well as fluorescence spectra and an X-ray crystal structure analysis of 9 are reported

Учёт и анализ движения основных средств

Объектом исследования является ООО «ТДК-СИБИРЬ». Цель работы – разработка рекомендаций по улучшению технического состояния и обеспеченности основными средствами ООО «ТДК-СИБИРЬ». В дипломной работе рассматривались теоретические аспекты бухгалтерского учет аосновных средств, и практические – анализа наличия и движения основных средств. В ходе выполнения дипломной работы рассмотрены теоретические аспекты бухгалтерского учета основных средств в РФ, рассмотрен бухгалтерский учет наличия и движения основных средств ООО «ТДК-СИБИРЬ», проведен анализ наличия и движения основных средств, а также даны рекомендации по улучшению технического состояния и обеспеченности основных средств.The object of this study is LLC "TDK-Siberia". Purpose - to develop recommendations to improve the technical condition and security of the main means of "TDK-Siberia". The research paper examines the theoretical aspects of accounting aosnovnyh tools and practical - the analysis of the presence and movement of fixed assets. In the course of the thesis deals with the theoretical aspects of accounting of fixed assets in the Russian Federation, considered the accounting the presence and movement of fixed assets of "TDK-Siberia", analyzes the presence and movement of fixed assets, as well as recommendations for improvement of the technical condition and security of fixed assets

Limitations in determining enantiomeric excess of alcohols by 31P-NMR of the phosphonate derivatives

The use of diastereomeric alcohol dialkylphosphonate derivatives to determine the enantiomeric excesses via 31P-NMR signal ratios of anisochronous meso and threo isomers was successfully applied to secondary alcohols (Feringa s method). Expansion of the methodology to primary alcohols possessing the hydroxyl groups thethered to the stereogenic centers by two or more methylene groups proved the method to be inefficent. The comparison between the coupled and decoupled spectra is important in order to identify the signals corresponding to the dialkylphosphonates. Nevertheless the methodology should be applied whenever the amount of the alcohol and its structure are not the limiting factors.O uso de derivados fosfonatos de dialquila diastereoisoméricos na determinação de excessos enantioméricos através da razão entre os sinais de 31P-NMR anisócronos dos isômeros meso e treo, foi bem sucedido para álcoois secundários (método de Feringa), porém revelou-se ineficiente para álcoois primários com dois ou mais grupos metilênicos entre as hidroxilas e os centros estereogênicos. Observou-se adicicionalmente que era importante obter os espectros acoplados e desacoplados para se certificar dos picos correspondentes aos fosfonatos de dialquila. Entretanto, esta metodologia merece ser aplicada sempre que a quantidade de álcool disponível e sua estrutura não forem fatores limitantes.293298Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Paramagnetic Redox Stages of a Bisphane: An ESR and ENDOR Study

Seven redox stages, the dication 12+, the radical cation , the neutral 1, the radical anion , the dianion 12-, the radical trianion , and the tetraanion 14-, are indicated by cyclic voltammetry for the bisphane 1, in which the benzene decks of two lateral paracyclophane moieties are orthogonal to the plane of anthracene framework. In and , the unpaired electron is accommodated into the central anthracene subsystem, and the same statement holds for the two positive or negative charges in 12+ and 12-. Formation of and 1- occurs through admission of additional electrons one-by-one into the two paracyclophane moieties flanking the doubly charged anthracene subsystem in 12-. The above-postulated, successive release or uptake of electrons by the individual parts of the bisphane is in perfect accord with the hyperfine data determined by ESR and ENDOR spectroscopy for , , , as well as for radical ions of suitable reference compounds

Three Paramagnetic Reduction Stages of Phenyl Substituted 1,2:9,10 Dibenzo[2.2]paracyclophane-1,9-dienes. Radical Anions, Triplet Dianions and Radical Trianions as studied by ESR and ENDOR Spektroscopy

Reduction of di- and tetraphenyl-substituted 1,2:9,10-dibenzo[2.2]paracyclophane-1,9-dienes, 3, 3-d'₂, 4,5, and 5-tBu₄ with potassium in ethereal solvents has been monitored by ESR and ENDOR spectroscopy. In each case, the first reduction step yields a radical anion in which the unpaired electron resides in one of the two lateral biphenyl or o-terphenyl mystems orthogonal to the central phane unit. Except under conditions of strong association with the K⁺ counterion, electron exchange between the two π-ystems is fast on the hyperfine time scale. Upon further reduction, a second electron is taken up, as revealed by the appearance of triplet dianions bearing one unpaired electron in each of the two lateral π-ystems (separation ca. 1 nm). The singlet state of the dianion of 5 has been estimated to lie only slightly higher (ca. 2 kJ mol⁻¹) than the triplet state; the simultaneous presence of the singlet dianions of 3 and 5 in the solutions is compatible with evidence from NMR spectroscopy. An even more prolonged contact with potassium metal leads to radical trianions with the unpaired electron accommodated in the central phane unit. These radical trianions can thus be regarded as the radical anions of [2.2]paracyclophane having two negatively charged lateral π-ystems attached to it. Detection of trianions in a quartet state by ESR spectroscopy proved to be difficult under the experimental conditions used. The sequential uptake of three electrons by 3-5 is discussed in the light of the reduction potentials of the constituent π-ystems