Reaction of 3-hydrazono-1,1,1-trifluoro-2-alkanones with lawesson reagent accessing 6-trifluoromethyl-3,6-dihydro-2H-[1,3,4]thiadiazines | CiNii Research 検索 タイトル 人物/団体名 著者ID/研究者番号 所属機関 ISSN DOI 期間 〜 本文リンク 本文リンクあり データソース JaLC IRDB Crossref DataCite NDLサーチ NDLデジコレ（旧NII-ELS） RUDA JDCat NINJAL CiNii Articles CiNii Books NACSIS-CAT/ILL DBpedia KAKEN e-Rad Integbio PubMed LSDB Archive 極地研ADS 極地研学術DB OpenAIRE 公共データカタログ すべて 研究データ 論文 本 博士論文 プロジェクト 人物 > 人物検索機能について 詳細検索 閉じる CiNii Researchナレッジグラフ検索機能（試行版）をCiNii Labsにて公開しました 「研究データ」「根拠データ」の収録について CiNii Books機能統合対応の追加実施をいたしました Reaction of 3-hydrazono-1,1,1-trifluoro-2-alkanones with lawesson reagent accessing 6-trifluoromethyl-3,6-dihydro-2H-[1,3,4]thiadiazines DOI DOI Yasuhiro Kamitori Tomoko Sekiyama Etsuji Okada 書誌事項 公開日 2007-01-01 DOI 10.1016/s0385-5414(07)81097-5 10.3987/com-07-11124 公開者 CLOCKSS Archive この論文をさがす CiNii Books 説明 - The reaction of 3-dimethylhydrazono-1,1,1-trifluoro-2- alkanones (1) with Lawesson reagent affording 6-trifluoromethyl-3,6-dihydro-2H-[1,3,4]thiadiazines (4) was elucidated in detail. The results indicate [1,5]sigmatropic hydrogen shift from N-methyl group to thiocarbonyl carbon on 3-dimethylhydrazono-1,1,1-trifluoro-2-alkanethiones (5) should readily proceed as a key step in this cyclization reaction. Similar [1,5]sigmatropic hydrogen shift on selenium analogues of 1 as well as that on imines derived from 1 are also studied on the basis of molecular orbital calculations.

This chapter discusses sigmatropic rearrangements that are defined by the movement of a σ-bond from one position to another. It describes one main family wherein a single group, or an atom, moves from one end of a conjugated system n atoms along to the other end. Rearrangements of this kind are labelled as [1,n] shifts. The migrating bond moves from C-1 to C-n along the conjugated system, and the ‘1’ comes from the fact that the bond remains attached to the same atom R. The chapter explains that pericyclic sigmatropic rearrangements are mostly shifts of hydrogen atoms, of which some have a total of (4n + 2) electrons involved and some (4n). It covers the differences between suprafacial and antarafacial [1,n] rearrangements before turning to rearrangements in which the bond moves m atoms along a conjugated system at the other end—the most important type of rearrangement of the [m,n] category.

Here, we report a novel bimolecular reaction pathway forming the resonance-stabilized fulvenallenyl radical (C 7 H 5 ) via the gas-phase reaction of tricarbon (C 3 , X 1 Σ g + ) with 1,3-butadiene (C 4 H 6 , X 1 A g ). Crossed molecular beam experiments combined with high-level electronic structures and statistical calculations reveal a rich potential energy surface. The reaction proceeds via tricarbon addition to a double bond of 1,3-butadiene, overcoming a 30 kJ mol –1 barrier, followed by ring closure, isomerizations (ring opening/closures, hydrogen shifts), and eventual hydrogen atom loss, yielding the fulvenallenyl radical (p1) almost exclusively via two dominant pathways. Considering the entrance barrier, this reaction may occur in high-temperature environments, like circumstellar envelopes of carbon stars, but is suppressed in colder regions such as molecular clouds and Titan’s atmosphere. These findings highlight the unexpected reactivity of small carbon clusters in shaping the molecular complexity of our universe, from the flicker of a flame to the death of a star.

so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bond The E2 mechanism also requires a base, but there the attack of the base and the elimination of the leaving group proceed simultaneously and produce no ionic intermediate. In contrast to the E1 eliminations, different stereochemical configurations are possible for the reaction product in the E2 mechanism, because the attack of the base preferentially occurs in the anti-position with respect to the leaving group. Because of the similar conditions and reagents, the E2 elimination is always in competition with the SN2-substitution. Nucleophil… In a rearrangement reaction, the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. These include hydride shift reactions such as the Wagner-Meerwein rearrangement, where a hydrogen, alkyl or aryl group migrates from one carbon to a neighboring carbon. Most rearrangements are associated with the breaking and formation of new carbon-carbon bonds. Other examples are sigmatropic reaction such as the Cope rearrangement. Cyclic rearrangements include cycloadditions and, more generally, pericyclic reactions, wherein two or more double bond-containing molecules form a cyclic molecule. An important example of cycloaddition reaction is the Diels–Alder reaction (the so-called [4+2] cycloaddition) between a conjugated diene and a substituted alkene to form a substituted cyclohexene system. Whether a certain cycloaddition would proceed depends o The E2 mechanism also requires a base, but there the attack of the base and the elimination of the leaving group proceed simultaneously and produce no ionic intermediate. In contrast to the E1 eliminations, different stereochemical configurations are possible for the reaction product in the E2 mechanism, because the attack of the base preferentially occurs in the anti-position with respect to the leaving group. Because of the similar conditions and reagents, the E2 elimination is always in competition with the SN2-substitution. Nucleophilic addition of a carbanion or another nucleophile to the double bond of an alpha, beta-unsaturated carbonyl compound can proceed via the Michael reaction, which belongs to the larger class of conjugate additions. This is one of the most useful methods for the mild formation of C–C bonds. Some additions which can not be executed with nucleophiles and electrophiles can be succeeded with free radicals. As with the free-radical substitution, the radical addition proceeds as a In a rearrangement reaction, the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. These include hydride shift reactions such as the Wagner-Meerwein rearrangement, where a hydrogen, alkyl or aryl group migrates from one carbon to a neighboring carbon. Most rearrangements are associated with the breaking and formation of new carbon-carbon bonds. Other examples are sigmatropic reaction such as the Cope rearrangement. Cyclic rearrangements include cycloadditions and, more generally, pericyclic reactions, wherein two or more double bond-containing molecules form a cyclic molecule. An important example of cycloaddition reaction is the Diels–Alder reaction (the so-called [4+2] cycloaddition) between a conjugated diene and a substituted alkene to form a substituted cyclohexene system. Whether a certain cycloaddition would proceed depends on the electronic orbitals of the participating species, as only orbitals with the same sign of wave function will overlap and interact constructively to form new bonds. Cycloaddition is usually assisted by light or heat. These perturbations result in a different arrangement of electrons in the excited state of the involved molecules and therefore in different effects. For example, the [4+2] Diels-Alder reactions can be assisted by heat whereas the [2+2] cycloaddition is selectively induced by light. Because of the orbital character, the potential for developing stereoisomeric products upon cycloaddition is limited, as described by the Woodward–Hoffmann rules. Biochemical reactions are mainly controlled by complex proteins called enzymes, which are usually specialized to catalyze only a single, specific reaction. The reaction takes place in the active site, a small part of the enzyme which is usually found in a cleft or pocket lined by amino acid residues, and the rest of the enzyme is used mainly for stabilization. The catalytic action of enzymes relies on several mechanisms including the molecular shape ("induced fit"), bond strain, proximity and orientation of molecules relative to the enzyme, proton donation or withdrawal (acid/base catalysis), electrostatic interactions and many others. The biochemical reactions that occur in living organisms are collectively known as metabolism. Among the most important of its mechanisms is the anabolism, in which different DNA and enzyme-controlled processes result in the production of large molecules such as proteins and carbohydrates from smaller units. Bioenergetics studies the sources of energy for such reactions. Important energy sources are glucose and oxygen, which can be produced by plants via photosynthesis or assimilated from food and air, respectively. All organisms use this energy to produce adenosine triphosphate (ATP), which can then be used to energize other reactions. Decomposition of organic material by fungi, bacteria and other micro-organisms is also within the scope of biochemistry.

Recent lab. and field expts. indicate that the autoxidn. of volatile orgs. play a significant role in the formation and growth of secondary org. aerosol particles in the atm. This autoxidn. process is initiated by an oxidant such as OH or O₃, and propagates by hydrogen shift reactions of peroxy radical intermediates followed by subsequent oxygen addn., as illustrated in the figure. We have used an exptl. verified theor. approach based on Multi-Conformer Transition State Theory (MC-TST), including Eckart tunneling, to calc. temp. dependent rate coeffcients of peroxy radical H-shift reactions. W