供体-受体氮杂环丙烷碳-碳键断裂的环加成反应研究进展

氮杂环丙烷有两种不同的开环方式:一种是碳-氮键断裂开环,另一种是碳-碳键断裂开环.其中,氮杂环丙烷以碳-氮键断裂的反应已经有很多综述报道.主要概述了近二十年来供体-受体(Donor-Acceptor,D-A)氮杂环丙烷以碳-碳键断裂的环加成反应研究进展.在合适催化剂作用下,D-A氮杂环丙烷经碳-碳键断裂开环形成亚胺叶立德,该叶立德可以和醛、亚胺、烯烃、炔烃和吲哚等发生[3+n]环加成反应.     

过渡金属催化的有机硼酸与不饱和键的加成反应

概述了过渡金属催化的有机硼酸与不饱和键的加成反应,包括铑催化、镍催化、钯催化三部分内容.     

碳碳三键与碘单质的加成反应

对碳碳三键与碘单质反应的有关知识，包括最新的科研成果，进行了详细的讨论。     

不饱和碳碳键电化学加氢的最新研究进展

选择性加氢是有机合成反应中最为经典的反应之一,在天然产物、药物和工业化学品的制造中有着广泛的应用。传统的加氢反应因为其高温高压、危险系数大和使用贵重金属等诸多不利因素,所以人们一直希望能发现更安全温和的加氢反应方法。近年来,由于电化学加氢方法反应条件温和、能量消耗低及反应进程容易控制等优势越来越受到人们的重视,并取得了许多研究成果。本综述依据电化学加氢反应的化学键类型,对近几年来的不饱和碳碳键电化学加氢相关文献报道进行了归纳和综述,有望为电化学加氢研究提供一定指导意义。     

亲核性氟源在碳碳不饱和键选择性氟化官能化反应中的应用

含氟化合物表现出的特殊理化和生物活性使得其在药物、农用化学品和材料科学等领域有着广泛而重要的应用,因此,含氟化合物的高效制备不仅成为了合成化学的研究热点之一,而且极大地推动了相关领域的蓬勃发展.其中,在有机分子内直接引入氟原子的方法主要有亲电氟化和亲核氟化.相较于亲电氟化,亲核氟化反应所用的氟化试剂通常廉价易得,所需的反应条件也比较温和.作者课题组借助过渡金属催化、可见光氧化还原催化和可见光促进策略,拓展了亲核性氟源在碳碳不饱和键选择性氟化官能化反应中的应用,合成了一系列结构新颖的含氟化合物.在该研究评论中将对此做出小结,并对该领域值得关注的研究方向进行简要的展望.     

末端炔烃对碳氧和碳氮双键的加成反应

概述了末端炔烃对碳氧和碳氮双键的加成反应,包括末端炔烃对醛、酮、硝酮、醛亚胺和酮亚胺的加成反应.     

含磷α—碳负离子的相转移催化共轭加成反应

亲核性碳负离子与亲电性碳-碳双键的共轭加成反应是形成新碳-碳键的重要方法.含磷碳负离子的共轭加成反应已有报道,但反应一般都是在强碱作用和无水条件下进行,反应条件比较苛刻,如O,O-二乙基乙酸酯基磷酸酯在金属钾或钠作用下形成碳负离子     

碳碳重键自由基加成反应定位的若干规律问题

着重讨论了自由基加成定位效应指数Ａｆ的提出及应用。运用该指数可以发现，任一自由基在加成反应中，总是进攻碳碳重键上Ａｆ值较小的不饱和碳，或该碳被进攻占优势。两端Ａｆ值差距愈大，则定向专一性愈强；两端Ａｆ值相近，则自由基沿两个位置加成的几率可能相等。     

含P—H键螺环五配位磷化合物的加成反应

5-氢-1,9-二氧-4,6-二氮-5-膦环-[4,4]壬烷1与二硫化碳、异硫氰酸酯反应,分别得到2-巯基二氢噻唑2和2-取代氨基二氢噻唑4,并用动态~(31)P NMR谱研究了其反应机理。     

Metal-catalyzed additions of H-P(O) bonds to carbon-carbon unsaturated bonds

In this short review, we briefly summarize our studies on metal-catalyzed additions of H-P(O) bonds to carbon-carbon unsaturated compounds (alkynes, alkenes, allenes, dienes and related). These new reactions provide regio- and stereoselective ways for the preparation of a variety of organophosphorus compounds. Mechanistic aspects related to the catalytic processes are discussed.     

A Convenient Preparation of Fluorinating Reagent F‐TEDA Bearing Bisphenylsulfonylimide Counterion and Its Fluorination to Oxindoles

The direct preparation of a kind of fluorinating reagent 1 [F‐TEDA‐N(SO₂Ph)₂] was realized in high yield via the complexation of N‐fluorobenzenesulfonimide (NFSI) with 1‐(chloromethyl)‐1,4‐diazabicyclo[2.2.2]octan‐1‐ium N′,N′‐bis‐(benzenesulfonylimide) salt. In its fluorination to oxindoles, the fluorinating products 6 were afforded in moderate to high yields.     

Low-temperature addition of molecular fluorine to unsaturated perfluorohydrocarbons

Calorimetry and ESR Spectroscopy were used to study the low-temperature fluorination (77–300 K) of unsaturated perfluorohydrocarbons. In the solid phase at 77–100 K (glassy or crystalline state) fluorination does not occur. On transition from glassy systems to the overcooled liquid state formation of molecular complexes in which fluorine is attached to the >C=C< bond becomes possible. These complexes are stabilized on crystallization of the system; with a further increase in temperature, efficient addition of molecular fluorine takes place in the crystal phase. However, the addition of fluorine by some chain or carbene mechanism must not be ruled out for such systems. Thus, in the case of hexafluoropropylene trimer, the addition proceeds as a chain reaction producing long-living free radicals at the initial stage.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 292–295, February, 1993.     

Consecutive carbon-carbon bond formation approach in tandem cyclization reactions

The conventional tandem cyclization reactions involve the formation of alternating carbon-carbon bonds, whereas the newly developed cyclization reactions involve the formation of consecutive carbon-carbon bonds, in which N-aziridinylimines have been utilized as geminal radical acceptor and donor equivalents in a single operation. This unprecedented tandem cyclization approach becomes feasible by the successful generation of 5- and 6-membered ring radicals by radical cyclizations of N-aziridinylimines. The same notion can be applied to the anionic cyclizations of N-aziridinylimines, thereby allowing anionic consecutive carbon-carbon bond formation. This approach has great synthetic potential, particularly for the construction of quaternary carbon centers, and it provides highly efficient routes for the synthesis of natural products.     

Stannylation of unsaturated carbon-carbon bonds by tin tetrachloride

The reactions of tin tetrachloride and four terminal alkynes (PhCCH, ^tBuCCH, ⁿBuCCH, HOCH₂CCH), norbornene, and norbornadiene in dichloromethane or chloroform solution lead to the formation of stannylation products, which were characterized by ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. Virtually complete α-regioselectivity was obtained in reaction of all four alkynes without any effect of the relative steric bulk of the substituent R at the triple bond of alkyne RC_βC_αH. The reaction of norbornene and norbornadiene with SnCl₄ is stereoselective, giving an exo stannylation product.     

Chlorodimethylaluminum-promoted nucleophilic addition of lithium pentamethylcyclopentadienide to aliphatic aldehydes and DDQ-mediated carbon-carbon bond cleavage of the adducts providing the parent aldehydes

Treatment of aliphatic aldehyde with lithium pentamethylcyclopentadienide in the presence of chlorodimethylaluminum provided the corresponding carbinol in excellent yield. The carbinol returns to the parent aldehyde and pentamethylcyclopentadiene by the action of a catalytic amount of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ).     

MCSCF study of singlet oxygen addition to ethenol—a model of photooxidation reactions of unsaturated and aromatic compounds bearing hydroxy groups

The reaction path of singlet (¹Δ_g) oxygen addition to ethenol (vinyl alcohol)—a model of the reactions of singlet oxygen with aromatic and unsaturated compounds bearing the hydroxy groups—has been studied by means of MCSCF calculations, using various active spaces and basis sets. The effects of dynamic correlation (at the PT2 level) and basis set superposition error (BSSE) on relative energies were also investigated. It was found that including polarization functions is necessary to obtain geometries of the oxygen moiety consistent with the available experimental data. Two possible reaction products were considered: 1-hydroxy-1,2-dioxethane (peroxide) and 2-hydroperoxyethanal-1 (hydroperoxide); their energies are 24.1 and 36.6 kcal/mol (44.1 and 78.2 kcal/mol with the PT2 contribution and BSSE correction) below the dissociation limit, respectively (all energies reported here refer to the 6-31G** basis set and an active space composed of eight orbitals and ten electrons). A common stage of both reactions is the formation of a peralcoxyl intermediate with one of the oxygen atoms attached to the unsubstituted carbon atom; the energies of the respective transition state and that of the intermediate are 30.2 and 18.7 kcal/mol (15.9 and 10.3 kcal/mol with the PT2 contribution and BSSE correction) above the dissociation limit, respectively. The energy of this transition state is the dominant energy barrier to the reaction. The intermediate can then undergo conversion to the dioxethane product, to the perepoxide intermediate, or via a proton transfer, directly to the hydroperoxide, the last route being the most probable one. The perepoxide intermediate, after a proton transfer, also readily gives the hydroperoxide. It was also found that the unimolecular conversion from dioxethane to hydroperoxide via a proton transfer from the hydroxy group accompanied with ring cleavage requires an activation energy of at least 56 kcal/mol, making this reaction path highly improbable. © 1997 John Wiley & Sons, Inc. J Comput Chem 18 : 1668–1681, 1997     

Stereoselective conjugate addition reactions to phenylglycinol-derived, unsaturated oxazolopiperidone lactams

Phenylglycinol-derived, unsaturated oxazolopiperidone lactams are extremely useful building blocks that undergo stereoselective conjugate addition reactions with organocuprates, enolates, and sulfur-stabilized anions, allowing the stereocontrolled introduction of substituents at the piperidine 4-position. The factors governing the exo- or endo-facial selectivity are discussed. The methodology can be used for the preparation of a variety of enantiopure piperidines, including pharmaceuticals, alkaloids precursors, piperidine-fused derivatives, as well as complex piperidine-containing natural products.     

Homolytic addition of benzyl bromide to unsaturated compounds in conditions of metal-complex initiation

Radical addition of benzyl bromide to unsaturated compounds containing substituents of a different polar nature, CH₂=CHX (X=C₄H₉, SiMe₃, CF₃, CO₂Me, CN, H), was conducted in the presence of the Fe(CO)₅ + DMF (HMPA) system. Adducts were obtained and their structure was demonstrated by¹³C NMR and mass spectrometry.A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2347–2352, October, 1992.     

Oxidative addition of heteroaromatic halides to Negishi reagent and subsequent cross-coupling reactions

Heteroarylzirconocene halides were prepared via the oxidative addition of heteroaryl halides to the Negishi reagent ‘Cp₂ZrBu₂’. The palladium-catalyzed cross-coupling of the in situ generated organozirconium reagents with functionalized aryl and heteroaryl halides proceeded smoothly in the presence of CuCl to produce the cross-coupling products in high yields.