Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• . The second scenario involves the electrochemical formation of a reactive species followed by cycloaddition in a concerted mechanism. The examples presented hereafter are classified according to the reaction type rather than to the resulting type of heterocycle. Among the intramolecular reactions

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

Ambient gold-catalyzed O-vinylation of cyclic 1,3-diketone: A vinyl ether synthesis

• Yumeng Xi,
• Boliang Dong and
• Xiaodong Shi

Beilstein J. Org. Chem. 2013, 9, 2537–2543, doi:10.3762/bjoc.9.288

• cross-coupling reactions [18]. Based on the π-carbophilicity of gold(I), the addition of alcohol to alkyne should provide direct access to the corresponding vinyl ether. However, most of the reported gold-catalyzed O-nucleophile additions to alkynes are intramolecular reactions. No general protocol for

A Lewis acid-promoted Pinner reaction

• Dominik Pfaff,
• Gregor Nemecek and
• Joachim Podlech

Beilstein J. Org. Chem. 2013, 9, 1572–1577, doi:10.3762/bjoc.9.179

• (triphenylphosphano)ruthenium ([RuH2(PPh3)4]) as catalyst has been applied to aliphatic nitriles and alcohols and was similarly used for intramolecular reactions [9]. Schaefer et al. reported a base-catalyzed Pinner reaction, which gave only poor yields because of the setting of an equilibrium [10]. While developing

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• –deprotonation of the arene was hypothesized to explain the mechanism for C–H palladation. Intramolecular reactions involving alkenes The first example of intramolecular indole alkenylation was reported in 1978 by Trost, who applied reaction conditions based on stoichiometric amounts of PdCl2(MeCN)2 and silver

• order to achieve reoxidation of the Pd(0) species to Pd(II). Intramolecular reactions involving arenes Intramolecular arylations by oxidative coupling were investigated by DeBoef and co-workers as a tool for synthesizing heteropolycyclic compounds [80]. The aerobic Pd(II)-catalyzed reaction of the N

Intramolecular carbenoid ylide forming reactions of 2-diazo-3-keto-4-phthalimidocarboxylic esters derived from methionine and cysteine

• Marc Enßle,
• Stefan Buck,
• Roland Werz and
• Gerhard Maas

Beilstein J. Org. Chem. 2012, 8, 433–440, doi:10.3762/bjoc.8.49

• . It is therefore interesting to gather information about the chemoselectivity of these reactive intermediates. For intramolecular reactions, the ring size of the products can make an additional contribution to the observed chemoselectivity. In this study, we have addressed the competition between two

Photochemical and thermal intramolecular 1,3-dipolar cycloaddition reactions of new o-stilbene-methylene-3-sydnones and their synthesis

• Kristina Butković,
• Željko Marinić,
• Krešimir Molčanov,
• Biserka Kojić-Prodić and
• Marija Šindler-Kulyk

Beilstein J. Org. Chem. 2011, 7, 1663–1670, doi:10.3762/bjoc.7.196

• , giving cycloadducts 11 or 12, respectively. We also performed the thermal intramolecular reactions with the starting compounds 3a and 3b. Theoretically the intramolecular 1,3-dipolar cycloaddition of the sydnone moiety, acting as a masked azomethine dipole, and the double bond of the stilbene moiety

• energetically favoured transition state due to a possible secondary π–π interaction of the tolyl and carbonyl groups. Conclusion In photochemical and thermal intramolecular reactions the investigated compounds 3a and 3b, in which the stilbene and sydnone ring are bridged by a methylene group, show the

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• -catalyzed tandem reactions have allowed chemists to assemble diverse complex molecular frameworks more conveniently. 5.1 Sequential inter-and intramolecular reactions Phenanthrenyl ketones are very important subunits in material science and also occur in numerous natural products. A gold-catalyzed cascade

• intermediate 284, followed by the regioselective nucleophilic attack of the nitrile, leading to the formation of 285. Cyclization may occur through resonance structure 286 or 287 followed by final metal de-coordination (Scheme 50). 5.2 Sequential intramolecular reactions Sequential intramolecular reactions

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• has been reported to produce very high yields; however, the lack of regioselectivity in the biradical cyclopropane formation gives the two regioisomers in a ratio of 8:5. Intramolecular reactions The first intramolecular meta photocycloaddition was reported in 1969 by Morrison and Ferree [39]. The

• influence of the incorporation of oxygen in the tether has been reviewed by de Keukeleire [42]. The selectivities mentioned above may change in intramolecular reactions. In this mode, the endo approach of the alkene cannot be achieved without introducing significant strain, which usually outweighs secondary

Formation of macrocyclic lactones in the Paternò–Büchi dimerization reaction

• Junya Arimura,
• Tsutomu Mizuta,
• Yoshikazu Hiraga and
• Manabu Abe

Beilstein J. Org. Chem. 2011, 7, 265–269, doi:10.3762/bjoc.7.35

• results indicate that the intramolecular reactions, which produce 3-alkoxyoxetanes and 2,7-dioxabicyclo[2.2.1]hept-5-ene (Scheme 1 and Scheme 2), are slower than the intermolecular reaction which leads to the preferential formation of 2-alkoxyoxetane C which is followed by a second Paternò–Büchi reaction

Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

• Carolin Fischer and
• Burkhard Koenig

Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10

• -arylations are particularly mild and do not require additional ligands, which facilitates the work-up. However, reaction times can be very long. Ullmann- and Buchwald–Hartwig-type methods have been used in intramolecular reactions, giving access to complex ring structures. All three N-arylation methods have

• using amides and aryl bromides is possible. Both palladium-catalysed and Ullmann-type N-arylation reactions were successfully applied for both inter- and intramolecular reactions. An advantage of the Ullmann-type reactions is the lower cost of catalyst metal salts and ligands. The mildest conditions for

Tether- directed synthesis of highly substituted oxasilacycles via an intramolecular allylation employing allylsilanes

• Peter J. Jervis and
• Liam R. Cox

Beilstein J. Org. Chem. 2007, 3, No. 6, doi:10.1186/1860-5397-3-6

• to adopt an unfavourable pseudoaxial position. It is therefore proposed that these substrates react through poorly-defined T.S.s and consequently exhibit essentially no stereoselectivity. Background Intramolecular reactions offer distinct advantages over their intermolecular counterparts providing