Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• Heck coupling: In 2003, Snieckus and co-workers [97] have synthesized the seco-C/D ring analogues of ergot alkaloids through the intramolecular Heck reaction as a key step. The coupling precursors 63 and 68 were prepared from 4-bromoindoles by a sequential Vilsmeier–Haack, Henry nitroaldol condensation

Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

• Matthieu Jouffroy,
• Rafael Gramage-Doria,
• David Sémeril,
• Dominique Armspach,
• Dominique Matt,
• Werner Oberhauser and
• Loïc Toupet

Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249

• -catalysed Mizoroki–Heck coupling reactions between aryl bromides and styrene on one hand, and the rhodium-catalysed asymmetric hydroformylation of styrene on the other hand. The inability of both chiral ligands to form standard bis(phosphine) complexes under catalytic conditions was established by high

• Mizoroki–Heck and asymmetric hydroformylation reactions. The related trans-chelating diphosphine WIDEPHOS (Figure 1) was also tested for comparison purposes in the case of the Mizoroki–Heck coupling studies. Results and Discussion Metal coordination As shown previously, HUGPHOS-1 and HUGPHOS-2 are able to

• enantioselectivities probably arise from the embracing properties of the HUGPHOS ligands, which facilitates chirality transfer. Heck cross-coupling Phosphine-assisted Heck reactions strongly depend on the bulkiness of the phosphine used [64]. To assess HUGPHOS-2 in Heck coupling, we focused on the reaction between

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• desired DVCPR in almost quantitative yield at elevated temperature, followed by removal of the silyl-protecting group under acidic conditions to furnish cycloheptenone 70. Standard functional group interconversion furnished diolefin 71. Subjection of this compound to Heck coupling conditions resulted in

• in the formation of a bridged tetracycle after initial Heck coupling followed by carbo-palladation and subsequent β-hydride elimination [69][70][71]. Double bond regioisomers (between C7 & C8 or C13 & C14) were obtained. Oxidation with DDQ yielded the 1,6-unsaturated ketone 72. Selective epoxidation

Oxidative 3,3,3-trifluoropropylation of arylaldehydes

• Akari Ikeda,
• Masaaki Omote,
• Shiho Nomura,
• Miyuu Tanaka,
• Atsushi Tarui,
• Kazuyuki Sato and
• Akira Ando

Beilstein J. Org. Chem. 2013, 9, 2417–2421, doi:10.3762/bjoc.9.279

• aldehydes in the presence of fluoride anion [29]. Recently, Prakash et al. [30] reported the synthesis of β-trifluoromethylstyrenes through a Heck coupling reaction of aryl iodides with 1-iodo-3,3,3-trifluoropropane, allowing a direct introduction of 3,3,3-trifluoropropenyl groups to aromatic rings

Intramolecular carbonickelation of alkenes

• Rudy Lhermet,
• Muriel Durandetti and
• Jacques Maddaluno

Beilstein J. Org. Chem. 2013, 9, 710–716, doi:10.3762/bjoc.9.81

• aryl ether 6a, underlines that the endocyclic character of the unsaturation is essential to favor the Heck coupling. The carbonickelation process leads to a secondary alkylnickel intermediate, which is sufficiently stabilized to avoid the side reactions observed above. Actually, the carbonickelation

• silver carbonate avoids these post-cyclization isomerizations [34][35], but the yield (52% after 16 h) was not higher than with nickel. Thus, this study suggests that a Heck-coupling reaction relying on a carbonickelation step can be considered as a useful tool in the total synthesis. Conclusion In this

Iridium-catalyzed intramolecular [4 + 2] cycloadditions of alkynyl halides

• Andrew Tigchelaar and
• William Tam

Beilstein J. Org. Chem. 2012, 8, 1765–1770, doi:10.3762/bjoc.8.201

• reactions to gain access to complex bicyclic molecules that would not be accessible directly by cycloaddition. Previous work has demonstrated this synthetic utility by the further functionalization of 2a by Pd-catalyzed Suzuki and Heck coupling reactions [33]. In theory any of the cycloadducts 2 could

Branching out at C-2 of septanosides. Synthesis of 2-deoxy-2-C-alkyl/aryl septanosides from a bromo-oxepine

• Supriya Dey and
• Narayanaswamy Jayaraman

Beilstein J. Org. Chem. 2012, 8, 522–527, doi:10.3762/bjoc.8.59

• , Heck, Suzuki and Sonogashira coupling reactions. Heck coupling reactions [24][25] were undertaken first. Thus, the reaction of bromo-oxepine 2 with methyl acrylate was performed, in the presence of Pd(OAc)2 (10 mol %) and Cs2CO3 in 1,4-dioxane, at 98 °C (Scheme 1), to afford diene 3, in 70% yield. The

• substrate presenting two acrylates within the molecule, styrene, and α-methyl styrene (Scheme 1). Reactions with these substrates also afforded the diene products 4–7, in good yields. The anticipated two Heck coupling reactions with the substrate that presents two acrylates, could not be achieved, rather

• only the mono-Heck coupling product 5 was obtained. Alternative reaction conditions were attempted, for example, by using Pd(PPh3)2Cl2 (10 mol %), instead of Pd(OAc)2, while keeping other parameters of the reaction uniform, yet the double-Heck coupling product was not observed. The newly generated

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• very interested in the Heck coupling of N-alkyl vinazenes with various (hetero)aromates [115]. This synthetic interest resulted in four new diimidazole compounds 112–115 (Figure 20). This series of basic π-conjugated compounds was significantly extended in 2009 by a library of various π-linkers [116

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor

• Bernhard Gutmann,
• Toma N. Glasnov,
• Tahseen Razzaq,
• Walter Goessler,
• Dominique M. Roberge and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2011, 7, 503–517, doi:10.3762/bjoc.7.59

• publication we reported the Mizoroki–Heck coupling of 4-iodobenzonitrile (12) with n-butyl acrylate (13) under high-temperature continuous flow conditions (150–190 °C) employing Pd(OAc)2 as a homogeneous pre-catalyst and a stainless steel-based coil flow system (Scheme 4) [59]. With only 0.01 mol % of Pd(OAc

• extensive washing regime with pure solvent. This became very obvious, since running the Mizoroki–Heck coupling shown in Scheme 4 without any added Pd catalyst still led to complete conversion in subsequent flow experiments utilizing the same coil. Control experiments in batch mode confirmed that the

• , must also be carefully considered in executing flow chemistry. In the case of a Mizoroki–Heck coupling, we have demonstrated that small amounts of Pd metal retained inside a stainless steel reactor can exhibit catalytic activity in subsequent chemical transformations. As most microreactors for high

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• rather weak (Φ ~15–35%), the maximum appeared at about 700–720 nm in the solid state. By Heck coupling it was possible to synthesize a polyarylenevinylene-type polymer P-13, the arylene units alternatingly being phenylenevinylene and diphenylDPP (Table 2) [36]. The polymer was obtained upon Pd-catalyzed

Pd-catalyzed decarboxylative Heck vinylation of 2-nitrobenzoates in the presence of CuF₂

• Lukas J. Gooßen,
• Bettina Zimmermann and
• Thomas Knauber

Beilstein J. Org. Chem. 2010, 6, No. 43, doi:10.3762/bjoc.6.43

• decarboxylated at a palladium catalyst. The coupling of electron-poor 2-nitrobenzoates was achieved by combining a copper-mediated decarboxylation with a palladium-catalyzed Heck coupling. The new mechanistic pathway is likely to open up new perspectives for decarboxylative Heck reactions by overcoming some

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• the C10 hydroxymethyl to complete the mitomycin carbon backbone (Scheme 56). However, compound 206 was very unstable with a half-life of 1.5 days at −15 °C. 7.2. Rapoport. Intramolecular Heck coupling In 1983 Rapoport released a fascinating synthesis of aziridinomitosenes based on a photochemical

• coupling Recently the Michael group proposed a formal enantioselective asymmetric synthesis of an aziridinomitosene also based on an intramolecular Heck coupling [150]. They succeeded in incorporating all the reactive functionalities, namely the quinone, the carbamate and the aziridine and thus bypassed

• unnatural regioisomer 214 as the major product. Because carbon C2 in quinone 211 is more electrophilic than carbon C1, nucleophilic addition-elimination of vinylogous carbamate 212 at the carbon centre gave intermediate 213 which cyclized in situ to give compound 214. 7.3. Michael. Intramolecular Heck

From discovery to production: Scale- out of continuous flow meso reactors

• Peter Styring and
• Ana I. R. Parracho

Beilstein J. Org. Chem. 2009, 5, No. 29, doi:10.3762/bjoc.5.29

• Suzuki and Heck coupling reactions at elevated temperatures while the nickel catalyst is active in the Kumada coupling [11][12] reaction at room temperature in batch (Scheme 1) and continuous flow reactors. In the latter, the catalyst is packed into a 3 mm diameter glass reactor tube of length 25 mm and

Convenient methods for preparing π-conjugated linkers as building blocks for modular chemistry

• Jiří Kulhánek,
• Filip Bureš and
• Miroslav Ludwig

Beilstein J. Org. Chem. 2009, 5, No. 11, doi:10.3762/bjoc.5.11

• . Overall 12 extended π-linkers have been easily synthesized (8 of them are new compounds) utilizing procedures such as a lithiation/reaction with triisopropyl borate/esterification with pinacol, Mizoroki–Heck coupling with vinylboronate pinacol ester, borylation with bis(pinacolato)diboron or Sonogashira