Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• used. A proper choice of catalyst and reaction conditions is also needed to improve the efficiency of each reaction (Scheme 18) [18]. Consecutive one-pot transformations initiated by Heck reaction and terminated by intramolecular aza–Michael addition were developed by Hanson and coworkers to access a

Evaluation of a commercial packed bed flow hydrogenator for reaction screening, optimization, and synthesis

• Marian C. Bryan,
• David Wernick,
• Christopher D. Hein,
• James V. Petersen,
• John W. Eschelbach and
• Elizabeth M. Doherty

Beilstein J. Org. Chem. 2011, 7, 1141–1149, doi:10.3762/bjoc.7.132

• (Figure 7). It should be noted that Kappe observed a “Pd mirror” due to soluble Pd leaching from a CatCart® during a continuous flow Mizorki–Heck reaction [24]. In comparison, the fine black precipitate seen in our wash experiment is more consistent with solid Pd/C catalyst. The experiment was repeated

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

• of 1.0 mm i.d. coil) was “loaded” with Pd by processing ≈2 mL of the Mizoroki–Heck reaction mixture through the coil under reaction conditions (180 °C, 1.6 mL/min flow rate) with 1 mol % of the Pd(OAc)2 as pre-catalyst. As expected, the desired product 14 was obtained in 94% isolated yield after

• relatively low (Table 2, entries 1 and 2), significantly higher levels of Pd were found in samples derived from the Mizoroki–Heck reaction mixture (Table 2, entry 3). These results, both in terms of decreasing conversion and Pd leaching are therefore analogous to the experiments using Pd/C as a heterogeneous

• . Only renewed loading of the coil by running a Mizoroki–Heck reaction with Pd(OAc)2 or by simply processing a Pd(OAc)2 solution through the coil at elevated temperature regenerated the “palladated” stainless steel coils. Influence of pressure on reaction rate in flow reactors In the resistively heated

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

• sulfonamides, all prepared in high yields. As this route employs sulfonamide-stabilised anions the preparation and handling of unstable sulfonyl chloride intermediates is therefore circumvented (Scheme 14) [17]. An analogous Heck reaction approach has also been employed to introduce a homologous side chain as

• eletriptan (Scheme 20). A rather ingenious Mitsunobu coupling reaction has been used to create a highly functionalised substrate 96 for an intramolecular Heck reaction resulting in a very short and succinct synthesis of eletriptan and related analogues 97 [29] (Scheme 21). Interestingly, it was found that

• serotonin 5-HT3 receptor antagonist ondansetron (119, Zofran). In this synthesis a palladium-catalysed intramolecular Heck-reaction was used to build the tricyclic indole core in a short and concise sequence (Scheme 26) [35][36]. Alternatively, a direct Fischer indole synthesis between phenylmethyl

Studies on Pd/NiFe₂O₄ catalyzed ligand-free Suzuki reaction in aqueous phase: synthesis of biaryls, terphenyls and polyaryls

• Sanjay R. Borhade and
• Suresh B. Waghmode

Beilstein J. Org. Chem. 2011, 7, 310–319, doi:10.3762/bjoc.7.41

• reactions was demonstrated [40]. The most important paradigm of this reaction is the easy removal of catalyst from the reaction mixture by employing an external magnetic field. We recently reported the filtration-free magnetically separable Pd/NiFe2O4 catalyst for the Heck reaction [41]. Herein, we report

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

• ][18]. We developed a process in which benzoic acids are activated by esterification with electron-poor phenols with the loss of water [19]. The esters are then subjected to a decarbonylative Heck reaction to yield vinyl arenes, CO and the phenols, which can be used in further reaction cycles. In a

• related approach, the benzoic acids activated as isopropenyl esters undergo a decarbonylative Heck reaction that yields the vinyl arenes along with CO and acetone [20]. Since no base is added, only volatile by-products are generated instead of waste salts, and the amount of solvent can be minimized. Myers

• and co-workers introduced another version of the Heck reaction in 2002, in which they converted mostly electron-rich aromatic carboxylic acids and alkenes to vinyl arenes with the release of CO2 [21][22][23]. This decarboxylative Heck reaction allows the direct conversion of benzoic acids without

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

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

• oxidation and an intramolecular Heck reaction [149]. Exposure of the quinone 207 to sunlight triggered the formation of benzoxazole 208, which cleaved to form an intermediate iminium salt. Subsequent proton transfer gave the vinylogous carbamate 209 (Scheme 57). After oxidation of the hydroquinone to the