Continuous-flow hydration–condensation reaction: Synthesis of α,β-unsaturated ketones from alkynes and aldehydes by using a heterogeneous solid acid catalyst

• Magnus Rueping,
• Teerawut Bootwicha,
• Hannah Baars and
• Erli Sugiono

Beilstein J. Org. Chem. 2011, 7, 1680–1687, doi:10.3762/bjoc.7.198

• was purified by column chromatography (n-hexane/DCM [2:1 to 1:1]). The schematic arrangement of the continuous-flow system. Preparation of chalcone 3b on larger scale. Optimization of hydration–condensation reactions.a Flow hydration–condensation of alkynes 1 and aldehydes 2.a Supporting Information

Continuous flow hydrogenation using polysilane-supported palladium/alumina hybrid catalysts

• Hidekazu Oyamada,
• Takeshi Naito and
• Shū Kobayashi

Beilstein J. Org. Chem. 2011, 7, 735–739, doi:10.3762/bjoc.7.83

• double and triple bonds in various substrates are shown in Table 1; these proceeded quantitatively at room temperature under neat conditions. The products were obtained at approximately 10 g/h through the 4 cm3 column. The hydrogenation reactions of trans-stilbene and trans-chalcone, as representative

• solid substrates (Scheme 2), were also examined. The substrates were dissolved in toluene or ethyl acetate. The reduction of trans-stilbene proceeded quantitatively, but an overreaction product was obtained (7% yield) in the reduction of trans-chalcone. We then investigated the hydrogenation of a nitro

• , CDCl3) δ 7.46–7.50 (m, 2H), 7.60–7.63 (m, 1H), 8.12–8.14 (m, 2H). Schematic diagram of the continuous flow reactor (left) and the column top (right). Hydrogenation of ethyl cinnamate. Hydrogenation of trans-stilbene and trans-chalcone. Hydrogenation of nitrobenzene and deprotection of the Cbz group

An expedient and new synthesis of pyrrolo[1,2-b]pyridazine derivatives

• Rajeshwar Reddy Sagyam,
• Ravinder Buchikonda,
• Jaya Prakash Pitta,
• Himabindu Vurimidi,
• Pratap Reddy Padi and
• Mahesh Reddy Ghanta

Beilstein J. Org. Chem. 2009, 5, No. 66, doi:10.3762/bjoc.5.66

• -methyl-3-oxo-pentanoic acid phenylamide with tertiary butyl carbazate and subsequent condensation of the resulting carbamate derivative with a chalcone provided a facile new approach to pyrrolo[1,2-b]pyridazine derivatives. Keywords: 1,4-diketone; migration and cyclization; pyrrolo[1,2-b]pyridazine

• [1,2-b]pyridazine-5-carboxylic acid phenylamide 5a. A plausible mechanistic pathway for the formation of compounds 6a–j involves hydrolysis and decarboxylation of carbamate 3, subsequent condensation with chalcone 4a–j to provide alkenyl imine 9, its sequential hydrolysis and decarboxylation, followed

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

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

An improved synthesis of 1,3,5-triaryl- 2-pyrazolines in acetic acid aqueous solution under ultrasound irradiation

• Ji-Tai Li,
• Xiao-Hui Zhang and
• Zhi-Ping Lin

Beilstein J. Org. Chem. 2007, 3, No. 13, doi:10.1186/1860-5397-3-13

• ratio to 1:2, and 1:3 the yields of 3a increased to 82% and 89% respectively (Table 1, Entry b, c). The results showed that changing the molar ratio of 1:2 had a significant effect on the yield, and the optimum molar ratio of chalcone: phenylhydrazine was 1:3. The important discovery was that in the

• decreased from 96% to 95% and 92% respectively (Table 1, Entry d, e, f). So the reaction conditions we chose were: the molar ratio of chalcone: phenylhydrazine: sodium acetate was 1:3:0.15. In order to verify the effect of ultrasound irradiation, in the absence of ultrasound, we have performed the reaction

• of chalcone with phenylhydrazine hydrochloride by refluxing at 108°C for 4 h. The yield of pyrazoline was 76% (Table 1, Entry i). While under ultrasound irradiation, the reaction can be completed within 2 h in 96% yield at room temperature (Table 1, Entry d). It was clear that the ultrasound could