Enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes catalyzed by binaphthyl-derived organocatalysts

• Saet Byeol Woo and
• Dae Young Kim

Beilstein J. Org. Chem. 2012, 8, 699–704, doi:10.3762/bjoc.8.78

• effective (Table 1, entries 1 and 2), whereas the binaphthyl-modified, chiral, bifunctional organocatalysts III–VIII, bearing both central and axial chiral elements, effectively promoted the addition reaction in high yield, with high enantioselectivity (78–97% ee, Table 1, entries 3–8). Catalyst III gave

Efficient syntheses of 25,26-dihydrodictyostatin and 25,26-dihydro-6-epi-dictyostatin, two potent new microtubule-stabilizing agents

• María Jiménez,
• Wei Zhu,
• Andreas Vogt,
• Billy W. Day and
• Dennis P. Curran

Beilstein J. Org. Chem. 2011, 7, 1372–1378, doi:10.3762/bjoc.7.161

• amide 10 and alkyl iodide 11 afforded amide 12 in 95% yield. The chiral auxiliary was then removed with BH3·NH3 (92%) [34], then the resulting primary alcohol was oxidized under Swern conditions to provide aldehyde 13 (86%). A Marshall palladium-catalyzed addition reaction [35] between aldehyde 13 and

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

• Lucie Brulikova and
• Jan Hlavac

Beilstein J. Org. Chem. 2011, 7, 678–698, doi:10.3762/bjoc.7.80

• the products 151–154 (Figure 9) were formed as by-products of the palladium catalyzed addition reaction of alkenes to C-5-mercuriated deoxyuridines. The synthesis of derivatives 151 and 152 started with condensation reactions of alkenes 155 and 156 with 5-chloromercuri-2'-deoxyuridine 4 in the

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

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

• reaction mixture in a combined yield of 60%. The major meta product can be converted into the fenestrane by further irradiation (Scheme 18). This second [3 + 2] addition reaction can be accelerated by the addition of sensitizers and could be quenched with piperylene. The proposed mechanism involves a

Michael-type addition of azoles of broad-scale acidity to methyl acrylate

• Sławomir Boncel,
• Kinga Saletra,
• Barbara Hefczyc and
• Krzysztof Z. Walczak

Beilstein J. Org. Chem. 2011, 7, 173–178, doi:10.3762/bjoc.7.24

• and is used as a clinical regulator of the cardiac cycle [5]. Fluconazole (VI) 2-(2,4-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)propan-2-ol is an antifungal drug used in the treatment and prevention of superficial and systemic fungal infections [6]. The base-catalysed Michael-type addition reaction

An easy assembled fluorescent sensor for dicarboxylates and acidic amino acids

• Xiao-bo Zhou,
• Yuk-Wang Yip,
• Wing-Hong Chan and
• Albert W. M. Lee

Beilstein J. Org. Chem. 2011, 7, 75–81, doi:10.3762/bjoc.7.11

• molecular platform via thiourea formation to give the key intermediate 4 in 70% yield. As a result of steric hindrance, an attempt to make the corresponding bis-thiourea adduct from 3 and 9-aminomethylanthracene was unsuccessful. However, 4 underwent a smooth addition reaction with the structurally less

Stereoselective synthesis of four possible isomers of streptopyrrolidine

• Debendra K. Mohapatra,
• Barla Thirupathi,
• Pragna P. Das and
• Jhillu S. Yadav

Beilstein J. Org. Chem. 2011, 7, 34–39, doi:10.3762/bjoc.7.6

• ) SnCl4, (1-ethoxyvinyloxy)trimethylsilane, CH2Cl2, −78 °C, 2 h, 70% (8a:8b = 3:7); (d) LDA, EtOAc, ZnBr2, −78 °C, 1 h, 82%, (8a:8b = 95:5). Reagents and conditions: (a) (1) TFA, CH2Cl2, rt, 4 h; (2) Zr(OtBu)4, HOAt, toluene, 60 °C, 12 h, 82% over two steps. Addition reaction under different conditions to

Formation of epoxide-amine oligo-adducts as OH-functionalized initiators for the ring-opening polymerization of ε-caprolactone

• Julia Theis and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 938–944, doi:10.3762/bjoc.6.105

• , the addition polymerization of primary amines with diepoxides forming linear adducts has been intensively studied [21]. Linear epoxide-amine addition polymers can be obtained for instance by the addition reaction of diglycidyl ethers and aromatic primary amines in equimolar amounts. With regard to our

• reduced to the corresponding amine 3 via catalytic transfer hydrogenation. In presence of 1, a simultaneous addition reaction of the freshly formed amine groups took place (Scheme 1). The reaction was carried out using 4-methyl-1-cyclohexene as a source of hydrogen in bulk. To prevent overheating, the

• successful reduction of the nitroaromatic compound 2 was proven by IR spectroscopy by the disappearance of the asymmetric and symmetric NO2 stretching vibration absorption bands at 1589 and 1329 cm−1, respectively. The addition reaction of the new formed primary aromatic amine 3 with diepoxide 1 was proven

Concise methods for the synthesis of chiral polyoxazolines and their application in asymmetric hydrosilylation

• Wei Jie Li,
• Zun Le Xu and
• Sheng Xiang Qiu

Beilstein J. Org. Chem. 2010, 6, No. 29, doi:10.3762/bjoc.6.29

• catalytic activities and high enantioselectivities in various asymmetric reactions [14][15][16][17][18][19][20]. For example, chiral 1,2,2-tris[2-(4-isopropyloxazolinyl)]propane was shown to lead to high enantioselectivities in the Cu(II)-catalyzed asymmetric Michael addition reaction between indole and

Continuous flow enantioselective arylation of aldehydes with ArZnEt using triarylboroxins as the ultimate source of aryl groups

• Julien Rolland,
• Xacobe C. Cambeiro,
• Carles Rodríguez-Escrich and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2009, 5, No. 56, doi:10.3762/bjoc.5.56

• triethylboroxin mixture in toluene). Both flows were mixed in a T-shaped piece placed immediately before the reactor, in order to minimize the amount of background, non-enantioselective addition reaction before contact with the supported catalyst. Additionally, a supply of dry toluene was connected to both pumps

Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds

• G. K. Surya Prakash,
• Xiaoming Zhao,
• Sujith Chacko,
• Fang Wang,
• Habiba Vaghoo and
• George A. Olah

Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17

• density on the fluorinated carbanion center, which makes the resulting nucleophile softer and more suitable for 1,4-addition with Michael acceptors. Hence, we explored the possibility of a base induced Michael addition reaction. Among the various bases and solvent combinations that we explored, the K2CO3

Flexible synthetic routes to poison- frog alkaloids of the 5,8-disubstituted indolizidine- class I: synthesis of common lactam chiral building blocks and application to the synthesis of (-)-203A, (-)-205A, and (-)-219F

• Naoki Toyooka,
• Dejun Zhou,
• Hideo Nemoto,
• H. Martin Garraffo,
• Thomas F. Spande and
• John W. Daly

Beilstein J. Org. Chem. 2007, 3, No. 29, doi:10.1186/1860-5397-3-29

• Michael-type conjugate addition reaction to a chiral cyclic enamine ester as the key step in constructing the trisubstituted piperidine ring system. To demonstrate the usefulness of these chiral building blocks, syntheses of (-)-203A, (-)-205A from 1, and (-)-219F from 2 have been achieved. Conclusion The

• -disubstituted indolizidine class of poison-frog alkaloids, we designed two lactam chiral building blocks (1, 2). The substituent at the 8-position is stereoselectively created by our original Michael-type conjugate addition reaction. [13][14] Various substituents at the 5-position would be introduced using the

• enoltriflate 5 in good yield. The palladium-catalyzed carbon monoxide insertion reaction [17] in the presence of MeOH afforded the enaminoester 6. The key Michael-type conjugate addition reaction of 6 with lithium dimethylcuprate or divinylcuprate proceeded smoothly to provide the trisubstituted piperidines (7

Pd-catalysed [3 + 3] annelations in the stereoselective synthesis of indolizidines

• Olivier Y. Provoost,
• Andrew J. Hazelwood and
• Joseph P. A. Harrity

Beilstein J. Org. Chem. 2007, 3, No. 8, doi:10.1186/1860-5397-3-8

• compares well with a close analogue reported by Knapp and co-workers suggesting that the aldol addition reaction proceeds under Felkin-Anh control [see Supporting Information File 1]). In conclusion, we have shown that functionalised indolizidinone intermediates can be generated through the Pd-catalysed [3