Structural conditions required for the bridge lithiation and substitution of a basic calix[4]arene

• Conrad Fischer,
• Wilhelm Seichter and
• Edwin Weber

Beilstein J. Org. Chem. 2011, 7, 1602–1608, doi:10.3762/bjoc.7.188

• ], whereas we follow a route involving the formation of a methylene carbanion through lithiation, which by nucleophilic substitution forms the desired bridge-substituted calixarenes [4][5]. While the number of substituted methylene atoms in the first protocol depends clearly on the amount of N

• -bromosuccinimide used, surprisingly only monosubstitution of the chalice is observed by application of the lithiation technique, independent of the amount of n-BuLi. However, twofold substitution on opposite methylene bridges can be achieved by successive application of the latter technique [6]. This may suggest

Total synthesis of (±)-coerulescine and (±)-horsfiline

• Mukund G. Kulkarni,
• Attrimuni P. Dhondge,
• Sanjay W. Chavhan,
• Ajit S. Borhade,
• Yunnus B. Shaikh,
• Deekshaputra R. Birhade,
• Mayur P. Desai and
• Nagorao R. Dhatrak

Beilstein J. Org. Chem. 2010, 6, 876–879, doi:10.3762/bjoc.6.103

• include the following oxidative rearrangements: lead tetraacetate [3], sodium tungstate [11], tert-butyl hypochlorite [12] and N-bromosuccinimide [13]. Other approaches involve the Mannich reaction [14], ring expansion reactions [15][16], 1,3-dipolar [3 + 2] cycloadditions [17][18][19], intramolecular

• 14. Finally, chemoselective reduction of amide 14 with n-BuLi and LAH (under the conditions reported in [27]) gave coerulescine. Compound 1, on treatment with N-bromosuccinimide, gave the 5-bromo derivative, which upon heating with sodium methoxide in the presence of cuprous iodide gave horsfiline in

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

• arylamine. The bromination of aryl units is important for the subsequent palladium-catalyzed coupling reaction. If the aryl unit is thiophene, direct bromination with N-bromosuccinimide is possible to yield monomer M-3 [16]. For the preparation of conjugated DPP-based polymers, palladium-catalyzed

Synthesis of deep- cavity fluorous calix[4]arenes as molecular recognition scaffolds

• Maksim Osipov,
• Qianli Chu,
• Steven J. Geib,
• Dennis P. Curran and
• Stephen G. Weber

Beilstein J. Org. Chem. 2008, 4, No. 36, doi:10.3762/bjoc.4.36

• , particularly palladium catalyzed cross coupling reactions, including Kumada, Negishi, and Suzuki processes which can be used to append aromatic rings onto the molecule [30][31]. Therefore, 3b was treated with N-bromosuccinimide (NBS) in methyl ethyl ketone (MEK) [32] to give the bromide 4 in 87% yield

Dimerization of propargyl and homopropargyl 6-azido- 6-deoxy- glycosides upon 1,3-dipolar cycloaddition

• Nikolas Pietrzik,
• Daniel Schmollinger and
• Thomas Ziegler

Beilstein J. Org. Chem. 2008, 4, No. 30, doi:10.3762/bjoc.4.30

• was deacetylated and treated with N-bromosuccinimide and triphenylphosphine in DMF according to Hanessian's procedure [19] followed by reacetylation of the OH-groups with acetic anhydride in pyridine to afford 2-propynyl 6-bromo-6-deoxy-2,3,4-tri-O-acetyl-β-D-glucopyranoside (3a'') in 60% yield. Next