Surfactant catalyzed convenient and greener synthesis of tetrahydrobenzo[a]xanthene-11-ones at ambient temperature

• Pravin V. Shinde,
• Amol H. Kategaonkar,
• Bapurao B. Shingate and
• Murlidhar S. Shingare

Beilstein J. Org. Chem. 2011, 7, 53–58, doi:10.3762/bjoc.7.9

• methide (o-QM), subsequent Michael addition of dimedone to the o-QM followed by attack of the phenolic –OH group of the o-QM at the carbonyl carbon of dimedone to yield a cyclic hemiketal that on dehydration affords the final product. To generalize the synthetic procedure, various electronically divergent

Synthesis, spectral characterization, electron microscopic study and thermogravimetric analysis of a phosphorus containing dendrimer with diphenylsilanediol as core unit

• E. Dadapeer,
• B. Hari Babu,
• C. Suresh Reddy and
• Naga Raju Charmarthi

Beilstein J. Org. Chem. 2010, 6, 726–731, doi:10.3762/bjoc.6.85

• with a diphenylsilanediol core was synthesized using a divergent method. Several types of reactions were performed on dendrons of several sizes, either at the level of the core or the surface. The giant Schiff’s base macro molecule possesses 12 imine bonds and 8 hydroxy groups on the terminal phenyl

• on the final dendritic molecule. Keywords: diphenyl silanediol; divergent method; phosphorus containing dendrimer; scanning electron microscopy; Schiff’s base; thermogravimetric analysis; Introduction Dendrimers constitute a new class of macromolecules that can offer a potentially defect-free

• major subdivisions of a dendrimer. Thus, one of the major differences between linear polymers and dendrimers is their branched architecture. They can be constructed by two fundamental approaches namely, the divergent and convergent methods. The divergent method, first reported by Vögtle is based on the

Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

• Dhananjaya Sahoo,
• Susanne Thiele,
• Miriam Schulte,
• Navid Ramezanian and
• Adelheid Godt

Beilstein J. Org. Chem. 2010, 6, No. 57, doi:10.3762/bjoc.6.57

• repeating unit. In the related bidirectional approach two repeating units are added in each coupling step (Scheme 1b) [25]. The divergent-convergent Moore–Tour-route (Scheme 2a) [26][27][28][29] which employs the diethyltriazenyl group to mask an iodo substituent [30][31]. 1-(Diethyltriazenyl)-4-(2

• -trimethylsilylethynyl)benzene is the parent compound. Desilylation and exchange of the triazenyl substituent for an iodo substituent are the two divergent steps followed by the alkynyl–aryl coupling, the convergent step. The dialkyltriazenyl group decomposes during chromatography on silica gel [28]. The divergent

• -hydroxy-1-methylethyl (2-hydroxyprop-2-yl, HOP) [33][34][35][36][37][38]. A rather rarely utilized third divergent-convergent approach (Scheme 2c) [39][40][41] relies on the bromo iodo selectivity of the alkynyl–aryl coupling and bromo iodo exchange via halogen metal exchange. The principles underlying

Anion receptors containing thiazine-1,1-dioxide heterocycles as hydrogen bond donors

• Hong-Bo Wang,
• James A. Wisner and
• Michael C. Jennings

Beilstein J. Org. Chem. 2010, 6, No. 50, doi:10.3762/bjoc.6.50

• , occlude this central cleft like those of 1 and 2. Rather, they form a divergent “V”-shaped geometry upon chelation of anionic species by the two NH groups of 3, regardless of whether coplanarity is maintained with the central benzene ring. The ortho-protons of these terminal rings (Hc) are certainly too

Synthesis of dihydrophenanthridines by a sequence of Ugi-4CR and palladium- catalyzed intramolecular C-H functionalization

• Florence Bonnaterre,
• Michèle Bois-Choussy and
• Jieping Zhu

Beilstein J. Org. Chem. 2008, 4, No. 10, doi:10.3762/bjoc.4.10

• kinetically fast process related to other elementary reactions [28][29][30][31][32][33][34]. These results indicated that by careful choice of reaction conditions, one can easily reach two completely different scaffolds from the same starting material. Such reagent-dependant divergent synthesis of

A divergent asymmetric approach to aza-spiropyran derivative and (1S,8aR)-1-hydroxyindolizidine

• Jian-Feng Zheng,
• Wen Chen,
• Su-Yu Huang,
• Jian-Liang Ye and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2007, 3, No. 41, doi:10.1186/1860-5397-3-41

• drugs for the treatment of cancer. In continuation of a project aimed at the development of enantiomeric malimide-based synthetic methodology, we now report a divergent, concise and highly diastereoselective approach for the asymmetric syntheses of an aza-spiropyran derivative 7 and (1S,8aR)-1

Multiple hydride reduction pathways in isoflavonoids

• Auli K. Salakka,
• Tuija H. Jokela and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2006, 2, No. 16, doi:10.1186/1860-5397-2-16

• ). We have discussed a possible mechanism to explain these hydroxyl-dependent divergent pathways [43]. To summarize, all hydride addition reactions with isoflavones appear to involve an initial 1,4-addition to give the isoflavanone enolate. In a hydroxylic solvent, or even on workup under basic

Investigation of acetyl migrations in furanosides

• O. P. Chevallier and
• M. E. Migaud

Beilstein J. Org. Chem. 2006, 2, No. 14, doi:10.1186/1860-5397-2-14

• these compounds were treated under neutral or mildly basic/acidic reaction conditions that promote the unmasking of a silylated alcohol. Results and discussion All acetylated furanosides were prepared according to synthetic routes which favoured divergent syntheses (see additional information for full