Synthesis of nanodiamond derivatives carrying amino functions and quantification by a modified Kaiser test

• Gerald Jarre,
• Steffen Heyer,
• Elisabeth Memmel,
• Thomas Meinhardt and
• Anke Krueger

Beilstein J. Org. Chem. 2014, 10, 2729–2737, doi:10.3762/bjoc.10.288

• observed surface loading for 13 is higher due to secondary reactions of already grafted alkoxy silanes [5]. In a first series of experiments the assay was carried out on nanodiamond samples 5 and 15 using the protocol reported by Troll et al. [22]. Surprisingly, very low values for the amino group loading

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• suggested that the alkynyl hydrogen acts as the hydrogen source for the hydrophosphination. This can also explain why the method was not applicable to internal alkynes. Silanes have also been added as the source for hydrogen [241]. Ruthenium complexes are the first catalysts reported for the direct

Synthesis of chiral N-phosphinyl α-imino esters and their application in asymmetric synthesis of α-amino esters by reduction

• Yiwen Xiong,
• Haibo Mei,
• Lingmin Wu,
• Jianlin Han,
• Yi Pan and
• Guigen Li

Beilstein J. Org. Chem. 2014, 10, 653–659, doi:10.3762/bjoc.10.57

• the past years [31][32][33][34][35]. They usually served as mild hydrogen donors, but the use of them also made the purification difficult at the same time. Hydrogen gas is a traditional reduction source [36] and silanes and boranes are also well documented as the choices of reduction reagents [37][38

• used for the asymmetric synthesis of α-amino esters through reduction. The reduction condition scan was firstly focused on the examination of reductants. A number of reductants, including Hantzsch ester, silanes, organoaluminum and boranes were tested in the system. Unfortunately, silanes failed to

Deoxygenative gem-difluoroolefination of carbonyl compounds with (chlorodifluoromethyl)trimethylsilane and triphenylphosphine

• Fei Wang,
• Lingchun Li,
• Chuanfa Ni and
• Jinbo Hu

Beilstein J. Org. Chem. 2014, 10, 344–351, doi:10.3762/bjoc.10.32

• under similar conditions failed to give the gem-difluorinated olefins, which indicate that the halo-substituent of TMSCF2X can influence the reactivity of these fluorinated silanes in difluoromethylene transfer reactions. Further research on the synthetic application of TMSCF2X (X = F, Cl, and Br) is

Synthesis of the B-seco limonoid core scaffold

• Hanna Bruss,
• Hannah Schuster,
• Rémi Martinez,
• Markus Kaiser,
• Andrey P. Antonchick and
• Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

• envisaged to be constructed by 1,2-addition, using the free β-hydroxy functionality in 63 as directing group. Several conditions with allyl boronates, stannanes, silanes, indium, magnesium bromide, cerium, zinc bromide and other reagents have been screened. Finally, the best result was achieved with

Flexible synthesis of anthracycline aglycone mimics via domino carbopalladation reactions

• Markus Leibeling and
• Daniel B. Werz

Beilstein J. Org. Chem. 2013, 9, 2194–2201, doi:10.3762/bjoc.9.258

• . Contrary, benzyl and methoxide-substituted silanes 14c and 14d provided inferior yields. With several domino precursors in hand we started the investigation of the domino-carbopalladation sequence. To our delight, it was possible to adjust the catalytic system that we developed for the synthesis of

• and delivered the desired compounds as major products. Scheme 5 illustrates that all attached substituents at the terminal triple bond were tolerated. Even unsubstituted alkyne 14e and electron-deficient silane 14d furnished the product in high yields. TMS, SiMe2Ph and Si(iPr)2OMe-substituted silanes

• oxidative procedures provided only the mono-oxidized products in trace amounts [40][41][42]. The oxidation of phenyl-substituted silanes to respective phenols is difficult [43][44]. However, literature precedence revealed that benzyl-substituted silane 13c or electron-deficient silane 13d [43][45] should be

Reductions of aldehydes and ketones with a readily available N-heterocyclic carbene borane and acetic acid

• Vladimir Lamm,
• Xiangcheng Pan,
• Tsuyoshi Taniguchi and
• Dennis P. Curran

Beilstein J. Org. Chem. 2013, 9, 675–680, doi:10.3762/bjoc.9.76

• measurement of the nucleophilicity parameter, N [14]. By this measure, NHC-boranes are among the best neutral hydride donors known, more reactive than distant relatives such as silanes, stannanes, and dihydropyridines, and more reactive even than their amine-borane cousins [15][16][17][18][19]. Despite being

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• –Fuchs reaction followed by quenching of the acetylide with cyclohexanone furnishes propargyl silane 136, a compound that is cleanly transformed into allene 137 upon exposure to tetrabutylammonium fluoride [54]. This approach represents perhaps the most versatile route to functional propargyl silanes

Multivalent display of the antimicrobial peptides BP100 and BP143

• Imma Güell,
• Rafael Ferre,
• Kasper K. Sørensen,
• Esther Badosa,
• Iteng Ng-Choi,
• Emilio Montesinos,
• Eduard Bardají,
• Lidia Feliu,
• Knud J. Jensen and
• Marta Planas

Beilstein J. Org. Chem. 2012, 8, 2106–2117, doi:10.3762/bjoc.8.237

• was obtained. It has been previously reported that silanes under acidic conditions can promote the reduction of aldehydes [27]. Cleavage of the peptidyl resins with TFA/H2O (95:5) followed by purification by reversed-phase high-performance liquid chromatography (RP-HPLC) afforded peptide aldehydes 4

Efficient synthesis of 1,3-diaryl-4-halo-1H-pyrazoles from 3-arylsydnones and 2-aryl-1,1-dihalo-1-alkenes

• Yiwen Yang,
• Chunxiang Kuang,
• Hui Jin,
• Qing Yang and
• Zhongkui Zhang

Beilstein J. Org. Chem. 2011, 7, 1656–1662, doi:10.3762/bjoc.7.195

• cycloaddition substrates for pyrazole synthesis [16][17]. These dipolar compounds are readily prepared in two steps from N-functionalized amino acids, and are readily stored and handled. Methods have been disclosed for the [3 + 2] dipolar cycloaddition of sydnones with alkenyl silanes [18] and stannanes [18

• ], alkenyl arenes [19], 1,3-dienes [20][21], α,β-unsaturated esters [19][22] and nitriles [23], phosphane oxides [24] or with alkynyl silanes [18], stannanes [18][25][26], arenes [27][28], esters [29][30][31][32][33], boronic esters [34][35]. However, the cycloaddition of sydnones with 1,1-dihaloalkenes is

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• two compounds: Furanone 35a (40%) and indene 36a (39%) both devoid of a trimethylsilyl group. Since protodesilylation took place readily, it is likely that the allylic silanes 35’e and 36’e were the initially generated products. Their formation could be explained by regioselective electrophilic

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

Ru-catalyzed dehydrogenative coupling of carboxylic acids and silanes - a new method for the preparation of silyl ester

• Guo-Bin Liu and
• Hong-Yun Zhao

Beilstein J. Org. Chem. 2008, 4, No. 27, doi:10.3762/bjoc.4.27

• with silanes. In the presence of 1 mol% Ru3(CO)12 and 4 mol% EtI, dehydrosilylation reactions in toluene afforded the corresponding silyl esters at 100 °C in good and high yields. Keywords: carboxylic acids; ethyl iodide; Ru3(CO)12; silanes; silylation; Introduction Polymers composed of

• chlorination of silanes, either with chlorine gas [7] or with hydrochloric acid under Pd/C catalysis [25][26], the synthesis of silyl esters from the corresponding silanes requires two reaction steps. Some newer synthetic protocols to silyl esters have been developed and a lot of literature focuses itself on

• the transition metal-catalyzed cross-coupling of an active hydrogen-moiety containing substances such as water and alcohols with silanes [27]. There are still few examples of dehydrogenative coupling reaction of carboxylic acids with silanes. Silylating agents such as allyltrimethylsilane

Total synthesis of the indolizidine alkaloid tashiromine

• Stephen P. Marsden and
• Alison D. McElhinney

Beilstein J. Org. Chem. 2008, 4, No. 8, doi:10.1186/1860-5397-4-8

• and their cross-metathesis reactions studied as part of a putative asymmetric approach to tashiromine. In the event, α-hydroxysilane 12 underwent isomerisation under the reaction conditions to acylsilane 17, while silanes 14 and 15 were unreactive towards metathesis. Conclusion A concise

• reactions of chiral α-alkoxysilanes have thus far been unsuccessful. Experimental Experimental protocols for the synthesis of tashiromine 1 and the preparation of silanes 12, 14, 15 and 17 available as Supporting Information File 1. Rationale for stereoselective assembly of the indolizidine core using

Single and double stereoselective fluorination of (E)-allylsilanes

• Marcin Sawicki,
• Angela Kwok,
• Matthew Tredwell and
• Véronique Gouverneur

Beilstein J. Org. Chem. 2007, 3, No. 34, doi:10.1186/1860-5397-3-34

• -enols. The presence of the gem-dimethyl group on the starting silanes 1c and 1d drastically improved the stereochemical outcome of the fluorination. Compounds E-2c and E-2d were formed in 95% and 70% yield respectively, with no trace of Z-isomer detectable in the crude reaction mixture (entries 3 and 4

The use of silicon- based tethers for the Pauson- Khand reaction

• Adrian P. Dobbs,
• Ian J. Miller and
• Saša Martinović

Beilstein J. Org. Chem. 2007, 3, No. 21, doi:10.1186/1860-5397-3-21

• substituents on silicon should either be two isopropyl or two tert-butyl groups in order to achieve reaction. Ditertbutyl silanes were found to be impractical because vinyl- or allylditertbutyl chlorosilanes will not undergo nucleophilic substitution to yield the silyl ethers due to the large steric crowding

• synthesised proving the reaction could be repeated and was not an anomaly. The results for the other silanes did not show the product of the reaction as cyclopentenones. The only identifiable product isolated from any of the other reactions was the silanol associated with hydrolysis of the silicon-oxygen bond

• ethers an alternative methodology had to be applied to both the formation of the silanes and the subsequent formation of the silyl ethers. Simple deprotonation of the alkyne with n-butyllithium and reaction with chlorodiisopropylsilane led to the formation of the desired silanes in good yields. The

Conformational rigidity of silicon- stereogenic silanes in asymmetric catalysis: A comparative study

• Sebastian Rendler and
• Martin Oestreich

Beilstein J. Org. Chem. 2007, 3, No. 9, doi:10.1186/1860-5397-3-9

• Sebastian Rendler Martin Oestreich Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, D-48149 Münster, Germany 10.1186/1860-5397-3-9 Abstract In recent years, cyclic silicon-stereogenic silanes were successfully employed as stereoinducers in transition

• were reported, [6] namely the inter- [7] as well as intramolecular [8] chirality transfers from silicon to carbon. Moreover, we had demonstrated that chiral silanes resolve racemic mixtures of alcohols in a non-enzymatic, transition metal-catalyzed kinetic resolution. [9] During our ongoing

• investigations directed towards the mechanistic elucidation of the origin of the chirality transfer in a palladium-catalyzed hydrosilylation, [10] we had to perform an extensive screening of silicon-stereogenic tertiary silanes. On that occasion, we became aware that a similar level of stereoselection was

Contemporary organosilicon chemistry

• Steve Marsden

Beilstein J. Org. Chem. 2007, 3, No. 4, doi:10.1186/1860-5397-3-4

• -coupling reactions, and the use of silanes as stoichiometric reductants in a range of chemo-, stereo- and enantioselective catalytic reductions. It is therefore a pleasure to serve as Guest Editor for this first "Thematic Series" in the Beilstein Journal of Organic Chemistry, on "Contemporary Organosilicon