Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• degradations, dual-channel reactors have been used for synthetically useful transformations. Returning to the oxidation of α-terpinene, moderate yields of ascaridole were obtained by using a silica-supported fullerene promoter [38]. Similarly, L-methionine was efficiently oxidised to the corresponding

Synthesis and ring openings of cinnamate-derived N-unfunctionalised aziridines

• Alan Armstrong and
• Alexandra Ferguson

Beilstein J. Org. Chem. 2012, 8, 1747–1752, doi:10.3762/bjoc.8.199

• carbonyl compounds. Our method produces trans-NH-aziridines from α,β-unsaturated carbonyl compounds in good to excellent yield with high diastereoselectivity (Figure 1) [21]. An N–N ylide (aminimine) is the presumed active intermediate, formed from the reaction of a tertiary amine promoter and an aminating

Antifreeze glycopeptide diastereomers

• Lilly Nagel,
• Carsten Budke,
• Axel Dreyer,
• Thomas Koop and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 1657–1667, doi:10.3762/bjoc.8.190

• silver salt promoter AgClO4 (0.25 equiv) was added at room temperature and stirring was continued for 30 min. Subsequently, the 2-azido-2-deoxy-3,4,6-tri-O-acetyl-α-D-galactopyranosyl chloride (1.5 equiv) was added dissolved in abs toluene (30–40 mL) and methylene chloride (30–40 mL), and the solution

Extending the utility of [Pd(NHC)(cinnamyl)Cl] precatalysts: Direct arylation of heterocycles

• Anthony R. Martin,
• Anthony Chartoire,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2012, 8, 1637–1643, doi:10.3762/bjoc.8.187

• investigated. Among four different precatalysts, [Pd(SIPr)(cinnamyl)Cl] proved to be the most efficient promoter of the reaction. The C–H functionalization of sulfur- or nitrogen-containing heterocycles has been achieved at low catalyst loadings. These catalyst charges range from 0.1 to 0.01 mol % palladium

Automated synthesis of sialylated oligosaccharides

• Davide Esposito,
• Mattan Hurevich,
• Bastien Castagner,
• Cheng-Chung Wang and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 1601–1609, doi:10.3762/bjoc.8.183

• was the glycosylation of compound 14 with building block 4 (Scheme 2), which proceeded efficiently in the presence of trimethylsilyl triflate (TMSOTf) as promoter at −10 °C to afford trisaccharide 15 with a yield of 80%. It is worth mentioning that glycosylation of an analogue of glucose 14 equipped

Recyclable fluorous cinchona alkaloid ester as a chiral promoter for asymmetric fluorination of β-ketoesters

• Wen-Bin Yi,
• Xin Huang,
• Zijuan Zhang,
• Dian-Rong Zhu,
• Chun Cai and
• Wei Zhang

Beilstein J. Org. Chem. 2012, 8, 1233–1240, doi:10.3762/bjoc.8.138

• , Boston, MA 02125, USA 10.3762/bjoc.8.138 Abstract A fluorous cinchona alkaloid ester has been developed as a chiral promoter for the asymmetric fluorination of β-ketoesters. It has comparable reactivity and selectivity to the nonfluorous versions of cinchona alkaloids and can be easily recovered from

• the reaction mixture by simple fluorous solid-phase extraction (F-SPE) and used for the next round of reaction without further purification. Keywords: asymmetric fluorination; β-ketoester; fluorous cinchona ester; organocatalysis; recyclable chiral promoter; Introduction Fluorinated organic

• was also found that lowering of the reaction temperature from 25 to 10 or 0 °C did not necessarily improve the enantioselectivity of the fluorination (Table 1, entries 16 and 17). Recycling of promoter C-1 is an important part of this project. In our previous work we have demonstrated that fluorous

An easy α-glycosylation methodology for the synthesis and stereochemistry of mycoplasma α-glycolipid antigens

• Yoshihiro Nishida,
• Yuko Shingu,
• Yuan Mengfei,
• Kazuo Fukuda,
• Hirofumi Dohi,
• Sachie Matsuda and
• Kazuhiro Matsuda

Beilstein J. Org. Chem. 2012, 8, 629–639, doi:10.3762/bjoc.8.70

• phosphocholine group at the sugar 6-OH position, we employed a phosphoroamidite method using 1H-tetrazole as a promoter [34]. First, 8a was treated with 2-cyanoethyl-N,N,N’,N’-tetraisopropyl phosphorodiamidite in the presence of 1H-tetrazole, and then with choline tosylate to give 9a. After removal of the sugar

2-Allylphenyl glycosides as complementary building blocks for oligosaccharide and glycoconjugate synthesis

• Hemali D. Premathilake and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2012, 8, 597–605, doi:10.3762/bjoc.8.66

• trend, namely no reaction with TMSOTf and smooth glycosylation with MeOTf [32]. NIS/TMSOTf is a powerful promoter for the activation of both O-pentenyl and thioglycosides. It was also found to be effective for the activation of AP glycosyl donor 1a, upon which disaccharide 6a was obtained in 80% yield

• . Even faster reaction and higher yield was obtained by using the NIS/TfOH promoter system, wherein the resulting disaccharide 6a was obtained in 90% yield (Table 1, entry 4). The latter reaction conditions were chosen for use in the investigation of the glycosylation of the secondary glycosyl acceptors

Mutational analysis of a phenazine biosynthetic gene cluster in Streptomyces anulatus 9663

• Orwah Saleh,
• Katrin Flinspach,
• Lucia Westrich,
• Andreas Kulik,
• Bertolt Gust,
• Hans-Peter Fiedler and
• Lutz Heide

Beilstein J. Org. Chem. 2012, 8, 501–513, doi:10.3762/bjoc.8.57

• ]; PemK binds to the promoter region of the Pem operon in E. coli. Finally, orf4 (2613 bp) showed homology to aminopeptidases. λ-RED recombination was used to delete the entire coding sequence of orf1 and the first 437 nucleotides of orf2 from the insert of cosmid ppzOS04 (Figure 1). After recombination

• alternative hypotheses may explain this observation: The regulatory gene orf3 may be involved in the regulation of the prenylation; or the deletion of the entire orf4 sequence may have affected the promoter of the prenyltransferase gene ppzP, which is situated downstream of orf4. In order to distinguish

• between these two possibilities, an additional λ-RED-mediated gene inactivation was carried out (Figure 1). The genes orf1, orf2, orf3 and the first 1092 bp of orf4 were deleted, resulting in cosmid ppzOS22. In this construct, the regulator orf3 is deleted, but the promoter region of ppzP is expected to

Syntheses and applications of furanyl-functionalised 2,2’:6’,2’’-terpyridines

• Jérôme Husson and
• Michael Knorr

Beilstein J. Org. Chem. 2012, 8, 379–389, doi:10.3762/bjoc.8.41

• [19][21] was tested, since it is known to be an efficient promoter of aldol condensations and Michael additions under solvent-free conditions [22][23]. Nevertheless, the treatment of furanyl-substituted aldehydes 1, 3 and 15 did not yield the targeted diketo-intermediates, but instead the chalcones 5

Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium–arene complexes

• Yannick Borguet,
• Xavier Sauvage,
• Guillermo Zaragoza,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2010, 6, 1167–1173, doi:10.3762/bjoc.6.133

• the Ru(II)–Ru(III) mixed-valence compound [(p-cymene)Ru(μ-Cl)3RuCl2(PCy3)], which was found to be an efficient promoter for atom transfer radical reactions under the adopted experimental conditions. Keywords: Grubbs catalyst; indenylidene ligands; Kharasch reaction; microwave heating; olefin

• metathesis; Introduction During the course of our investigations on homobimetallic ruthenium–arene complexes, we found that the indenylidene compound [(p-cymene)Ru(μ-Cl)3RuCl(3-phenyl-1-indenylidene)(PCy3)] (1) was a very efficient promoter for the ring-closing metathesis (RCM) of diethyl 2,2

• 1 into mixed-valence bimetallic scaffold 7. This well-defined compound was an efficient promoter for the ATRC of intermediate 5 into the final product 6. Reaction of homobimetallic ruthenium–indenylidene complex 1 with ethylene. Schematic illustration of tandem assisted catalysis with complexes 1

Synthesis of 6-PEtN-α-D-GalpNAc-(1–>6)-β-D-Galp-(1–>4)-β-D-GlcpNAc-(1–>3)-β-D-Galp-(1–>4)-β-D-Glcp, a Haemophilus influenzae lipopolysacharide structure, and biotin and protein conjugates thereof

• Andreas Sundgren,
• Martina Lahmann and
• Stefan Oscarson

Beilstein J. Org. Chem. 2010, 6, 704–708, doi:10.3762/bjoc.6.80

• -containing lactose derivative a suitably protected lacto-N-neotetraose tetrasaccharide structure was constructed through subsequential couplings with two thioglycoside donors, a glucosamine residue followed by a galactose derivative, using NIS/AgOTf as promoter. Removal of a silyl protecting group at the

• are often used as acceptors for regioselective glycosidations in the 3-position. However, the selectivity is dependent on the donor, promoter and conditions employed [15], e.g., it has been shown that donors containing a 4,6-O-benzylidene acetal can give a mixture of products [16]. Hence, the diol 7

Synthesis, electronic properties and self-assembly on Au{111} of thiolated (oligo)phenothiazines

• Adam W. Franz,
• Svetlana Stoycheva,
• Michael Himmelhaus and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2010, 6, No. 72, doi:10.3762/bjoc.6.72

• thiols on Au{111}. The ability of the molecules to form SAMs was investigated by solution adsorption of different systems onto gold films of 100 nm thickness thermally evaporated onto Si wafers using 10 nm of Ti as adhesion promoter. This procedure is known to yield polycrystalline gold films with

Vinylogous Mukaiyama aldol reactions with 4-oxy-2-trimethylsilyloxypyrroles: relevance to castanospermine synthesis

• Roger Hunter,
• Sophie C. M. Rees-Jones and
• Hong Su

Beilstein J. Org. Chem. 2007, 3, No. 38, doi:10.1186/1860-5397-3-38

• appropriate amine (PMBNH2 or BnNH2 respectively) with ethyl E-4-chloro-3-methoxybut-2-enoate.[11] Reaction of 4b with n-BuLi as before followed by TMSCl to generate 5b, and reaction with aldehyde 7 (0.7 equiv) as limiting reagent using SnCl4 (2 equiv) as the Lewis-acid promoter with rapid stirring of the

• would have presented steric hindrance at nitrogen towards the Lewis-acid. We have also previously reported on the use of 4-methoxy-2-trimethylsilyloxypyrroles for generating C-5 quaternary centres using trimethyl orthoformate as the electrophile and BF3·OEt2 as the promoter.[10] Together with the

The first organocatalytic carbonyl- ene reaction: isomerisation- free C-C bond formations catalysed by H-bonding thio- ureas

• Matthew L. Clarke,
• Charlotte E. S. Jones and
• Marcia B. France

Beilstein J. Org. Chem. 2007, 3, No. 24, doi:10.1186/1860-5397-3-24

• was carried out (Scheme 2 and Table 1). N,N'-di [3,5-bis(trifluoromethyl)phenyl]thiourea 5,[18], emerged as by far the most active promoter for this reaction. The catalyst was used at 20 mol % loading and compared against a control reaction with no catalyst. Products were isolated by chromatography

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

• (Scheme 3).[10][11] Finally, in a recent report, Porter has described the intramolecular Pauson-Khand reaction of allyldimethyl- and allyldiphenylsilyl propargyl ethers promoted by dicobalt octacarbonyl and n-butyl methyl sulphide as a promoter to give the bicycles in modest to good yields (Scheme 4).[12

• each compound were first prepared and characterised, prior to addition of the promoter. Unfortunately, none of the promoters gave any of the desired products but simply de-complexed starting materials were recovered in each case. Alternative metal carbonyls were also investigated, with compounds 1–4

Asymmetric aza-Diels- Alder reaction of Danishefsky's diene with imines in a chiral reaction medium

• Bruce Pégot,
• Olivier Nguyen Van Buu,
• Didier Gori and
• Giang Vo-Thanh

Beilstein J. Org. Chem. 2006, 2, No. 18, doi:10.1186/1860-5397-2-18

• )-(-)-methylbenzylamine chiral auxiliary. However, all reactions had to be performed in an organic solvent under an inert atmosphere and required stoichiometric loadings of Lewis acid promoter, the use of which is not recommended under 'green chemistry' conditions. Having established the high efficiency of chiral ILs is

Colchitaxel, a coupled compound made from microtubule inhibitors colchicine and paclitaxel

• Karunananda Bombuwala,
• Thomas Kinstle,
• Vladimir Popik,
• Sonal O. Uppal,
• James B. Olesen,
• Jose Viña and
• Carol A. Heckman

Beilstein J. Org. Chem. 2006, 2, No. 13, doi:10.1186/1860-5397-2-13

• transiently by promoter treatment [58]. The phenotype induced by the microtubule inhibitor combination is qualitatively similar to that of promoter-treated cells but differs in direction. Therefore, reversal of cancer cell phenotype suggested that the same downstream mechanisms, i.e. the activation or