Synthesis and antifungal properties of papulacandin derivatives

• Marjolein van der Kaaden,
• Eefjan Breukink and
• Roland J. Pieters

Beilstein J. Org. Chem. 2012, 8, 732–737, doi:10.3762/bjoc.8.82

• synthesis started with the saponification of 15, followed by the protection of O-4 and O-6 by using di-tert-butylsilyl bis(trifluoromethanesulfonate). Subsequent protection of O-3 with TES-Cl, gave the fully protected glucal 18. According to Denmark et al. [31], lithiation and silylation of 18 should give

Cyanoethylation of the glucans dextran and pullulan: Substitution pattern and formation of nanostructures and entrapment of magnetic nanoparticles

• Kathrin Fiege,
• Heinrich Lünsdorf,
• Sevil Atarijabarzadeh and
• Petra Mischnick

Beilstein J. Org. Chem. 2012, 8, 551–566, doi:10.3762/bjoc.8.63

• of iron oxide nanoparticles, various portions were mixed with the cyanoethylpolysaccharides before dialysis. Polysaccharide structures of pullulan and dextran cyanoethylation with acrylonitrile and NaOH as catalyst; sample preparation for GLC/GLC–MS analysis: depolymerization and silylation. ATR–IR

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

• quantitatively. 3.1.4 Silyl derivatives: In 1996, Hampton investigated the selectivity of silylation on oxacalix[3]arenes to determine the influence of the group in the para-position, the nature of the silylating agent and the reaction conditions [41]. Unsurprisingly, the formation of the partial-cone was

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

• starting from commercially available pseudoephedrine amide 10. The syntheses of the bottom fragments 6a and 6b were achieved by applying the previously reported cross-metathesis reactions of readily available 20a,b with (2Z,4E)-methyl hexa-2,4-dienoate followed by silylation to provide 21a,b [39]. These

Amine-linked diglycosides: Synthesis facilitated by the enhanced reactivity of allylic electrophiles, and glycosidase inhibition assays

• Ian Cumpstey,
• Jens Frigell,
• Elias Pershagen,
• Tashfeen Akhtar,
• Elena Moreno-Clavijo,
• Inmaculada Robina,
• Dominic S. Alonzi and
• Terry D. Butters

Beilstein J. Org. Chem. 2011, 7, 1115–1123, doi:10.3762/bjoc.7.128

• unsaturated glycoside 4 to be achieved; phosphomolybdic acid [32] gave the product (α:β, 8:1) in 63% yield. Deacetylation of 4 and regioselective silylation of the primary alcohol gave the threo allylic alcohol 2. The sulfonamide nucleophiles 6, 7 and 9 were prepared from the corresponding amines 5 [33] and 8

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

• protected by the silylation with hexamethyldisilazane. Subsequently, this modified uracil was reacted with protected 2-deoxyribose in the presence of SnCl4. Finally, protected α- and β-anomers 111 and 109 were treated with methanolic sodium methoxide to afford the nucleosides 112 and 110. Synthesis of

Synthesis of glycoconjugate fragments of mycobacterial phosphatidylinositol mannosides and lipomannan

• Benjamin Cao,
• Jonathan M. White and
• Spencer J. Williams

Beilstein J. Org. Chem. 2011, 7, 369–377, doi:10.3762/bjoc.7.47

• Glycosidation of 8-azidooctan-1-ol (Supporting Information File 2) using glycosyl bromide 11 [36] in the presence of AgOTf, and debenzoylation of the crude product gave 12 in 81% yield over 2 steps (Scheme 2). Regioselective silylation of the primary alcohol of 12 with TPSCl followed by benzoylation of the

Chiral recognition of macromolecules with cyclodextrins: pH- and thermosensitive copolymers from N-isopropylacrylamide and N-acryloyl-D/L-phenylalanine and their inclusion complexes with cyclodextrins

• Sabrina Gingter,
• Ella Bezdushna and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 204–209, doi:10.3762/bjoc.7.27

• conditions (Scheme 1). The molar weight distribution of polymers 3D and 3L were determined by gel permeation chromatography (GPC) after silylation of the free carboxylic groups with trimethylchlorosilane. The resulting copolymer 3D, 3L (1:20) is soluble in water below the critical solution temperature (LCST

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

• designed and synthesised (Scheme 1). Reductive ring opening, with BH3/Bu2BOTf [12], of the benzylidene acetal in the known ethyl thioglycoside 1 [13] gave the 6-hydroxy derivative 2 (85%), which was then silylated to afford donor 3 (90%). Regioselective silylation of the 2-azido-galactose ethyl

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• stannane 205 (Scheme 28) [82]. Addition of the latter to the former in the presence of InCl3 afforded the anti adduct 213 which was protected as the SEM ether 214. Hydrogenation followed by OTBS cleavage with TBAF and selective silylation of the primary alcohol with TBSCl and Et3N-DMAP led to the secondary

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• silylation / cycloaddition conditions that had successfully advanced 94 to 95, and it was recovered unchanged after many such attempts. Thus, extensive studies were performed to find suitable conditions for the silylation reaction. Silyl enol ether formation failed to occur under Corey-Gross (LDA, R3SiCl

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

• in the presence of other functional groups carrying different protecting groups. Indeed, silylation of carboxylic acids is a useful method for their protection because deprotection of silyl esters is easily achieved under mild reaction conditions [15][16][17][18]. Generally, silyl esters are made by

Solvent- controlled regioselective protection of allyl- 4,6-benzylidene glucopyranosides

• Kerry Ann Ness and
• Marie E. Migaud

Beilstein J. Org. Chem. 2007, 3, No. 26, doi:10.1186/1860-5397-3-26

• silylation at the 2-position of allyl 4,6-O-benzylidene α-D-glucopyranoside in high yields and which does not require the use of catalysts. Background Numerous syntheses of oligosaccharides incorporating glucose moieties have been reported. In most cases, a limiting synthetic factor is the number of

• . Alkylation, acylation and silylation using halogenated reagents offered mono-protection when reactions were carried out in THF and regio-selectivity was achieved when large protecting groups were employed (Table 1) (see Supporting Information File 1 for full experimental data). In most cases, the expected

• regioselectivity, alkylation and silylation reactions of other 4,6-benzylidene protected glycosides were carried out (Table 2, Table 3, Table 4). The reaction carried out with DMF as solvent gave the bis-protected galactosides when PMBCl was used and no reaction when the silylating reagents were used. In THF

Reaction of benzoxasilocines with aromatic aldehydes: Synthesis of homopterocarpans

• Míriam Álvarez-Corral,
• Cristóbal López-Sánchez,
• Leticia Jiménez-González,
• Antonio Rosales,
• Manuel Muñoz-Dorado and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2007, 3, No. 5, doi:10.1186/1860-5397-3-5

• Starting materials The starting material required for this synthesis is the novel heterocycle 3,6-dihydro-2,2-dimethyl-2H-benzo [g][1,2]oxasilocine (5), which can be prepared through ring closing metathesis (RCM), as has been previously reported for the non-benzofused system. [17][18][19] Thus, silylation

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

• experimental data). Riboside 1 was synthesised from ribose in 47% overall yield via a chemoselective silylation of the C-5 primary hydroxyl group of 2,3-O-isopropylidene ribose (Scheme 2). The acetylated xyloside 2 and riboside 3 were both synthesised from xylose in 46% and 45% overall yield, respectively. The

Synthesis of 2,6-trans- disubstituted 5,6-dihydropyrans from (Z)-1,5-syn-endiols

• Eric M. Flamme and
• William R. Roush

Beilstein J. Org. Chem. 2005, 1, No. 7, doi:10.1186/1860-5397-1-7

• silylation of the allylic alcohol unit followed by mesylate formation and base-promoted nucleophilic displacement. Findings We recently reported a one-pot double allylboration reaction sequence which provides (Z)-1,5-syn-endiols from simple aldehyde starting materials with excellent diastereo- and

• silylated preferentially. The homoallylic TBS ethers 12 and the bis-TBS ethers 13 can be conveniently recycled. The origin of the regioselectivity of the selective silylation of 1,5-diols 2 is unknown at present. Subsequent treatment of mono-TBS ethers 9 with methanesulfonyl chloride (MsCl) followed by

• temperatures. However, a much more general procedure for synthesis of the enantiomeric dihydropyrans ent-3 involves the stannyl ether mediated cyclization of hydroxy mesylates 11. This method relies on a selective silylation of the homoallylic alcohol, and represents a new route to access 2,6-trans

Synthesis of highly substituted allenylsilanes by alkylidenation of silylketenes

• Stephen P. Marsden and
• Pascal C. Ducept

Beilstein J. Org. Chem. 2005, 1, No. 5, doi:10.1186/1860-5397-1-5

• our previously reported conditions for rhodium(II) octanoate-mediated rearrangement of silyl diazoketones 2,[23] which in turn were prepared by C-silylation of the parent diazoketones 3 with triethylsilyl triflate,[28] Scheme 1, Table 1. It should be noted that while the alkyl-substituted silylketenes