Straightforward synthesis of a tetrasaccharide repeating unit corresponding to the O-antigen of Escherichia coli O16

• Manas Jana and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 1757–1762, doi:10.3762/bjoc.9.203

• transfer hydrogenation with triethylsilane and 10% Pd/C [20]; (b) an acetylation using acetic anhydride and pyridine, and (c) a saponification reaction with sodium methoxide to furnish compound 1, which was purified over a Sephadex® LH-20 gel to give the pure compound 1 in 64% overall yield. The structure

Appel-reagent-mediated transformation of glycosyl hemiacetal derivatives into thioglycosides and glycosyl thiols

• Tamashree Ghosh,
• Abhishek Santra and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 974–982, doi:10.3762/bjoc.9.112

• agents (triphenylphosphine or combination of triethylsilane and BF3·OEt2) followed by the reaction of the in situ generated thiolate ions with glycosyl bromides under phase-transfer conditions [23] or in ionic liquids [24]; (b) reaction of glycosyl bromides with thiols under phase-transfer conditions [25

Short synthesis of the common trisaccharide core of kankanose and kankanoside isolated from Cistanche tubulosa

• Goutam Guchhait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 705–709, doi:10.3762/bjoc.9.80

• = 7.5 Hz, H-1A in the 1H NMR and at δ 101.9 (PhCH), 101.3 (C-1A), 97.4 (C-1B) in the 13C NMR spectra]. Removal of the benzylidene acetal group under neutral conditions by using triethylsilane and Pd/C [15] resulted in the formation of disaccharide diol 7 in 80% yield. NOBF4 catalyzed regio- and

Removal of benzylidene acetal and benzyl ether in carbohydrate derivatives using triethylsilane and Pd/C

• Abhishek Santra,
• Tamashree Ghosh and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 74–78, doi:10.3762/bjoc.9.9

• achieved under catalytic transfer hydrogenation conditions by using a combination of triethylsilane and 10% Pd/C in CH3OH at room temperature. A variety of carbohydrate diol derivatives were prepared from their benzylidene derivatives in excellent yield. Keywords: benzylidene; glycoside; Pd/C; transfer

• hydrogenation; triethylsilane; Introduction Functionalization of carbohydrate intermediates is essential for their assembly towards the synthesis of complex oligosaccharides [1][2][3][4][5][6][7][8][9]. Benzylidene acetal is a frequently used protecting group for the simultaneous protection of 1,2- and 1,3

• [22] of triethylsilane (Et3SiH) and 10% Pd/C. In our synthetic endeavor we sought to explore the catalytic potential of a combination of Et3SiH and 10% Pd/C in the deprotection of a benzylidene group in the carbohydrate derivatives, without the formation of unwanted byproducts. We report herein our

S-Fluorenylmethyl protection of the cysteine side chain upon N^α-Fmoc deprotection

• Johannes W. Wehner and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2012, 8, 2149–2155, doi:10.3762/bjoc.8.242

• mannopyranside 4 can be prepared by Staudinger ligation of O-acetyl-protected 2-azidoethyl α-D-mannopyranoside [11] and the cysteine derivative Fmoc-Cys(Trt)-OH as described earlier [1]. Then, a sequence of Fmoc-deprotection, leading to 5 and acidic removal of the trityl group by using TFA and triethylsilane

• according to the literature [3]. N-(Fluoren-9-ylmethoxycarbonyl)-L-cysteine-[2-(2,3,4,6-tetra-O-acetyl-α-D-mannopyranosyloxy)ethyl]amide (7) The S-protected glycoamino acid derivative 4 (1.35 g, 1.41 mmol) was dissolved in dry dichloromethane (8 mL), and then triethylsilane (1.26 mL, 7.91 mmol) and TFA (600

Convergent synthesis of the tetrasaccharide repeating unit of the cell wall lipopolysaccharide of Escherichia coli O40

• Abhijit Sau and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2012, 8, 2053–2059, doi:10.3762/bjoc.8.230

• ) exploitation of the armed–disarmed glycosylation concept for the orthogonal activation of thioglycoside during the synthesis of disaccharide derivative 9 [19]; (d) use of aminoethyl linker as the anomeric protecting group; (e) removal of benzyl groups using a combination of triethylsilane and Pd(OH)2–C [20

• -benzylidene acetal with triethylsilane and iodine [22] furnished compound 6 in 82% yield. Stereoselective glycosylation of compound 6 with thioglycoside derivative 3 in the presence of a combination of N-iodosuccinimide (NIS) and HClO4–SiO2 [17] gave disaccharide derivative 7 in a 77% yield. Formation of

• isopropylidene ketal and benzylidene acetal by acid hydrolysis; and finally (d) removal of benzyl ethers by using triethylsilane and 20% Pd(OH)2–C [20] to furnish target compound 1, which was purified through a Sephadex® LH-20 column to give pure compound 1 in 60% overall yield. Spectral data of compound 1

Translation of microwave methodology to continuous flow for the efficient synthesis of diaryl ethers via a base-mediated S_NAr reaction

• Charlotte Wiles and
• Paul Watts

Beilstein J. Org. Chem. 2011, 7, 1360–1371, doi:10.3762/bjoc.7.160

• ], fluoride mediated couplings [10][11], and the use of solid supports [12]. Until recently, the nucleophilic substitution of aromatic halides to phenolic substrates has been largely overlooked, with Ueno and coworkers [13] reporting the use of triethylsilane and a phosphazene “super base”, Holmes [14

Convergent synthesis of the tetrasaccharide repeating unit of the O-antigen of Shigella boydii type 9

• Abhishek Santra and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2011, 7, 1182–1188, doi:10.3762/bjoc.7.137

• recently developed environmentally benign reaction conditions for protecting group manipulations and glycosylations such as, (i) O-acetylation using sulfamic acid [20], (ii) regioselective ring opening of the benzylidene acetal using a combination of triethylsilane and iodine [21], (iii) direct one-pot

• acetylation using acetic anhydride in the presence of sulfamic acid [20] followed by regioselective reductive ring opening of the benzylidene acetal using a combination of triethylsilane and iodine [21] to furnish 4-methoxyphenyl (2,3-di-O-acetyl-6-O-benzyl-α-D-glucopyranosyl)-(1→4)-2,3,6-tri-O-acetyl-β-D

• removed under reduced pressure and the crude reaction mixture was passed through a short pad of silica gel using hexane–EtOAc (1:2) as eluant to give pure acetylated product (3.8 g, 91%). To a solution of the acetylated product (3.5 g, 4.69 mmol) in CH3CN (15 mL) triethylsilane (1.5 mL, 9.39 mmol) and

Synthesis of 5-(2-methoxy-1-naphthyl)- and 5-[2-(methoxymethyl)-1-naphthyl]-11H-benzo[b]fluorene as 2,2'-disubstituted 1,1'-binaphthyls via benzannulated enyne–allenes

• Yu-Hsuan Wang,
• Joshua F. Bailey,
• Jeffrey L. Petersen and
• Kung K. Wang

Beilstein J. Org. Chem. 2011, 7, 496–502, doi:10.3762/bjoc.7.58

• 6a (Scheme 3). Condensation between 6a and pivalophenone (7) then furnished the benzannulated enediynyl alcohol 8a. Subsequent reduction with triethylsilane in the presence of trifluoroacetic acid afforded the benzannulated enediyne 9a. Similarly, the benzannulated enediyne 9b was synthesized from 1

• nitrogen atmosphere. Diethyl ether and tetrahydrofuran (THF) were distilled from benzophenone ketyl prior to use. 1-Ethynyl-2-methoxybenzene (4a), pivalophenone (7), n-butyllithium (1.6 M) in hexanes, 1-bromo-2-[2-(trimethylsilyl)ethynyl]benzene, triethylsilane, trifluoroacetic acid, potassium tert

• over sodium sulfate, and concentrated. The residue was purified by flash chromatography (silica gel/10% diethyl ether in hexanes) to afford 1.476 g of crude 16 as a light yellow liquid. Crude 16 without any further purification was treated with 0.810 g of triethylsilane (6.983 mmol) and 2.1 g of

EPR and pulsed ENDOR study of intermediates from reactions of aromatic azides with group 13 metal trichlorides

• Giorgio Bencivenni,
• Riccardo Cesari,
• Daniele Nanni,
• Hassane El Mkami and
• John C. Walton

Beilstein J. Org. Chem. 2010, 6, 713–725, doi:10.3762/bjoc.6.84

• anhydrous indium trichloride (243 mg, 1.1 mmol, previously dried by heating at 130 °C under argon for 1 h) and triethylsilane (177 μL, 1.1 mmol) in ACN (4 mL) for 5 min at 0 °C [47]. The resulting solution was rapidly transferred into a quartz capillary tube and nitrogen was bubbled inside for few minutes

Diastereoselective functionalisation of benzo-annulated bicyclic sultams: Application for the synthesis of cis-2,4-diarylpyrrolidines

• Susan Kelleher,
• Pierre-Yves Quesne and
• Paul Evans

Beilstein J. Org. Chem. 2009, 5, No. 69, doi:10.3762/bjoc.5.69

• [16][17]. Unfortunately, however, under a variety of conditions it proved impossible to elaborate these species. For example, reductive ring-opening using triethylsilane, conditions previously reported for N-sulfonylamino-α,β-epoxides [18][19], led only to recovery of starting material and not the

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• directly the mitosene 111 (Scheme 31). As expected, in this case, the lithium-metal exchange occurred much faster and inverted the ratio of tetracyclic:tricyclic product from 1:10 to 4:1. Removal of the trityl protecting group was then achieved using triethylsilane and methanesulfonic acid to give the

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

• triethylsilane was employed as a model to optimize the reaction conditions. The dehydrogenative coupling was found to be finished after 8 h at 100 °C, in the presence of 1 mol% Ru3(CO)12 and 4 mol% EtI in toluene, giving the corresponding triethylsilyl propionate in 95% yield (Table 1, Run 3). When the amount of

• 100 °C (Table 3, Run 3). Treatment of a number of carboxylic acids and silanes such as triethylsilane, tri-n-propylsilane (n-Pr3SiH), tri-iso-propylsilane (iso-Pr3SiH), tri-n-butylsilane (n-Bu3SiH) or tert-butyldimethylsilane (tert-BuMe2SiH) afforded the corresponding silyl esters in good and

• method. We are currently broadening the scope of this dehydrosilylation of carboxylic acids and silanes in our laboratory and the results will be published elsewhere. Experimental To a mixture of propionic acid (40 mmol, 2.96 g), and triethylsilane (40 mmol, 4.64 g) in toluene (20 ml) was added Ru3(CO)12

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

• derivatives using standard conditions ((Boc)2O (4 equiv), THF, DMAP) to give 13 in 90% yield as a crystalline solid. N-Boc lactam 13 was then reduced to lactol 14 with DIBAL-H to afford a mixture of diastereomers in 86% yield, which was reduced with triethylsilane in the presence of BF3·OEt2 to give carbamate

Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives

• Andrew Kennedy,
• Adam Nelson and
• Alexis Perry

Beilstein J. Org. Chem. 2005, 1, No. 2, doi:10.1186/1860-5397-1-2

• .) For the syntheses of the allylated and reduced substrates, the crude products were treated directly with boron trifluoride etherate and either allyltrimethylsilane or triethylsilane. It was possible to switch cleanly to a one-directional synthesis because the N,O acetals were much more susceptible to