Synthesis and structure of tricarbonyl(η⁶-arene)chromium complexes of phenyl and benzyl D-glycopyranosides

• Thomas Ziegler and
• Ulrich Heber

Beilstein J. Org. Chem. 2012, 8, 1059–1070, doi:10.3762/bjoc.8.118

• Thomas Ziegler Ulrich Heber Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076 Tuebingen, Germany 10.3762/bjoc.8.118 Abstract A series of 15 glycoside-derived tricarbonyl(η6-arene)chromium complexes were prepared in 19–87% yield by heating fully acetylated or

• hydrogen bonds. Keywords: aryl glycosides; carbohydrates; transition-metal complex; tricarbonyl(arene)chromium; Introduction In 1957, Fischer and Öfele published the preparation of tricarbonyl(η6-benzene)chromium, which was the first arene tricarbonylchromium complex [1]. Since then, a plethora of

• transition-metal complexes of arenes have been prepared, characterized and described in the literature. Among the multitude of transition-metal complexes of aromatic compounds, however, only tricarbonyl(η6-arene)chromium compounds are widely used for organic syntheses [2][3][4]. This is due to the fact that

Synthesis and oxidation of some azole-containing thioethers

• Andrei S. Potapov,
• Nina P. Chernova,
• Vladimir D. Ogorodnikov,
• Tatiana V. Petrenko and
• Andrei I. Khlebnikov

Beilstein J. Org. Chem. 2011, 7, 1526–1532, doi:10.3762/bjoc.7.179

• been reported, and some of them were found to be effective inhibitors of steel corrosion [2], while their chromium(III) and palladium(II) complexes demonstrated catalytic activity in ethylene oligomerization [3] and Heck cross-coupling reactions [4]. Recently we and others have reported high superoxide

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• coworkers were able to open meso-epoxides asymmetrically with HF equivalents and chiral chromium–salen complexes [25][26]. In the year 2000, two conceptually different applications of Banks’ electrophilic fluorinating reagent F–TEDA (1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• -activated alkynes and a cycloheptatriene. These cycloadditions were previously reported in the context of a stoichiometric chromium(0) activation of the triene unit [64]. The use of AuCl3 or PtCl2 rendered the reaction catalytic [65]. The mechanism entails a stepwise exo-cyclization of the cycloheptatriene

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• benzobicyclo[5.3.1]acetals 87 were produced when triazole–gold was employed as the catalyst. With alcohol nucleophiles, gold(I)-catalyzed cyclization of o-alkynyl benzaldehyde 88 and benzaldimine–chromium complexes gave stereoselectively 1-anti-functionalized heterocycle chromium complexes 89 (Scheme 16) [47

• ]. This made the methodology useful for the synthesis of enantiomerically pure trans- and cis-1,3-dimethylisochromans starting from a single planar chiral chromium complex. 2.3 Carboxylates as nucleophiles Seraya has reported the gold-catalyzed rearrangement of cyclopropenylmethyl acetates as a route to

• nucleophiles to allenes, the addition of oxygen nucleophiles requires the use of chiral anions 384 (Scheme 62). Gold(I)-catalyzed asymmetric cyclization of 1,3-dihydroxymethyl-2-alkynylbenzene chromium complexes 389 gave planar chiral isochromene–chromium complexes 390 with high enantioselectivity [179

Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B

• Silke Dubberke,
• Muhammad Abbas and
• Bernhard Westermann

Beilstein J. Org. Chem. 2011, 7, 421–425, doi:10.3762/bjoc.7.54

• presence of a catalytic amount of hydroquinone. The resulting suspension was heated under reflux in an argon atmosphere for 7 h. At the end of the reaction, ethyl acetate (1 mL) was added and the product separated from the chromium salts by passage through a short column of silica gel (petroleum/ethyl

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• later Mori [22][23] utilized chromium alkoxycarbene to develop the first cyclizations via catalytic intramolecular enyne metathesis transformation. These initial works gave reason to postulate the interaction of metal carbene with alkyne to form a metallacyclobutene that rearranges to give a metal

Synthesis of Ru alkylidene complexes

• Renat Kadyrov and
• Anna Rosiak

Beilstein J. Org. Chem. 2011, 7, 104–110, doi:10.3762/bjoc.7.14

• ) [13] internal rotation barriers of styrene, 2-vinylthiophene (Ea = 4.8 kcal/mol) [14] and is comparable with rotation barrier of the aryl ring in chromium carbene complexes (ΔG≠298K = 13.0–16.2 kcal/mol) [15]. Experimental Routine, 2D-correlation spectra (1H,1H-COSY) and SELNOE experiments were

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• donor in specific organometallic reactions, such as the chromium-mediated allylation of aldehydes and ketones [54][55] and the palladium-catalyzed reductive homo-coupling of aryl halides to afford the corresponding biaryls [56][57][58][59] illustrate further versatility of the reagent. The fact that

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

• being reacted with each of molybdenum hexacarbonyl/DMSO[21]; tungsten pentacarbonyl/THF[22]; chromium hexacarbonyl and rhodium cycloooctadiene chloride dimer/pentafluorobenzaldehyde[23][24]. None of the promoters gave any Pauson-Khand adducts, although an interesting THF-insertion adduct was obtained

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

• allenylsilane product. We have not as yet examined the use of the more reactive Tebbe reagent which may function effectively at lower temperatures and hence offer a solution to this current limitation. Additionally, it will be of future interest to investigate the chromium-based Takai procedures for olefination